Musculoskeletal Neoplasms

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Ovid: Musculoskeletal Imaging Companion

Editors: Berquist, Thomas H.

Title: Musculoskeletal Imaging Companion, 2nd Edition

> Table of Contents > Chapter 10 – Musculoskeletal Neoplasms

Chapter 10

Musculoskeletal Neoplasms

Thomas H. Berquist

Mark J. Kransdorf

Bone Tumors/Tumorlike Conditions: Imaging Approaches

Key Facts

Imaging studies are essential for detecting, characterizing, and staging bone lesions.
Radiographs, computed tomography (CT),
magnetic resonance imaging (MRI), and radionuclide scans all play a
role. Angiography is useful for evaluating tumor vascularity and for
preoperative embolization.

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Effectiveness of imaging studies for evaluating features of bone tumors is as follows:

Radiographs	CT	MRI	Radionuclide Scans
Lesion morphology	Thin cortical bone	Lesion extent	Early detection in marrow and soft tissues
Site (cortical, marrow, diaphysis, metaphysis, epiphysis)	Bone destruction or production	Joint space involvement	Skip lesions
Bone production or destruction	Periosteal response	Marrow edema patterns	Metastasis
Periosteal response	Calcifications/matrix	Cortical destruction
Soft tissue calcification or ossifications	Trabecular destruction

Suggested Reading

Greenfield GB, Arrington JA. Imaging of bone tumors: A multimodality approach. Philadelphia: JB Lippincott; 1995.

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Bone Tumors/Tumorlike Conditions: Radiographic Features

Key Facts

Routine radiographs provide vital and
fundamental information regarding tumors and tumorlike conditions of
bone. Key features are as follows:

Patterns of bone destruction:
- Geographic: least aggressive. Margins may be sclerotic, well defined without sclerosis, or ill defined.
- Moth-eaten: more aggressive, less well defined. Longer zone of transition. Seen with malignant lesions and osteomyelitis.
- Permeative: most aggressive with more
  rapid destruction. Margins not defined. Seen with Ewing sarcoma,
  aggressive malignancies, and infections.
Bone formation
Matrix—calcification or ossification
Trabeculation—seen with giant cell tumors, chondromyxoid fibroma, aneurysmal bone cyst, hemangioma, nonossifying fibroma
Cortical penetration
Periosteal response
Soft tissue mass
Distribution:
- Central, eccentric, cortical, juxtacortical
- Diaphyseal, metaphyseal, epiphyseal
- Skeletal location (e.g., tibia and calcaneus)

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FIGURE 10-1 Patterns of bone destruction—geographic. (A) Lateral radiograph of the calcaneus showing a well-defined geographic lytic lesion (arrows). T1-weighted (B) and T2-weighted (C) magnetic resonance (MR) images showing homogeneous fluid signal caused by a benign unicameral bone cyst.

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FIGURE 10-2
Moth-eaten. Lateral view of the femur showing a destructive lesion with
poorly defined margins and a pathologic fracture anteriorly (arrowhead) as the result of metastasis.

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FIGURE 10-3 Permeative. Poorly defined lytic lesion in the proximal humerus with permeative cortical changes attributable to Ewing sarcoma.

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FIGURE 10-4
Matrix calcifications. Axial CT image of the distal tibial epiphysis
showing a well-defined geographic lesion with calcifications.
Appearance and location characteristic of chondroblastoma.

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FIGURE 10-5 Periosteal response. Osteogenic sarcoma with bone sclerosis and cortical break: a triangular elevation (arrow) (Codman triangle) seen with aggressive lesions.

Suggested Reading

Greenspan A, Remagen W. Differential diagnosis of tumors and tumorlike lesion of bone and joints. Philadelphia: Lippincott-Raven; 1998:1–24.

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Bone Tumors/Tumorlike Conditions: Magnetic Resonance Imaging Protocols

Key Facts

MRI of bone tumors is approached somewhat differently compared with other indications.
The field of view needs to include a larger area to evaluate adjacent joints and to avoid overlooking skip lesions.
Image planes, especially for long bones, should be selected to demonstrate the osseous structure on one image.
Coil selected should be large enough to cover the needed anatomic area.
Pulse sequences typically include axial
T1- and T2-weighted spin-echo MR images. We prefer conventional T2
images to turbo T2 or fat-suppressed turbo T2 images.
Contrast enhancement is used routinely.

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FIGURE 10-6
Patient with a knee sarcoma and midfemoral skip lesion. The knee coil
would be optimal for knee imaging, but the skip lesion would not be
identified unless the larger body coil was used to evaluate the entire
femur.

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FIGURE 10-7 Optimal image planes. (A,B)
Sarcoma in the proximal femur with level of excision for limb salvage
marked on coronal images. At least 5 to 7 cm of normal marrow usually
is included in the resection. (C) Optimal sagittal image in a different patient showing the entire area of interest on one image. Line marks planned resection.

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Suggested Reading

Kransdorf MJ, Berquist TH. Musculoskeletal neoplasms. In: Berquist TH, ed. MRI of the musculoskeletal system, 5th ed. Philadelphia: Lippincott Williams & Wilkins; 2006:802–915.

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Bone Tumors/Tumorlike Conditions: Osteoid Osteoma

Key Facts

Clinical:
- Osteoid osteoma is a relatively common
  lesion accounting for 12% of benign bone tumors. Patients present with
  pain, worse at night, often relieved by anti-inflammatory medications
  (75%).
Age: 5 to 35 years, peak second decade
Sex: Males outnumber females 3:1.
Common locations: majority in lower extremity; proximal femur, femoral neck
Three types of osteoid osteoma:
- Cortical: most common. Fusiform cortical thickening with a lucent nidus. May contain central calcification.
- Cancellous: femoral neck and small bones of the hand, foot, and posterior elements of the spine.
- Subperiosteal: least common. Arise in soft tissue adjacent to bone.
Imaging features:
- Radiographic features: small round lucent
  area, usually in cortex with surrounding sclerosis. May have central
  calcification or ossification.
- CT: technique of choice for detection and characterization.
- MRI: small focal lesion with bone and
  soft tissue edema on T2-weighted or short T1 inversion recovery (STIR)
  images. Subtle lesions enhance with dynamic contrast studies.
Differential diagnosis:
- Brodie abscess
- Osteoblastoma
- Stress fracture
Treatment: complete resection of nidus; percutaneous radiofrequency ablation.

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FIGURE 10-8 Intracapsular osteoid osteoma. Coronal T1-weighted (A) and fluid-sensitive (B) weighted images showing a large area of signal abnormality in the right femoral neck. (C) Axial T2-weighted image shows fluid in the joint with a small high signal intensity nidus (arrowhead) and surrounding edema. (D) Axial CT image demonstrates the lucent nidus (arrowhead) more clearly.

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FIGURE 10-9 Tibial osteoid osteoma. (A) Posterior image from a bone scan showing increased tracer in the medial tibia. (B) CT scan clearly defines the nidus (arrow) and surrounding bone sclerosis.

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Suggested Reading

Assorin J, Richardi G, Railhec JJ, et al. Osteoid osteoma. MR imaging versus CT. Radiology 1994;191:217–233.

Greenspan A. Benign bone forming lesions: Osteoma, osteoid osteoma, osteoblastoma. Skel Radiol 1993;22:485–500.

Liu PT, Chivers FS, Roberts CC, et al. Imaging of osteoid osteoma by dynamic gadolinium-enhanced imaging. Radiology 2003;277:691–700.

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Bone Tumors/Tumorlike Conditions: Osteoblastoma

Key Facts

Clinical:
- Osteoblastomas account for 3.5% of benign bone tumors. Patients present with chronic local pain.
Age: any age, most common second decade
Sex: Males outnumber females 3:1.
Common locations: vertebrae (42.5%), posterior elements most commonly involved
Imaging features:
- Radiographic features: May be similar to
  osteoid osteoma, but larger (>1.5 cm). May have malignant
  appearance. Bone expanded; 55% have an ossified matrix.
- CT: cortical expansion, ossified matrix
- MRI: variable, not well defined
Differential diagnosis:
- Osteoid osteoma
- Aneurysmal bone cyst
- Osteosarcoma
Treatment: en bloc resection, bone grafting

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FIGURE 10-10 Osteoblastoma. Sagittal (A) and axial (B)
contrast-enhanced T1-weighted images showing a large enhancing lesion
that appears to involve the body and neural arch with spinal cord
compression. Axial (C), sagittal (D), and coronal (E) CT images demonstrate matrix calcification or ossification with a thin cortical rim characteristic of osteoblastoma.

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Suggested Reading

McLeod RA, Dahlin DC, Beabout JW. The spectrum of osteoblastoma. AJR Am J Roentgenol 1976;126:321–335.

Unni KK. Dahlin’s bone tumors: General aspects and data on 11,087 cases. Philadelphia: Lippincott-Raven; 1996:131–142.

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Bone Tumors/Tumorlike Conditions: Osteochondroma

Key Facts

Clinical:
- Osteochondromas are the most common
  accounting for 35% of benign skeletal neoplasms. Patients present with
  a palpable mass that may be painful.
Age: 5 to 50 years, peak second decade
Sex: Males outnumber females 2:1.
Common locations: distal femur, proximal tibia, proximal humerus
Imaging features:
- Radiographic features: bony projection with contiguous marrow and cortex from bone of origin
- CT: similar to radiograph. Cartilaginous cap more easily appreciated (normal cap thickness <1.5–2 cm).
- MRI: cartilage cap low intensity on
  T1-weighted and high intensity on T2-weighted sequences. Other features
  similar to radiographs.
Differential diagnosis:
- Usually characteristic
- Myositis ossificans
Treatment: Observe unless symptoms or cosmetic deformity, then resect.

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FIGURE 10-11 Anteroposterior (AP) (A) and lateral (B) radiographs of an osteochondroma. Coronal T1-weighted (C) and axial T2-weighted (D) images showing marrow extending into the lesion (arrow) and a thin high signal intensity cartilaginous cap (arrowheads).

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FIGURE 10-12 Axial CT of an osteochondroma arising from the upper tibia.

Suggested Reading

Unni KK. Dahlin’s bone tumors: General aspects and data on 11,087 cases, 5th ed. Philadelphia: Lippincott-Raven; 1996:11–24, 121–130, 355–432.

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Bone Tumors/Tumorlike Conditions: Enchondroma

Key Facts

Clinical:
- Enchondromas account for 13.4% of benign
  bone tumors. Most are asymptomatic. If painful, low-grade
  chondrosarcoma should be excluded. Chondrosarcomas have more intense
  uptake on radionuclide scans and typically erode two thirds of the
  cortical thickness. There may also be periosteal reaction and a soft
  tissue mass.
Age: all age groups, 55% in the second through fourth decades
Sex: no sex predilection
Common locations: small bones of hand and feet (50%) with 87% in the hand, proximal femur, and humerus
Imaging features:
- Radiographic features: medullary with sharp margins. Calcification common. May be multiple.
- CT: well-defined lesion with central calcified matrix. Cortical erosion easily measured.
- MRI: lobulated low intensity on
  T1-weighted and high intensity on T2-weighted images. Useful for
  differentiating enchondroma from chondrosarcoma. Mineralized areas show
  decreased signal intensity on all pulse sequences.
Differential diagnosis:
- Bone infarct
- Chondrosarcoma
Treatment: Observe. Curettage and bone graft if symptomatic.

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FIGURE 10-13 AP (A) and lateral (B) radiographs of a phalangeal enchondroma. There is cortical expansion and a pathologic fracture (arrow).

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FIGURE 10-14 Enchondroma in a 52-year-old woman. (A)
Routine radiograph of the shoulder showing a focus of calcifications in
the marrow of the humeral neck with no endosteal scalloping. Coronal
T1-weighted (B) and T2-weighted (C)
MR images showing areas of low and high intensity in the enchondroma as
the result of calcifications. There is no marrow edema, cortical
destruction, or soft tissue mass.

Suggested Reading

Murphy MD, Flemming DJ, Boyea SR, et al. Enchondroma vs. chondrosarcoma in the appendicular skeleton: Differentiating features. Radiographics 1998;18:1213–1237.

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Bone Tumors/Tumorlike Conditions: Chondroblastoma

Key Facts

Clinical:
- Patients present with chronic local pain.
Age: 90% occur from 5 to 25 years of age, approximately 70% in second decade.
Sex: Males outnumber females 2–3:1.
Common locations: epiphyseal with 40% in the knee and 16% in the proximal humerus
Imaging features:
- Radiographic features: epiphyseal location. Sharp margins with sclerotic rim. Calcification in approximately 50% to 60%.
- CT: well-defined lesion with sclerotic margins and, frequently, central calcification
- MRI: well-defined low-intensity lesion on
  T1-weighted and variably high signal intensity on T2-weighted
  sequences, with extensive surrounding edema in the majority of cases
Differential diagnosis:
- Giant cell tumor
- Avascular necrosis
- Clear cell chondrosarcoma
Treatment: curettage and bone grafting

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FIGURE 10-15 Chondroblastoma. (A)
AP radiograph demonstrates a proximal tibial lesion with sclerotic
margins and calcifications. There is subtle periosteal reaction (arrow). Coronal T1- (B) and T2-weighted (C) images demonstrate a well-defined lesion with marrow edema pattern.

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Suggested Reading

Unni KK. Dahlin’s bone tumors: General aspects and data on 11,087 cases. Philadelphia: Lippincott-Raven; 1996:47–57.

Weatherall PT, Moole GE, Mendelsohn DB, et al. Chondroblastoma: Classic and confusing appearance at MR. Radiology 1994;190:467–474.

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Bone Tumors/Tumorlike Conditions: Chondromyxoid Fibroma

Key Facts

Clinical:
- Patients present with local pain and swelling.
Age: 5 to 50 years, most common (55%) in the second and third decades
Sex: slightly more common in males
Common locations: metaphysis of the knee and distal tibia
Imaging features:
- Radiographic features: eccentric
  metaphyseal lesion with well-defined sclerotic margins. Calcifications
  seen in 12%, more common in those aged more than 40 years.
- CT: eccentric metaphyseal lesion with well-defined sclerotic margins. Calcifications easily appreciated
- MRI: well-defined lesion with uniform low intensity on T1-weighted and high or intermediate intensity on T2-weighted sequences
Differential diagnosis:
- Fibrous defect
- Fibrous dysplasia
- Chondroblastoma
- Aneurysmal bone cyst
Treatment: curettage and bone grafting

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FIGURE 10-16 Chondromyxoid fibroma in a 45-year-old woman. (A) Oblique radiograph of the knee showing a lytic lesion with sclerotic margins (arrows). (B) Axial CT showing the well-defined sclerotic margins with no matrix calcifications. Axial T1-weighted (C), axial enhanced T1-weighted (D), and T2-weighted coronal (E) images showing the lesion to be low signal intensity on T1 (D) with peripheral enhancement.

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Suggested Reading

Rahimi A, Beabout JW, Ivens JC, et al. Chondromyxoid fibroma: A clinicopathological study of 76 cases. Cancer 1972;30:726–736.

Yamaguchi T, Dorfman HD. Radiographic and histologic patterns of calcification in chondromyxoid fibroma. Skel Radiol 1998;27:559–564.

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Bone Tumors/Tumorlike Conditions: Nonossifying Fibroma

Key Facts

Clinical:
- Nonossifying fibroma, fibrous cortical
  defect, and fibroxanthoma describe similar metaphyseal lesions. Lesions
  are common and typically discovered incidentally.
Age: 5 to 35 years, peak second decade
Sex: No sex predilection.
Common locations: distal femur, distal tibia
Imaging features:
- Radiographic features: well-defined eccentric lytic defect with scalloped sclerotic margins in the metaphysis of a long bone
- CT: well-defined eccentric lytic defect with scalloped sclerotic margins in the metaphysis of a long bone
- MRI: well-defined cortical lesion with
  low to intermediate intensity on T1-weighted and low to intermediate
  signal intensity on T2-weighted sequences
Differential diagnosis:
- Fibrous dysplasia
- Chondromyxoid fibroma
- Eosinophilic granuloma
Treatment: none unless potential for pathologic fracture

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FIGURE 10-17 Nonossifying fibromas in the tibia and femur of a 15-year-old boy. AP (A) and lateral (B) radiographs showing lucent lesions in the tibia and femur (arrowheads) with well-defined sclerotic margins. There also is osteochondritis dissecans in the medial femoral condyle. (C,D) Sagittal T2-weighted MR images showing high signal intensity with low intensity at the margin of the lesions.

Suggested Reading

Jee W, Choe B, Kang H, et al. Nonossifying fibroma. Characteristics at MR imaging with pathologic correlation. Radiology 1998;209:197–202.

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Bone Tumors/Tumorlike Conditions: Bone Cyst

Key Facts

Clinical:
- Patients are asymptomatic unless pathologic fracture occurs.
Age: first two decades
Sex: Males outnumber females 3:1.
Common locations: proximal humerus, femur, or tibia (90% in humerus or femur)
Imaging features:
- Radiographic features: well-defined lytic
  lesion frequently near the physis. May be septated. If fracture has
  occurred, the “fallen fragment sign” (bone fragment in the dependent
  portion of the cyst) is virtually pathognomonic.
- CT: fluid density, well-defined lesion with bony septations
- MRI: uniformly low intensity on
  T1-weighted and high intensity on T2-weighted sequences. Fluid–fluid
  level or “fallen fragment” after fracture.
Differential diagnosis:
- Aneurysmal bone cyst
- Fibrous dysplasia
Treatment: aspiration and steroid injection. If in a weight-bearing region, consider curettage and bone grafting.

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FIGURE 10-18 Unicameral bone cyst. AP radiograph of the humerus with a bone cyst and pathologic fracture with the “fallen fragment sign” (arrows).

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FIGURE 10-19 Unicameral bone cyst. Sagittal T1-weighted (A) and STIR (5300/30/150) (B) images showing low intensity on T1-weighted (A) and high intensity on STIR (B) consistent with a fluid-filled cyst.

Suggested Reading

Conway WF, Hayes CW. Miscellaneous lesions of the bone. Radiol Clin North Am 1993;31:299–323.

Kileen K. The fallen fragment sign. Radiology 1998;207:261–262.

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Bone Tumors/Tumorlike Conditions: Aneurysmal Bone Cyst

Key Facts

Clinical:
- Patients present with pain.
Age: 5 to 35 years, 80% in the first two decades
Sex: Females slightly outnumber males.
Common locations: more than 50% in the long bones; 12% to 30% in the spine
Imaging features:
- Radiographic features: eccentric lytic
  lesion with expanded or “ballooned” bony contour. Sclerotic rim and
  periosteal response are common.
- CT: same features as radiographs but fluid density
- MRI: well-defined lesion with high signal intensity on T2-weighted sequences. Fluid–fluid levels are common.
Differential diagnosis:
- Bone cyst
- Giant cell tumor
- Osteoblastoma (vertebral location)
Treatment: curettage and bone grafting

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FIGURE 10-20 Aneurysmal bone cyst. (A) AP radiograph showing a lytic expanding lesion in the upper tibia. Coronal T1-weighted (B) and axial T2-weighted (C) MR images showing a cystic lesion with fluid–fluid levels.

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Suggested Reading

Munk PL, Helms CA, Holt RG, et al. MR imaging of aneurysmal bone cysts. AJR Am J Roentgenol 1989;153:99–101.

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Bone Tumors/Tumorlike Conditions: Fibrous Dysplasia

Key Facts

Clinical:
- Typically asymptomatic. Abnormal bone
  growth may cause deformity. Lesions may be single (monostotic) in which
  case the femur, tibia, ribs, and skull base are most commonly involved.
  Multiple lesions (polyostotic) involve one side of the skeleton in 90%
  of patients. These lesions are more often symptomatic and may enlarge
  until skeletal maturity.
Associated syndromes:
- Mazabraud syndrome: fibrous dysplasia and multiple intramuscular myxomas
- Albright-McCune: females with polyostotic dysplasia, skin lesions, and precocious puberty
Age: most often second or third decade
Sex: slightly more common in females
Common locations: skull, mandible, ribs, femoral neck, tibia
Imaging features:
- Radiographic features: metaphyseal or
  diaphyseal lytic or “ground glass” density with sharp margins and bone
  expansion. May affect multiple bones in approximately 15% of patients.
  “Long lesion in long bone.”
- CT: well-defined lesion with sclerotic margins
- MRI: well-defined lesion with
  low-intensity margins. Low signal intensity on T1-weighted and
  intermediate signal intensity on T2-weighted sequences.
Differential diagnosis:
- Nonossifying fibroma
- Bone cyst
- Aneurysmal bone cyst
- Chondromyxoid fibroma
Treatment: observation

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FIGURE 10-21 Thirteen year old male with polyostotic fibrous dysplasia. (A) AP radograph of the pelvis demonstrates lucent lesions in the ilium and femur. (B) Radionuclide bone scan shows multiple lesions on the left involving the pelvis, femur, and tibia. Coronal T1- (C) and T2-weighted (D) images demonstrate abnormal signal intensity in the involved bones with expansion of the femoral neck.

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Suggested Reading

Campanacci M, Laus M. Osteofibrous dysplasia of the tibia and fibula. J Bone Joint Surg 1981;63A:367–375.

Gober
GA, Nicholas RW. Case report 800. Skeletal fibrous dysplasia associated
with intramuscular myxomas (Mazabraud’s syndrome). Skel Radiol 1993;22:452–455.

Greenspan A, Remagen W. Differential diagnosis of tumors and tumorlike lesions in bone and joints. Philadelphia: Lippincott-Raven; 1998:215–223.

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Bone Tumors/Tumorlike Conditions: Giant Cell Tumor

Key Facts

Clinical:
- Giant cell tumors account for 22.7% of
  benign bone tumors. Patients present with pain and swelling in the
  involved site. A tender palpable mass commonly present.
Age: 20 to 40 years
Sex: Females affected slightly more frequently than males.
Common locations: most involve the distal
femur or proximal tibia (46%) followed by the distal radius and sacrum.
Epiphyseal location.
Imaging features:
- Radiographic features: lytic lesion with
  nonsclerotic margins originating in the metaphysis but extending to
  subchondral bone. Cortical breakthrough in 33% to 50% of cases.
- CT: similar to radiographs. No tumor matrix.
- MRI: low intensity on T1-weighted and
  intermediate signal on T2-weighted sequences. T2 sequences may show
  decreased signal because of hemosiderin deposition. In some cases,
  signal intensity increased on T2-weighted images. May have fluid–fluid
  levels. Enhanced on post-contrast images.
Differential diagnosis:
- Chondroblastoma
- Osteosarcoma
- Fibrosarcoma
- Malignant fibrous histiocytoma
Treatment: resection with grafting or, in some cases, joint prosthesis

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FIGURE 10-22 Giant cell tumor. (A) AP radiograph demonstrates a poorly defined lesion involving the epiphysis and metaphysis. Coronal T1- (B) and postcontrast T1-weighted (C) images show low signal intensity on the T1-weighted image (B) and contrast enhancement (C). Coronal (D) and axial (E) CT images showing low attenuation with no calcified matrix.

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Suggested Reading

Aoki
J, Tanikawa H, Ishü K, et al. MR findings indicative of hemosiderin in
giant-cell tumor of bone: Frequency, cause, and diagnostic
significance. AJR Am J Roentgenol 1996;166:145–148.

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Bone Tumors/Tumorlike Conditions: Eosinophilic Granuloma

Key Facts

Clinical:
- Patients present with pain. Multisystem disease is associated with Hand-Schüller-Christian or Letterer-Siwe variants.
Age: 1 to 20 years
Sex: Males outnumber females 2:1.
Common locations: Skull most common; any bone may be involved.
Imaging features:
- Radiographic features: variable, but
  lesions usually lytic with variable margins. May be multiple (one
  third). Medullary expansion, periosteal response, and sclerosis in long
  bones. Epiphysis usually involved. Lesions may have double contour
  margins.
- CT: similar to radiographic features. Cortical and periosteal changes more easily appreciated.
- MRI: well-defined lesions with
  intermediate or high signal intensity on T1- and T2-weighted images
  (increased signal on T1 because of xanthomatous histiocytes).
Differential diagnosis:
- Osteomyelitis
- Malignancy
- Metastasis
Treatment: resection and bone grafting for solitary lesion. Patients with multiple lesions observed as lesions may regress.

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FIGURE 10-23 Eosinophilic granuloma. (A) Radiograph showing a lytic lesion with endosteal scalloping (open arrows) and solid laminated periosteal new bone. Coronal T1-weighted (B) and T2-weighted (C) images showing a focal area of low intensity on T1-weighted (B) and high intensity on T2-weighted (C) images. There is associated marrow edema. Periosteal new bone is low intensity on both sequences.

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Suggested Reading

DeSchepper AMA, Ramon F, Van Marck E. MR imaging of eosinophilic granuloma in bone. A report of 11 cases. Skel Radiol 1993;22:163–166.

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Bone Tumors/Tumorlike Conditions: Osteosarcoma

Key Facts

Clinical:
- Osteosarcomas account for 19% of sarcomas
  and except for myeloma are the most common primary bone malignancy.
  Patients present with pain and swelling in the affected region.
Age: Second decade is the peak incidence.
Sex: Males slightly outnumber females.
Common locations: distal femur or proximal tibia (48%), pelvis and proximal femur (14%), shoulder and proximal humerus (10%)
Imaging features:
- Radiographic features: metaphyseal lytic,
  blastic, or mixed appearance. Lesions poorly defined with aggressive
  periosteal response (spiculations or Codman triangles). Soft tissue
  extension common.
- CT: similar to radiographic features
- MRI: Imaging features are nonspecific.
  Signal intensity varies with matrix (decreased with blastic, increased
  with lytic on T2-weighted sequence). Staging of marrow and soft tissue
  involvement is the primary indication for MRI.
Differential diagnosis:
- Ewing sarcoma
- Fibrosarcoma
- Chondrosarcoma
- Giant cell tumor
- Osteomyelitis
Treatment: limb salvage or amputation. Radiation and chemotherapy as adjuvant therapy or for nonoperable lesions.

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FIGURE 10-24 Osteogenic sarcoma. (A) Fourteen-year-old female with a sclerotic osteosarcoma and Codman triangle (arrow) medially. AP (B) and lateral (C) radiographs of a lytic osteosarcoma with early periosteal reaction in a different patient.

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FIGURE 10-25 Coronal (A) and axial (B) T2-weighted images of a tibial osteosarcoma invading the joint space (arrow) and with a significant soft tissue mass.

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Suggested Reading

Azouz ME, Esseltine DW, Chevalier L. Radiographic evaluation of osteosarcoma. J Can Assoc Radiol 1982;33:167–171.

Unni KK. Dahlin’s bone tumors: General aspects and data on 1,087 cases. Philadelphia: Lippincott-Raven; 1996:143–183.

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Bone Tumors/Tumorlike Conditions: Parosteal Osteosarcoma

Key Facts

Clinical:
- Patients typically present with a painless mass in the distal posterior thigh.
Age: Third decade (older than conventional osteosarcoma)
Sex: Females outnumber males 2:1.
Common locations: majority in distal posterior femur (67%), proximal tibia or fibula (12%), proximal humerus (10%)
Imaging features:
- Radiographic features: large ossified
  mass on the surface of a long bone. Cortex thick and deformed. Larger
  masses may surround bone.
- CT: similar to radiographs. Lucent zone (periosteum) separates the tumor from the cortex (string sign).
- MRI: often not required because of characteristic CT features and lack of improved specificity for MRI.
Differential diagnosis:
- Myositis ossificans
- Periosteal osteosarcoma
- Osteosarcoma
- Periosteal chondrosarcoma
Treatment: limb salvage resection

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FIGURE 10-26 Parosteal osteogenic sarcoma. AP (A) and lateral (B) radiographs showing dense osseous mass surrounding the lower femur. (C) CT image showing the dense osseous mass around the femur.

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Suggested Reading

Greenfield GB, Arrington JA. Imaging of bone tumors: A multimodality approach. Philadelphia: JB Lippincott; 1995:43–166.

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Bone Tumors/Tumorlike Conditions: Periosteal Osteosarcoma

Key Facts

Clinical:
- Periosteal osteosarcomas account for only 1.5% of osteosarcomas. Patients present with local pain over involved bone.
Age: 15 to 30 years, peak in the second decade
Sex: Females outnumber males 1.6:1.
Common locations: diaphysis of femur and tibia (73%)
Imaging features:
- Radiographic features: surface lesion on the diaphysis with partial calcification or ossification. Medullary bone not involved.
- CT: similar to radiographic features. Confirms marrow sparing.
- MRI: normal marrow with variable signal intensity in periosteum and soft tissues, depending on calcifications
Differential diagnosis:
- Myositis ossificans
- Parosteal osteosarcoma
- Periosteal chondrosarcoma
Treatment: wide excision and bone graft (allograft)

FIGURE 10-27 Periosteal osteosarcoma. AP (A) and lateral (B) radiographs showing a large mineralized soft tissue mass without obvious bone destruction.

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Suggested Reading

Unni KK, Dahlin DC, Beabout JW. Periosteal osteogenic sarcoma. Cancer 1976;37:2476–2485.

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Bone Tumors/Tumorlike Conditions: Telangiectatic Osteosarcoma

Key Facts

Clinical:
- Telangiectatic osteosarcomas account for 3.5% of all osteosarcomas. Patients present with pain.
Age: 15 to 35 years, peak incidence in the second decade
Sex: Males outnumber females 2:1.
Common locations: distal femur and proximal tibia (61%), humerus (14%)
Imaging features:
- Radiographic features: large lytic or
  permeative metaphyseal lesion. Cortical destruction with aggressive
  periosteal response and soft tissue mass.
- CT: similar to radiographic features
- MRI: high-intensity bone and soft tissue
  lesion on T2-weighted images; low-intensity on T1-weighted images.
  Signal intensity may be mixed, especially on T1-weighted images because
  of clotted blood. Fluid–fluid levels.
Differential diagnosis:
- Osteosarcoma
- Fibrosarcoma
- Aneurysmal bone cyst
Treatment: limb salvage with wide excision

FIGURE 10-28
Telangiectatic osteosarcoma. AP radiograph demonstrating a permeative
lytic lesion in the proximal tibia with pathologic fracture medially (arrow).

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FIGURE 10-29 Telangiectatic osteosarcoma. AP (A) and lateral (B) radiographs showing a permeative lesion with aggressive periosteal reaction. Coronal T2-weighted (C) and axial T1-weighted (D) MR images showing a large soft tissue mass with multiple fluid intensity collections on T2-weighted image (C).

Suggested Reading

Huvos AG, Rosen G, Bretsky SS, et al. Telangiectatic osteosarcoma: A clinicopathologic study of 124 cases. Cancer 1982;49:1679–1689.

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Bone Tumors/Tumorlike Conditions: Ewing Sarcoma

Key Facts

Clinical:
- Ewing sarcomas account for 9.1% of all
  primary malignant bone tumors. Patients present with local pain and
  swelling. Patients may also have fever and increased white counts
  suggesting infection.
Age: 5 to 30 years, 75% in the first two decades and 60% in the second decade
Sex: no sex predilection
Common locations: pelvis and sacrum (25%), femur and tibia (27%), humerus and forearm (12%), foot and ankle (8%)
Imaging features:
- Radiographic features: long diaphyseal
  lesion with permeative pattern. May have sclerosis or mixed appearance.
  Aggressive periosteal (laminated characteristic of Ewing sarcoma)
  response and soft tissue mass common.
- CT: similar to radiographic features; periosteum and soft tissue better defined.
- MRI: signal intensity variable in mixed
  or sclerotic lesions. High signal intensity on T2-weighted and low
  signal intensity on T1-weighted with lytic permeative lesions.
Differential diagnosis:
- Lymphoma
- Osteosarcoma
- Osteomyelitis
Treatment: radiation or radiation plus chemotherapy. Surgical therapy is more often considered recently.

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FIGURE 10-30 Ewing sarcoma. AP radiograph of the femur demonstrating a long lytic lesion with laminated periosteal reaction.

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FIGURE 10-31 Ewing sarcoma. AP radiograph (A) showing a lytic lesion in the distal fibular diaphysis and metaphysis. T2-weighted sagittal (B) and axial (C) images showing a high signal intensity medullary lesion with soft tissue involvement.

Suggested Reading

Fletcher BD. Responses of osteosarcoma and Ewing’s sarcoma to chemotherapy. Imaging evaluation. AJR Am J Roentgenol 1991;157:825–833.

Unni KK. Dahlin’s bone tumors: General aspects and data on 11,087 cases. Philadelphia: Lippincott-Raven; 1996:249–261.

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Bone Tumors/Tumorlike Conditions: Chondrosarcoma (Primary, Central)

Key Facts

Clinical:
- Chondrosarcomas account for 9.2% of
  malignant bone tumors. Osteosarcomas are twice as common. A
  chondrosarcoma originating in bone is considered central. Patients
  present with pain.
Age: more common in adults 40 to 60 years old (62%)
Sex: Males outnumber females 1.5:1.
Common locations: pelvic region most
common (23%), proximal femur (13.5%), proximal humerus (12%), trunk
(10.6%), proximal tibia and fibula (7%)
Imaging features:
- Radiographic features: Two thirds are
  calcified. Cortical erosion or destruction usually is present.
  Typically, little periosteal response. Soft tissue extension common
  with large lesions.
- CT: superior for evaluation of cortex and matrix calcification
- MRI: intermediate to high intensity on
  T2-weighted sequences. Calcification seen as low intensity on T1- and
  T2-weighted sequences. Soft tissue extension more easily evaluated
  compared with CT.
Differential diagnosis:
- Osteosarcoma
- Fibrosarcoma
- Metastasis
Treatment: wide excision with reconstruction

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FIGURE 10-32 Central chondrosarcoma. (A) Radiograph of the humerus showing a chondroid lesion with calcifications and endosteal scalloping (arrows). Sagittal T1-weighted (B) and axial T2-weighted (C) images showing cortical destruction with soft tissue mass (arrows) indicating a malignant lesion.

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Suggested Reading

Hudson TM, Manaster BJ, Springfield DS, et al. Radiology of medullary chondrosarcoma: Preoperative treatment planning. Skel Radiol 1983;10:69–78.

Murphey
MD, Flemming DJ, Boyea SR, et al. Enchondroma versus chondrosarcoma in
the appendicular skeleton: Differentiating features. Radiographics 1998;18:1213–1237.

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Bone Tumors/Tumorlike Conditions: Chondrosarcoma (Secondary)

Key Facts

Clinical:
- Secondary chondrosarcomas originate from
  osteochondromas or enchondromas. Patients with enchondromas present
  with pain. Patients with osteochondromas present with enlarging masses
  and pain. Malignant changes are more common in patients with multiple
  osteochondromas.
Age: 30 to 50 years
Sex: Males outnumber females 2:1.
Common locations: shoulder and proximal humerus (10.4%), pelvis and proximal femur (33%), spine (10.4%)
Imaging features:
- Radiographic features: Irregular
  cartilage cap with streaky calcific densities and lucent areas in an
  osteochondroma suggest malignant transformation. With enchondromas,
  endosteal scalloping, disappearing calcifications, and increasing area
  of lucency suggest malignancy.
- CT: similar to radiographs but more useful for evaluating matrix, cartilage cap, and cortical involvement
- MRI: Lesions have increased intensity on
  T2-weighted and decreased intensity on T1-weighted sequences. Cartilage
  cap is easily defined (high signal intensity) and measured greater than
  1.5 to 2 cm suggests malignancy. Gadolinium-enhanced T1-weighted images
  show ring and arc septal pattern of chondrosarcoma.
Treatment: surgical resection with wide margins

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FIGURE 10-33 Secondary chondrosarcoma. (A) AP radiograph of the pelvis showing an osteochondroma with fragmentation in the region of the cartilaginous cap (arrows). (B) CT image taken during biopsy confirms the thick cap (lines) with scattered osseous densities. Coronal T1-weighted (C) and axial T2-weighted (D) MR images showing the thick irregular cartilaginous cap, which is high signal intensity on the T2-weighted image (D) and low signal intensity on T1-weighted image (C).

Suggested Reading

Aoki JA, Sone S, Fujioka F, et al. MR of enchondroma and chondrosarcoma. Rings and arcs of Gd-DTPA enhancement. J Comput Assist Tomogr 1991;15:1011–1016.

Unni KK. Dahlin’s bone tumors: General aspects and data on 11,087 cases. Philadelphia: Lippincott-Raven; 1996:71–108.

P.694

Bone Tumors/Tumorlike Conditions: Fibrosarcoma and Malignant Fibrous Histiocytoma

Key Facts

Clinical:
- These are uncommon malignancies of bone
  (1% of malignant bone tumors). Up to 30% arise from lesions such as
  radiation, bone infarcts, Paget disease, or chronic osteomyelitis.
  Patients present with pain and swelling.
Age: peaks in those aged in their 40s and 60s
Sex: no sex predilection
Common locations: distal femur and proximal tibia (35%), pelvis and proximal femur (27%), shoulder and humerus (10%)
Imaging features:
- Radiographic features: large,
  eccentrically located lytic lesion with poorly defined margins.
  Cortical disruption and soft tissue mass common.
- CT: similar to radiographic features
- MRI: high signal intensity on T2-weighted
  and typically low on T1-weighted sequences. Areas of hemorrhage may be
  high intensity on T1-weighted sequences. Marrow extent and soft tissue
  extension optimally imaged.
Differential diagnosis:
- Osteosarcoma
- Giant cell tumor
- Metastasis
Treatment: limb salvage with joint reconstruction

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FIGURE 10-34 Malignant fibrous histiocytoma. Routine radiographs showing a lytic lesion in the left ileum (A) that 11 months later (B) has increased dramatically and fractured laterally. (C,D) Axial CT images showing bone destruction and large soft tissue mass with osseous sequestra.

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Suggested Reading

Taconia WK, Mulder JD. Fibrosarcoma and malignant fibrous histiocytoma of long bones. Radiographic features and grading. Skel Radiol 1984;11:237–245.

Unni KK. Dahlin’s bone tumors: General aspects and data on 11,087 cases. Philadelphia: Lippincott-Raven; 1996:217–224.

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Bone Tumors/Tumorlike Conditions: Adamantinoma

Key Facts

Clinical:
- Adamantinomas account for less than 1% of all malignant bone tumors. Patients present with local pain.
Age: 74% in the second and third decades
Sex: no sex predilection
Common locations: tibial diaphysis (90%)
Imaging features:
- Radiographic features: eccentric lytic
  areas with sclerosis. Bone expanded. Typically dominant central lesion.
  May be multiple. Both the tibia and fibula may be involved.
- CT: defines cortical and soft tissue involvement
- MRI: features variable and not well documented
Differential diagnosis:
- Fibrous dysplasia
- Fibroma
Treatment: excision with wide margins

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FIGURE 10-35 Adamantinoma in a 21-year-old man. (A) Radiograph showing a lytic expanding lesion with cortical involvement in the midtibia. Sagittal T1-weighted (B) and axial T2-weighted (C) images showing a muscle intensity lesion on T1-weighted (B) and high-intensity lesion on T2-weighted (C) MR images.

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Suggested Reading

Levine SM, Lambiase RE, Petchprapa CN. Cortical lesions of the tibia: Characteristic appearances on radiography. Radiographics 2003;23:157–177.

Weiss
SW, Dorfman HD. Adamantinoma of long bones: An analysis of nine cases
with emphasis on metastasizing lesions and fibrous dysplasia-like
changes. Hum Pathol 1977;8:141–153.

P.700

Bone Tumors/Tumorlike Conditions: Paget Sarcoma

Key Facts

Clinical:
- Malignant degeneration occurs in 1% to 6%
  of patients with Paget disease. Most (50%) are osteosarcomas, followed
  by fibrosarcoma, chondrosarcoma, and other histologic types. Patients
  present with increasing or new pain in the region of Paget involvement.
Age: elderly
Sex: Males outnumber females 2:1.
Common locations: pelvis, proximal humerus
Imaging features:
- Radiographic features: Most lesions are
  lytic, but mixed lytic and sclerotic occur. Soft tissue involvement
  common. Originate in bone affected by Paget disease.
- CT: cortical destruction and soft tissue involvement more clearly defined
- MRI: variable signal intensity. Soft
  tissue extension easily identified. Low signal intensity on T1-weighted
  images in areas of lucency on the radiograph suggests malignant
  degeneration.
Treatment: wide excision or amputation. Radiation for nonsurgical cases.

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FIGURE 10-36 Paget sarcoma (osteosarcoma) in a 62-year-old man. (A) Radiograph showing changes of Paget disease with a lytic area and cortical destruction laterally (arrow). Coronal T1-weighted (B) and T2-weighted (C) MR images clearly define the bone destruction and large soft tissue mass.

Suggested Reading

Hall FM. Incidence of bone sarcoma in Paget’s disease. Radiology 1983;148:865.

Sundarum
M, Khanna G, El-Khoury GY. T1-weighted MR imaging for distinguishing
large osteolysis of Paget disease from sarcomatous degeneration. Skel Radiol 2001;30:378–383.

P.702

Bone Tumors/Tumorlike Conditions: Metastasis

Key Facts

Clinical:
- Pain is the most frequent presenting symptom.
Age: adults
Sex: no sex predilection
Common locations: axial skeleton, proximal long bones
Imaging features:
- Radiographic features: solitary or multiple lesions. Lesions may be lytic, sclerotic, or mixed, depending on primary tumor.
- Radionuclide scans: best screening technique for most metastatic lesions. Seen as areas of increased tracer.
- CT: useful for treatment planning of focal lesions
- MRI: signal intensity varies:
  - Sclerotic, decreased signal on T1- and T2-weighted images
  - Lytic, decreased T1- and increased signal on T2-weighted images
  - Enhancement variable for lytic and
    sclerotic. Diffusion or chemical shift imaging may assist in
    differentiating between benign and malignant compression fractures in
    the spine.
Differential diagnosis:
- Multiple myeloma
- Lymphoma
- Brown tumors

FIGURE 10-37 Radionuclide bone scans of the upper (A) and lower (B) axial skeleton showing multiple foci of increased tracer caused by metastasis.

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FIGURE 10-38
Sagittal T1-weighted image of the lumbar spine demonstrates a burst
fracture of L1 with a large metastatic lesion in L3 extending into the
posterior elements and a third lesion in L4.

Suggested Reading

Simon MA, Karluk MB. Skeletal metastasis of unknown origin: Diagnostic strategy for orthopedic surgeons. Clin Orthop 1983;166:96–103.

Zajick
DC, Morrison WB, Schweitzer ME. Benign and malignant processes: Normal
values and differentiation with chemical shift MR imaging in vertebral
marrow. Radiology 2005;237:590–596.

P.704

Bone Tumors/Tumorlike Conditions: Myeloma

Key Facts

Clinical:
- Myeloma is the most common primary bone
  malignancy. Patients present with local pain and often associated
  weakness and weight loss.
Age: usually more than 60 years; rare in those aged less than 40 years
Sex: Males outnumber females 2:1.
Common locations: skull, axial skeleton, ribs
Imaging features:
- Radiographic features: typically multiple
  small lytic foci. May be a solitary lesion. Bone expansion and soft
  tissue mass common, especially in the ribs.
- CT: generally not performed unless focal lesion
- MRI: lesions low intensity on T1-weighted and high intensity on T2-weighted sequences, although variable. May be normal.
Differential diagnosis:
- Metastasis
- Lymphoma
Treatment: chemotherapy. Surgical intervention for pending pathologic fractures.

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FIGURE 10-39 Multiple myeloma. (A) Lateral radiograph of the skull demonstrates multiple “punched out” lesions (arrows). (B,C) AP radiographs of the humeri and chest wall show multiple rib fractures and multiple lytic lesions in the humeri. (D,E) AP radiographs of the hips and femurs showing focal lytic lesions, osteopenia, and pathologic acetabular fracture (arrow) on the right (D).

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FIGURE 10-40 Sagittal T1-weighted image of the lumbar spine showing diffuse marrow infiltration caused by multiple myeloma.

Suggested Reading

Kyle RA, Elvebrack LR. Management and prognosis of multiple myeloma. Mayo Clin Proc 1976;51:751–760.

P.708

Bone Tumors/Tumorlike Conditions: Lymphoma

Key Facts

Clinical:
- Primary malignant lymphoma accounts for
  less than 5% of malignant bone lesions. Patients present with pain and
  swelling in involved region.
Age: 10 to 80 years of age; most common in those aged in their 60s and 70s
Sex: Males outnumber females 1.8:1.
Common locations: Distal femur and
proximal tibia are most commonly involved followed by the femoral and
humeral shafts. Lesions may involve single or multiple sites.
Imaging features:
- Radiographic features: permeative lytic
  diaphyseal destruction (70%) and mixed in 28%. May be sclerotic as
  well, especially in vertebral bodies. Associated soft tissue mass is
  common (48%). Periosteal reaction in 58% and sequestra in 16%.
- CT: useful to define cortical destruction and soft tissue extension of solitary lesions
- MRI: useful to define cortical destruction and soft tissue extension of solitary lesions. Image features not specific.
Differential diagnosis:
- Ewing sarcoma
- Osteomyelitis
- Metastasis
- Osteosarcoma
Treatment: radiation/chemotherapy

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FIGURE 10-41 Lymphoma. (A) Radiograph of the femur showing a permeative lesion in the upper diaphysis. Sagittal T1-weighted (B) and axial T2-weighted (C) MR images showing the marrow changes and large associated soft tissue mass.

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Suggested Reading

Daffner RH, Lupetin AR, Dask N, et al. MRI in detection of malignant infiltration of bone marrow. AJR Am J Roentgenol 1986;146:353–358.

Mulligan ME, McRae GA, Murphey MD. Imaging features of primary lymphoma of bone. AJR Am J Roentgenol 1999;173:1691–1697.

P.711

Soft Tissue Masses: Lipoma

Key Facts

Clinical:
- Lipomas are the most common soft tissue
  mass. They are composed of mature adipose tissue. Lesions may grow but
  usually stabilize. Lipomas may be superficial or deep. Lesions are
  multiple in 5% to 8% of patients.
Age: 50 to 70 years
Sex: Males slightly outnumber females.
Common locations: deep lipomas—chest
wall, retroperitoneum, hands, and feet. Superficial—back, neck,
shoulder, abdomen, gluteal regions.
Imaging features:
- Radiographic features: Larger lipomas may be seen as well-defined fat density masses.
- CT: fat attenuation, well-defined mass. May contain fibrous septations.
- MRI: fat intensity on all pulse sequences. May have fibrous septa. No enhancement with gadolinium.
Differential diagnosis:
- Low-grade liposarcoma
Treatment: local resection or observe

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FIGURE 10-42 Benign lipoma. Coronal (A) and axial (B) T1-weighted MR images showing a well-defined mass of fat signal intensity along the flexor tendons of the hand.

P.713

Suggested Reading

Dooms
GC, Hricak H, Sollitta RA, et al. Lipomatous tumors and tumors with
fatty components. MR imaging potential and comparison of MR and CT
results. Radiology 1985;157:479–483.

Hosono
M, Kobayashi H, Fujimoto R, et al. Septum-like structures in lipoma and
liposarcoma: MR imaging with pathologic correlation. Skel Radiol 1997;26:150–154.

P.714

Soft Tissue Masses: Liposarcoma

Key Facts

Clinical:
- Liposarcoma is the second most common
  soft tissue sarcoma in adults (16% to 18% of malignant lesions) after
  malignant fibrous histiocytoma. There are five categories: (i) low
  grade (54%); (ii) myxoid liposarcoma (23%), (iii) dedifferentiated
  (10%); (iv) pleomorphic (7%); (v) round cell (5%). Patients present
  with an ill-defined mass.
Age: 40 to 60 years
Sex: Males slightly outnumber females.
Common locations: lower extremities (66%–75%), retroperitoneum (20%–33%)
Imaging features:
- Radiographic features: soft tissue mass. May be partially fat density.
- CT: fat density mass with areas of
  increased attenuation with low-grade liposarcoma. High-grade tumors may
  have little fat density.
- MRI: low grade: fat intensity mass with
  thickened septa and areas of inhomogeneity (decreased signal
  T1-weighted, increased signal T2-weighted image). High grade: Signal
  intensity varies. There may be little fat intensity. Irregular
  enhancement with gadolinium.
Differential diagnosis:
- Lipoma variants
- Malignant fibrous histiocytoma
- Other soft tissue sarcomas
Treatment: excision with or without
postoperative radiation. The incidence of local recurrence is 25% to
45% in the extremities and 90% to 100% in the retroperitoneum.

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FIGURE 10-43 Low-grade liposarcoma. Coronal T1-weighted MR image of the proximal forearm showing areas of low intensity compared with fat (arrowheads). Compare with Figure 10-44.

FIGURE 10-44 Intermediate-grade myxoid liposarcoma in the popliteal fossa. Sagittal T1-weighted (A) and T2-weighted (B) images showing little fat signal on T1-weighted (A) and increased signal intensity on the T2-weighted image (B).

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Suggested Reading

Kransdorf
MJ, Bancroft LW, Peteron JJ, et al. Imaging of fatty tumors.
Distinction of lipoma and well-differentiated liposarcoma. Radiology 2002;224:99–104.

Peterson
JJ, Kransdorf MJ, Bancroft LW, et al. Malignant fatty tumors:
Classification, clinical course, imaging appearance, and treatment. Skel Radiol 2003;32:493–503.

P.717

Soft Tissue Masses: Myxoma (Intramuscular)

Key Facts

Clinical:
- Patients with this benign mass present with palpable soft tissue mass.
Age: 40 to 70 years
Sex: Females outnumber males 2:1.
Common locations: thigh, upper arm and shoulder, gluteal region
Imaging features:
- Radiographic features: none. May see soft tissue mass.
- CT: solid, well-defined intramuscular mass
- MRI: well-defined mass with low intensity on T1-weighted and homogeneous high intensity on T2-weighted images
Differential diagnosis:
- Myxoid liposarcoma
- Rhabdomyosarcoma
- Myxoid lipoma
- Myxoid neurofibroma
Treatment: local excision

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FIGURE 10-45 Myxoma. (A) Coronal T1-weighted, (B) axial proton density, and (C) T2-weighted MR images showing a well-defined lesion with homogeneous low signal on T1-weighted (A) (arrow) and high signal intensity on T2-weighted (C) images.

Suggested Reading

Peterson KK, Renfrew DL, Fedderson RM, et al. Magnetic resonance imaging of myxoid-containing tumors. Skel Radiol 1991;20:245–250.

P.719

Soft Tissue Masses: Hemangioma

Key Facts

Clinical:
- Hemangiomas are common (7% of soft tissue
  tumors) and represent the most common tumor in children. There are many
  variants, but most are classified as capillary or cavernous in type.
  Lesions may change in size and can be painful. There are multiple
  associated syndromes.
- Maffucci: multiple enchondromas and soft tissue cavernous hemangiomas
- Klippel-Trenaunay-Weber: cutaneous hemangiomas, bone and soft tissue hypertrophy, varicose veins
- Osler-Weber-Rendu: hereditary hemorrhagic telangiectasia
- Kasabach-Merritt: large hemangiomas and thrombocytopenic purpura
- Sturge-Weber: facial port wine nevus, seizures, glaucoma, buphthalmos, and mental retardation
- Von Hippel-Lindau: central nervous system
  hemangioblastomas, retinal angiomas, renal and pancreatic cysts, renal
  cell carcinoma, pheochromocytomas
Age: less than 30 years (90% present by 30 years of age)
Sex: no sex predilection
Common locations: superficial—head and neck. Deep—lower extremities.
Imaging features:
- Radiographic features: normal.
  Phleboliths may be seen, especially in cavernous hemangiomas. Bone
  changes in up to 33% of patients (periosteal reaction, cortical
  erosion).
- CT: phlebolith calcifications. Vessels identified with intravenous contrast.
- MRI: Serpiginous vessels using
  conventional spin-echo sequences or MR angiography. Cavernous
  hemangiomas may have large amounts of fat and nonvascular tissue, and
  they are larger than capillary hemangiomas.
Differential diagnosis:
- Lipoma
- Angiosarcoma
Treatment: observation. Embolization or resection in selected cases.

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FIGURE 10-46 Hemangioma. (A) Axial T2-weighted and (B)
coronal gradient echo MR images demonstrating deep and superficial
hemangiomas in the distal thigh with markedly increased signal
intensity in serpiginous vascular structures.

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Suggested Reading

Beutow PC, Kransdorf MJ, Mosen RP, et al. Radiographic appearance of hemangioma with emphasis on MR imaging. AJR Am J Roentgenol 1990;154:563–567.

Sung MS, Kang HS, Lee HG. Regional bone changes in deep soft tissue hemangiomas: Radiographic and MR features. Skel Radiol 1998;22:205–210.

Vilanova JC, Barcelo J, Smirniotopoulos JG, et al. Hemangioma from head to toe: MR imaging with pathologic correlation. Radiographics 2004;24:367–385.

P.722

Soft Tissue Masses: Lymphangioma

Key Facts

Clinical:
- The lesion is made up of lymphatic
  channels with fat and other stromal elements. Cause is unknown, but may
  be congenital or related to obstruction. Capillary, cavernous, and
  cystic varieties exist; the latter are most common.
Age: birth to 30 years
Sex: no sex predilection
Common locations: cystic—head and neck. Other—mediastinum, retroperitoneum, extremities
Imaging features:
- Radiographic features: soft tissue mass. Calcification rare.
- CT: soft tissue mass. Vessel-like structures in fatty tissue.
- MRI: cystic-type low signal intensity on
  T1-weighted and homogeneous high signal intensity on T2-weighted
  images. Serpiginous vessels may be difficult to differentiate from
  veins or arteries of other vascular lesions.
Differential diagnosis:
- Hemangioma
- Cyst or ganglion
Treatment: resection, depending on extent and risks

P.723

FIGURE 10-47 Lymphangioma. Axial (A) and coronal (B,C) images of the lower extremities demonstrating low signal intensity dilated lymphatic vessels on the right.

Suggested Reading

Siegel MF, Glazer HS, St. Amour TE, et al. Lymphangiomas in children. MR imaging. Radiology 1989;170:467–470.

P.724

Soft Tissue Masses: Benign Peripheral Nerve Sheath Tumor

Key Facts

Clinical:
- Benign peripheral nerve sheath tumors
  include neurofibromas and schwannomas. Symptoms are similar—slowly
  growing mass. Pain and paresthesias may be present.
Age: 20 to 50 years
Sex: no sex predilection
Common locations: neurofibroma—cutaneous
nerves. Schwannoma— head, neck, flexor surface of extremities,
mediastinum, retroperitoneum
Imaging features:
- Radiographic features: typically none
- CT: well-defined soft tissue mass
- MRI: neurofibroma—target appearance on
  T2-weighted images. Low-intensity center with peripheral higher
  intensity. Central zone enhances on T1-weighted postgadolinium images.
  Schwannoma—similar to neurofibroma in 46% or low intensity on
  T1-weighted and high intensity on T2-weighted images. Nerve visible
  along or inside the mass in 90%.
Differential diagnosis:
- Cyst
- Myxoma
- Soft tissue sarcoma
Treatment: resection of schwannoma. Neurofibroma cannot be successfully resected without sacrificing the underlying nerve.

FIGURE 10-48 Schwannoma. Axial proton density (A) and T2-weighted (B) images showing a well-defined lesion with high intensity on the T2-weighted image.

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FIGURE 10-49 Neurofibroma. (A)
Axial T2-weighted image showing a high-intensity lesion with central
low intensity (target appearance) characteristic of neurofibroma. (B) Axial post-contrast T1-weighted image showing central enhancement.

Suggested Reading

Varma DGK, Moulopulos A, Sara AS, et al. MR imaging of extracranial nerve sheath tumors. J Comput Assist Tomogr 1992;16:448–453.

P.726

Soft Tissue Masses: Malignant Peripheral Nerve Sheath Tumor

Key Facts

Clinical:
- Malignant peripheral nerve sheath tumors
  account for 6% to 10% of all soft tissue sarcomas. Half occur in
  patients with neurofibromatosis. Patients present with enlarging masses
  with or without pain.
Age: 20 to 50 years
Sex: no sex predilection
Common locations: major nerves or plexus; therefore, upper and lower extremities or trunk
Imaging features:
- Radiographic features: normal or soft tissue mass
- CT: soft tissue mass in or near major neural structure
- MRI: irregular margins with signal inhomogeneity on T2-weighted images. Irregular bone destruction not uncommon.
Differential diagnosis:
- Malignant fibrous histiocytoma
- Leiomyosarcoma
- Synovial sarcoma
Treatment: wide excision. Five-year
survival is only 15% to 40%. Prognosis worse if the lesion is larger
than 5 cm and in patients with neurofibromatosis.

P.727

FIGURE 10-50 Malignant nerve sheath tumor. Coronal T1-weighted (A) and T2-weighted (B)
images showing a large mass with nerve enlargement at its margins. The
mass is high intensity on T2 with a large low-intensity central zone.
T1-weighted contrast-enhanced image (C) showing peripheral enhancement of the tumor and adjacent nerve.

Suggested Reading

Ducetman BS, Scheithaurer BW, Piepgras DG, et al. Malignant nerve sheath tumors. A clinicopathological study of 120 cases. Cancer 1986;57:2006–2021.

Lin
J, Martel W. Cross-sectional imaging of peripheral nerve sheath tumors:
Characteristic signs on CT, MR imaging, and sonography. AJR Am J Roentgenol 2001;176:75–82.

P.728

Soft Tissue Masses: Deep Fibromatosis (Desmoid Tumor)

Key Facts

Clinical:
- Fibromatoses may be superficial, which
  are diagnosed clinically, or deep, which often require imaging for
  detection and diagnosis. Although benign lesions, they have an
  aggressive clinical behavior. Multiple lesions are reported in 10% to
  15% of cases. Patients present with a soft tissue mass.
Age: adolescent to 40 years
Sex: no sex predilection
Common locations: most in lower extremity, upper extremity, shoulder
Imaging features:
- Radiographic features: Soft tissue mass may be evident. Pressure erosions of adjacent bone (6% to 16%).
- CT: poorly defined soft tissue mass. Good for early bone involvement.
- MRI: Variable portions to entire mass may
  have low signal intensity on all pulse sequences because of fibrous
  tissue. More often, areas of intermediate signal intensity on
  T2-weighted images also are present. Irregular margins. Neurovascular
  and bone involvement easily identified.
Differential diagnosis:
- Fibrosarcoma
- Malignant fibrous histiocytoma
Treatment: wide excision when possible. Recurrence rate greater than 75%.

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FIGURE 10-51 Desmoid tumor. Axial T1-weighted (A) and axial (B) and sagittal (C)
T2-weighted images showing a poorly defined mass with areas of low
signal intensity on both sequences characteristic of a fibrous lesion.
The lesion encases the metatarsals.

Suggested Reading

Lee JC, Thomas JM, Phillips S, et al. Aggressive fibromatosis: MRI features with pathologic correlation. AJR Am J Roentgenol 2006;186:247–254.

Sundaram
M, McGuire MH, Schajowicz F. Soft tissue masses: Histologic bases for
decreased signal (short T2) on T2-weighted MR images. AJR Am J Roentgenol 1987;148:1247–1250.

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Soft Tissue Masses: Elastofibroma

Key Facts

Clinical:
- Elastofibroma is a tumorlike mass
  resulting from friction between the scapula and chest wall. The lesion
  is not uncommon and is found in 24% of females and 11% of males at
  autopsy when patients are aged more than 55 years. Half are
  asymptomatic.
Age: more than 55 years; mean 70 years
Sex: Females outnumber males 2:1.
Common locations: Between scapula and chest wall in 99%; up to 67% are bilateral.
Imaging features:
- Radiographic features: normal. Rarely, scapula displaced.
- CT: soft tissue mass. Location more specific for diagnosis than imaging features.
- MRI: soft tissue mass with well-defined
  margins. Signal intensity similar to muscle on T1- and T2-weighted
  images with scattered areas of fat intensity. Irregular enhancement
  with gadolinium.
Differential diagnosis:
- Fibroma
- Desmoid
Treatment: surgical excision

FIGURE 10-52 Elastofibroma. Axial T2-weighted MR image showing a muscle density infrascapular lesion (asterisk) with linear areas of fat density.

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FIGURE 10-53 Axial CT images demonstrate a subscapular mass (arrow) on the right with areas of fat infiltration.

Suggested Reading

Kransdorf MJ, Meis JM, Montgomery E. Elastofibroma. MR and CT appearance with radiological-pathological correlation. AJR Am J Roentgenol 1992;159:575–579.

P.732

Soft Tissue Masses: Ganglion

Key Facts

Clinical:
- Ganglia are often asymptomatic,
  well-defined juxta-articular lesions. Some may present with pain. Most
  are less than 2 cm in size.
Age: 25 to 45 years
Sex: much more common in females than in males
Common locations: Wrist and hand most common, but occur around any articular location.
Imaging features:
- Radiographic features: normal or small soft tissue mass
- CT: well-defined soft tissue mass with fluid density
- MRI: well-defined lesion with uniformly
  high intensity on T2-weighted and low signal intensity on T1-weighted
  sequences. May vary if complicated by hemorrhage or thick proteinaceous
  debris. Wall enhances with gadolinium.
Differential diagnosis:
- Synovial sarcoma
- Nerve sheath tumor
Treatment: aspiration or, more often, resection

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FIGURE 10-54 Ganglion cyst. Axial (A) and coronal (B) T2-weighted images showing a well-defined high signal intensity lesion (arrows). (C) Post-contrast T1-weighted image showing cyst wall enhancement (arrow).

Suggested Reading

Feldman F, Surgson SD, Staron RB. Magnetic resonance imaging of para-articular and ectopic ganglia. Skel Radiol 1989;18:353–358.

P.734

Soft Tissue Masses: Giant Cell Tumor of Tendon Sheath

Key Facts

Clinical:
- Giant cell tumors of the tendon sheath
  may be focal or diffuse. The localized lesion is most common in the
  hand, usually the flexor tendons. Patients present with a slow-growing
  soft tissue mass.
Age: 30 to 50 years
Sex: Females outnumber males.
Common locations: hand; less commonly, foot, knee, hip
Imaging features:
- Radiographic features: soft tissue mass. Bone erosion in 15%.
- CT: Soft tissue mass associated with tendon. Bone involvement easily appreciated.
- MRI: Mass associated with a tendon and
  low intensity (muscle density) on T1-weighted and intermediate to low
  intensity on T2-weighted sequences. Irregular enhancement with
  gadolinium.
Differential diagnosis:
- Granuloma
- Fibroma
Treatment: resection. Recurrence occurs in up to 20%.

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FIGURE 10-55 Giant cell tumor of the tendon sheath. AP (A) and lateral (B) radiographs demonstrate a soft tissue mass (open arrows) with bone erosion (arrowheads). Sagittal T2-weighted (C) image shows intermediate and low signal intensity with bone erosion. There is irregular enhancement (D) after contrast.

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Suggested Reading

Jelinek JS, Kransdorf MJ, Utz JA, et al. MR imaging of giant cell tumor of the tendon sheath. AJR Am J Roentgenol 1994;162:919–922.

P.738

Soft Tissue Masses: Hematoma

Key Facts

Clinical:
- Patients present with history of trauma
  or mass that may be painful. Hematomas may be acute (hours, days),
  subacute (3 weeks to 3 months), or chronic (more than 3 months).
Age: occurs at any age
Sex: no sex predilection
Common locations: lower extremities
Imaging features:
- Radiographic features: normal or soft tissue mass
- CT: Soft tissue mass with areas of increased attenuation caused by blood. Usually well-defined margins.
- MRI
  - Acute: muscle density on T1-weighted and variable on T2-weighted sequences.
  - Subacute: increased signal on T1- and T2-weighted sequences. May have low-intensity fibrous rim.
  - Chronic: similar to subacute
Differential diagnosis:
- Sarcoma
- Abscess
Treatment: Observe or resect, depending on location and symptoms.

P.739

FIGURE 10-56 Acute hematoma. (A) T1-weighted axial MR image showing a muscle density mass (arrows). (B) The hematoma is high intensity on the T2-weighted image.

Suggested Reading

Aoki T, Norkata H, Watanabe H, et al. The radiologic findings of chronic expanding hematoma. Skel Radiol 1999;28:396–401.

P.740

Soft Tissue Masses: Myositis Ossificans

Key Facts

Clinical:
- Patients may or may not have a history of trauma. Pain, tenderness, and soft tissue mass are common findings.
Age: children, adults
Sex: no sex predilection
Common locations: Eighty percent are in the large muscles of the extremities, especially lower extremities.
Imaging features:
- Radiographic features: faint soft tissue calcification within 2 to 6 weeks. May have well-defined bony margins by 8 weeks.
- Separated from periosteum by lucent zone.
- CT: Characteristic feature is peripheral ossification.
- MRI: Features vary with age.
- Early: low intensity on T1-weighted and high intensity on T2-weighted images. Soft tissue edema with similar pattern.
- Late: peripheral rim of low intensity on
  all sequences. Irregular areas of increased signal intensity on
  T2-weighted sequences and fluid–fluid levels centrally. Later, central
  signal intensity similar to fat on all sequences or areas of low
  intensity caused by ossification or fibrosis.
Differential diagnosis:
- Parosteal sarcoma
- Juxtacortical osteosarcoma
Treatment: resection

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FIGURE 10-57 Myositis ossificans of intermediate age. (A) Radiograph showing an area of ossification near the proximal radius. (B) Proton-density MR image showing a lesion with fluid–fluid levels. Mineralization is seen as a subtle rim of decreased signal.

Suggested Reading

DeSmet AA, Norris MA, Fisher DR. Magnetic resonance imaging of myositis ossificans. Skel Radiol 1992;21:503–507.

P.742

Soft Tissue Masses: Malignant Fibrous Histiocytoma

Key Facts

Clinical:
- Malignant fibrous histiocytoma is the
  most common soft tissue sarcoma in adults more than 45 years of age.
  Patients usually present with a painless enlarging lower extremity mass.
Age: 45 to 70 years
Sex: Males outnumber females 2:1.
Common locations: thigh, lower extremity, upper extremity, and retroperitoneum in decreasing frequency
Imaging features:
- Radiographic features: soft tissue mass. Rarely calcifies.
- CT: soft tissue mass with variable enhancement after intravenous contrast
- MRI: irregular margins with low intensity
  on T1-weighted and inhomogeneous high signal intensity on T2-weighted
  sequences. Variable enhancement with gadolinium.
Differential diagnosis:
- Pleomorphic liposarcoma
- Fibrosarcoma
- Desmoid tumor
Treatment: wide excision. Radiation and chemotherapy as adjuvant or palliative measures

P.743

FIGURE 10-58 Malignant fibrous histiocytoma. (A) Radionuclide bone scan showing increased tracer in the soft tissues along the distal left femur (arrow). Coronal T1-weighted (B) and axial T2-weighted (C) images showing a large inhomogeneous lesion with areas of hemorrhage.

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Suggested Reading

Weiss SW, Goldblum JR. Enzinger and Weiss soft tissue tumors, 4th ed. St. Louis: Mosby; 2001:535–570.

P.745

Soft Tissue Masses: Synovial Sarcoma

Key Facts

Clinical:
- Synovial sarcoma is fairly common,
  accounting for 10% of soft tissue sarcomas. Patients present with a
  slow-growing, often innocent-appearing mass. The mass typically is near
  a joint and associated with a tendon sheath, bursa, or fascial plane.
  Metastasis is present at time of diagnosis in 25% of patients. Pain
  also is commonly present.
Age: 15 to 40 years
Sex: Males slightly outnumber females.
Common locations: extremities near larger joints, especially the knee
Imaging features:
- Radiographic features: normal or well-defined soft tissue mass. Calcification occurs in 33%. Bone involvement occurs in 20%.
- CT: well-defined soft tissue mass near a joint. Subtle calcification is easily appreciated.
- MRI: inhomogeneous signal on T2-weighted
  sequences. May have cystic appearance and fluid–fluid levels.
  Calcifications seen as areas of low intensity on all sequences.
Differential diagnosis:
- Benign cyst
- Hematoma
- Epithelioid sarcoma
- Malignant nerve sheath tumor
Treatment: wide excision, adjuvant radiation therapy

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FIGURE 10-59 Synovial sarcoma. (A) Radiograph showing a large calcified mass in the thigh. (B) CT image showing a large calcified soft tissue mass in the medial thigh. Coronal T1-weighted (C) and T2-weighted (D)
MR images showing a large inhomogeneous mass. The calcifications are
seen as low-intensity regions in the medial aspect of the mass with
hemorrhage seen inferiorly.

Suggested Reading

Morton MJ, Berquist TH, McLeod RA, et al. MR imaging of synovial sarcoma. AJR Am J Roentgenol 1990;156:337–340.

P.747

Soft Tissue Masses: Rhabdomyosarcoma

Key Facts

Clinical:
- Rhabdomyosarcoma is the most common soft
  tissue sarcoma in children aged less than 15 years, but also is common
  in adolescents and young adults. Patients present with soft tissue mass
  when extremities are involved. Metastasis is present at the time of
  diagnosis in 20%.
Age: children, young adults
Sex: Males slightly outnumber females.
Common locations: head, neck, genitourinary tract, retroperitoneum, and extremities, in decreasing order of frequency
Imaging features:
- Radiographic features: vary with
  location. Most poorly defined masses. Lower genitourinary tract
  (botryoid sarcoma) may look like multiple cysts in 25% of cases.
- CT: similar to radiographic
- MRI: variable. Typically, high signal
  intensity on T2-weighted and low on T1-weighted sequences. May be
  inhomogeneous on T2-weighted sequences, with poorly defined margins.
Differential diagnosis:
- Transitional cell (bladder)
- Leiomyosarcoma
- Lymphoma
Treatment: wide excision when possible. Varies with location. Recurrence and metastasis are common.

P.748

FIGURE 10-60 Rhabdomyosarcoma in a 3-month-old girl. Axial T2-weighted (A) and coronal gradient-echo (B) weighted MR images showing a high signal intensity muscle mass caused by an embryonal rhabdomyosarcoma.

Suggested Reading

Weis SW, Goldblum JR. Enzinger and Weiss’s soft tissue tumors, 4th ed. St. Louis: Mosby; 2001:785–836.