Ovid: Pediatrics

Editors: Tornetta, Paul; Einhorn, Thomas A.; Cramer, Kathryn E.; Scherl, Susan A.
Title: Pediatrics, 1st Edition
> Table of Contents > Section III: – Specialty Clinics > 23 – TUMORS

Bulent Erol
John P. Dormans
Lisa States
Bruce Pawel
Pediatric musculoskeletal tumors (MSKTs) are uncommon;
although when they occur, they usually are benign. Early detection of a
malignant MSKT may not only make the difference between life and death,
but also may allow for successful limb salvage surgery rather than
amputation of the limb. The primary bone and soft tissue tumors of
childhood can be classified based on their tissue origin (Table 23-1).
This chapter is not intended as an exhaustive survey of childhood
musculoskeletal neoplasm. It will cover general principles of MSKT
diagnosis and treatment, and some of the more common individual
A thorough evaluation of the history of the patient and
physical examination are the basis for determining the correct
diagnosis and therapy. That type of tumors seen in children with an
MSKT are presented in Box 23-1. The age of the
patient is important in establishing a differential diagnosis, because
certain tumors tend to occur in certain age groups (Table 23-2).



Bone tumors

Bone origin

Osteoid osteoma, osteoblastoma, osteosarcoma

Cartilaginous origin

Osteochondroma, chondroblastoma, chondromyxoid fibroma, enchondroma, periosteal chondroma

Fibrous origin

Nonossifying fibroma, fibrous dysplasia, osteofibrous dysplasia, desmoplastic fibroma


Unicameral bone cyst, aneurysmal bone cyst, giant cell tumor

Langerhans cell histiocytosis, Ewing sarcoma; musculoskeletal manifestations of leukemia, bone lymphomas

Metastatic tumors

Neuroblastoma, retinoblastoma, hepatoblastoma

Soft tissue tumors

Vascular tumors

Hemangioma, vascular malformations

Nerve origin

Neurolemmoma, neurofibroma, malignant peripheral nerve sheath tumor

Fibrous origin

Fibromatosis, fibrosarcoma

Muscular origin



Synovial sarcoma, primitive neuroectodermal tumors, ganglion and synovial cyst

Imaging Studies
  • Plain radiographs give the most detailed information about skeletal lesions.
    • □ Orthogonal views showing the entire lesion are necessary.
    • □ 30% to 40% of a bone must be destroyed before lytic changes can be seen in plain radiographs.
    • □ It is often difficult to see soft tissue tumors and soft tissue extension from bony neoplasms with plain radiographs.
  • P.251
  • Magnetic resonance imaging (MRI) best demonstrates the soft tissue anatomy and intramedullary extension of the tumor.
  • MRI remains the modality of choice for
    staging, for evaluating response to preoperative chemotherapy, and for
    long-term follow-up of most bone and soft tissue sarcomas.
  • Computed tomography (CT) can demonstrate
    bone destruction and mineralization and is particularly helpful for
    bone tumors involving axial skeleton.
  • A total body radionuclide bone scan will
    evaluate the biologic activity of the primary bone lesion and search
    for other lesions within the skeletal system.

Age (yr)




Langerhans cell histiocytosis

Metastatic tumors



Ewing sarcomab



Unicameral bone cyst


Aneurysmal bone cyst


Nonossifying fibroma

Ewing sarcoma

Fibrous dysplasia


Osteoid osteoma

Langerhans cell histiocytosis


Fibrous dysplasia


Osteoid osteoma

Ewing sarcoma



Aneurysmal bone cyst

Synovial cell sarcoma



Osteofibrous dysplasia

a Musculoskeletal tumors are more common in boys than girls.

b Ewing sarcoma is prevalent in Caucasians and rare in African Americans.

Features of Bony Lesions
  • Location (Box 23-2)
    • □ Epiphyseal, metaphyseal, or diaphyseal
    • □ Central or eccentric
  • Destruction of bone (Fig. 23-1)
    • □ Geographic: typical of slow-growing, benign lesions
    • □ Moth-eaten (multiple, small, often
      clustered lytic areas) and permeative (ill-defined, very small oval
      radiolucencies or lucent streaks) typical of rapidly growing,
      infiltrating tumors
  • Replacement of bone
  • Response of bone
    • □ “Walled off” by cortex: static lesion
    • □ Destroyed cortex and soft tissue mass: aggressive lesion
  • Periosteal reaction (Fig. 23-2)
    • □ Continuous: benign
    • □ Interrupted: malignant
    • □ Sunburst (“hair-on-end”)
    • □ Lamellated (onion-skin).
    • □ Reactive cuff (Codman triangle)
Staging of lesions that appear to be malignant is required prior to biopsy. Box 23-3
outlines staging recommendations. Biopsy should be the last step in the
evaluation of a patient with a bone or soft tissue sarcoma and should
be performed following completion of the radiographic staging and
preoperative consultation with the oncologist, radiologist,
pathologist, and surgeon. After staging studies are completed, a
differential diagnosis can be formulated. Box 23-4 summarizes the basic principles that should be followed in performing an incisional biopsy.

Figure 23-1
Different patterns of bone destruction. (Adapted from Madewell JE,
Ragsdale BD, Sweet DE. Radiologic and pathologic analysis of solitary
bone lesions. Part I. internal margins. Radiol Clin North Am

Figure 23-2
Different patterns of periosteal reaction. (Adapted from Ragsdale BD,
Madewell JE, Sweet DE. Radiologic and pathologic analysis of solitary
bone lesions. Part II. periosteal reaction. Radiol Clin North Am
Osteoid Osteoma
  • Nidus of osteoid tissue is surrounded by dense reactive bone (Fig. 23-4).
  • 10% of benign bone tumors.
  • The femur is the single most common site of involvement.
  • More than half are found in either the femur or the tibia.
  • Pain is typically worse at night.
  • Relieved by salicylates and nonsteroidal antiinflammatory drugs (NSAIDs).
  • The posterior elements of the spine may also be involved.
Radiographic and Histologic Features
See Table 23-4.
Natural History and Treatment
  • Burns out with time (years)
  • Standard treatment is complete removal of the nidus by open surgical or CT-guided percutaneous techniques.
  • “Giant osteoid osteoma” (Fig. 23-5)
  • Less than 1% of primary bone tumors
  • Predilection for the posterior elements of the spine
  • Gradually increasing pain
  • Not totally relieved with salicylates or NSAIDs
Radiographic and Histologic Features
See Table 23-4.

Figure 23-4 Osteoid osteoma. (A)
Lateral radiograph of the proximal leg shows a well-circumscribed lytic
lesion in the posterior cortex of the proximal tibia. There is
significant cortical thickening surrounding the lesion. The cortical
thickening has caused widening of the tibia. (B)
Axial computed tomography image demonstrates the cortical location of
the lesion. There is a dense, central nidus surrounded by a lucent rim.
Note the extensive cortical thickening. (C)
Photomicrograph of the lesion shows a nidus composed of irregular woven
bone trabeculae within a background fibroblastic stroma rich in blood
Natural History and Treatment
  • Excised surgically by extended intralesional curettage or en bloc excision
  • Most common malignant primary bone tumor of childhood
  • Classified by whether it is primary
    (occurring with no evidence of a preexisting lesion or prior treatment
    of the bone, such as radiation therapy) or secondary, and by the site
    of origin, either within the bone (intramedullary) or on the surface
  • More than 95% of osteosarcomas involving children and young adults are primary.
  • Osteosarcomas generally have complex
    karyotypic abnormalities without chromosomal translocations. Several
    nonrandom deletions have been identified, however. The two most obvious
    gene deletions in osteosarcomas are located on chromosome 13 and 17,
    which are the chromosomes containing tumor suppressor genes—
    retinoblastoma (RB1) and p53 genes, respectively.
High-Grade Intramedullary Osteosarcoma (Conventional Osteosarcoma)
  • 85% of all forms of osteosarcoma
  • Occurs at the metaphyseal ends of the long bones, which have the greatest growth potential
  • 50% are located in the distal femur or proximal tibia.
  • P.256
  • The proximal humerus, proximal femur, and pelvis are the next most common sites.
  • Pain and swelling are the most common presenting symptoms.
  • Approximately 15% of patients with
    high-grade intermedullary osteosarcoma present with clinically evident
    metastases, most commonly in the lungs, but also in other bone
    locations and brain.
  • Metastases at diagnosis indicate poor prognosis.


Osteoid Osteoma



Gross (macroscopic)

Round or oval, reddish brown, most ~ 1 cm diameter

Similar, but larger than osteoid osteoma (most 2-6 cm)

Histologic (microscopic)

Distinct demarcation between nidus and surrounding reactive bone

Interlacing network of immature bone and bony trabeculae, with focal areas of osteoblastic and osteoclastic activity

Demarcation is not significant

Interlacing woven bone lined by osteoblasts within a fibrovascular stroma


Plain radiography

Long bone; metaphysis or diaphysis

Spine; posterior elements

Small (~ 1 cm), round-elliptical, lucent, intracortical (mostly) lesion surrounded by extensive reactive sclerotic bone

Spine; posterior elements

Long bone; metaphysis or diaphysis

2-6 cm, round-elliptical lytic lesion surrounded by moderate reactive sclerotic bone

Computed tomography

Thin (1-2 mm) sections; provides exact localization of the nidus

Figure 23-5 Osteoblastoma. (A)
On anteroposterior radiograph of the elbow, a well-circumscribed lytic
lesion with sclerotic borders is seen in the metaphysis of the distal
humerus. Note the significant cortical thickening. The location is
unusual but the features are classic for osteoblastoma. (B)
Axial computed tomography image shows the typical central nidus of bone
formation within the lytic lesion. Note the diffuse, reactive cortical

Radiographic Features
  • Plain radiographs: metaphyseal lesion
    involving the medullary canal with mixed lytic (radiolucent) and
    blastic (radiodense) activity
  • Sunburst periosteal reaction with a Codman triangle (Fig. 23-6A)
  • Soft tissue mass which may contain sclerotic foci (tumor bone formation) is also a common finding
  • Bone scan shows increased uptake in the area of the tumor.
  • MRI is the method of choice for evaluating the tumor and its relationship to adjacent structures.
Figure 23-6 High-grade intramedullary osteosarcoma (conventional osteosarcoma). (A)
Lateral radiograph of the knee shows a lacy, spiculated mass of new
bone formation in the metaphysis of the distal femur. Irregular, patchy
sclerosis is seen in the metaphysis and epiphysis. (B)
On sagittal T2-weighted image a heterogenous mass is seen in the marrow
of the metaphysis and epiphysis with extension into the soft tissues
posterior to the femur. (C)
Photomicrograph (high-power magnification) of the lesion reveals a
cellular neoplasm with scattered pleomorphic and bizarre nuclei. Focal
osteoid production is evident.
Histologic Features
  • Several histologic subtypes, all with the
    same prognosis, and characterized by the formation of osteoid tissue or
    new bone by the neoplastic cells
  • Osteoblastic subtype is the most common (50%).
  • Highly pleomorphic spindle-shaped and polyhedral tumor cells (see Fig. 23-6C).
  • Nuclear hyperchromasia, abundant mitotic activity, and atypical mitotic figures.

  • Combination of chemotherapy and surgical resection of the tumor.
  • Current standard protocols consist of
    preoperative multiagent neoadjuvant chemotherapy, followed by surgical
    resection, and subsequent additional chemotherapy (adjuvant
    chemotherapy) (Box 23-3).
  • Osteosarcoma responds poorly to radiation therapy.
  • Neoadjuvant chemotherapy is to treat
    micrometastatic disease, to cause necrosis of the primary tumor and to
    decrease the primary tumor size in order to facilitate limb salvage
  • Following surgical resection, adjuvant chemotherapy is continued to eliminate any micrometastases still present.
  • A good response to chemotherapy, usually
    defined as greater than 90% necrosis of the tumor (detected in the
    resection specimen), is associated with higher survival rates than a
    lesser response.
  • Surgery is the mainstay of local control of osteosarcoma.
    • □ Excision of the tumor with wide
      surgical margins, which can be achieved through limb salvage or
      amputation, is the goal of the surgery.
    • □ Currently, limb salvage is possible in most patients with an extremity osteosarcoma.
    • □ Limb salvage reconstruction includes
      techniques such as endoprosthetic reconstruction, allograft
      reconstruction, or rotationplasty reconstruction.
    • □ In some locations, such as the fibula and clavicle, no bony reconstruction is necessary.
  • The indications for an amputation are
    inability to achieve wide surgical margins, a grossly displaced
    pathologic fracture, a tumor that enlarges during preoperative
    chemotherapy, and neurovascular bundle involvement that cannot be
    appropriately addressed with reconstructive techniques.
Surface or Juxtacortical Osteosarcoma
The term juxtacortical is a
general designation for a group of osteosarcomas that arise on the
surface of a bone. Three subtypes are recognized; parosteal,
periosteal, and high-grade. The great majority of juxtacortical
osteosarcomas are low-grade tumors (parosteal osteosarcoma), although
there are moderately (periosteal osteosarcoma) and highly malignant
(high-grade surface osteosarcoma) variants.
  • Low-grade juxtacortical osteosarcomas (parosteal and periosteal) should be treated with wide excision.
    • □ Although the metastatic potential of
      these low-grade surface lesions is much lower than conventional
      osteosarcoma, these are locally aggressive malignant tumors and
      inadequate resection will result in recurrence.
    • □ Repeated local recurrence also may result in progression of the tumor to a more aggressive, high-grade lesion.
  • High-grade surface osteosarcomas require aggressive treatment similar to that of conventional osteosarcoma.
  • Most common skeletal tumor
  • 20% to 50% of benign bone tumors and 10% to 15% of all bone tumors
  • Involves the metaphysis of long bones, particularly around the knee (40% of lesions) and the proximal humerus
  • A firm mass, usually of long duration, adjacent to a joint
  • Pain may result due to irritation of overlying soft tissues by the lesion.
Radiographic Features
  • Plain radiographs show a bony projection
    composed of a cortex continuous with that of the underlying bone and a
    spongiosa, similarly continuous.
  • The lesions consist of a cartilaginous cap with a broad (sessile osteochondroma) or narrow (pedunculated osteochondroma) base (Figs. 23-7 and 23-8).
  • CT can demonstrate the continuity of
    cancellous portions of the lesion and the host bone and the thickness
    of the noncalcified cap (it is usually less than 3 mm).
  • CT may be useful in differentiating atypical osteochondromas from malignant lesions.
Natural History and Treatment
  • Malignant transformation of osteochondroma to chondrosarcoma occurs in less than 1% of solitary lesions.
  • In a skeletally mature patient, a growing
    lesion with a thick cartilaginous cap in an axial location (i.e.,
    pelvis, scapula) is highly suggestive of this complication.
  • P.259
  • Asymptomatic osteochondromas do not require any treatment.
  • For osteochondromas that cause pain or
    neurovascular compromise (i.e., lesions in the popliteal fossa) or are
    cosmetically unappealing, surgical excision is indicated.
    • □ A potential complication of surgery is
      injury to an adjacent physis, which may lead to deformity, if the
      lesion is in close proximity to the growth plate.
  • The incidence of local recurrence after
    surgical excision is very low (less than 2%). The entire cartilaginous
    cap should be removed to prevent recurrence.
Figure 23-7 Osteochondroma. A patient with a pedunculated osteochondroma. Note the narrow pedicle.
Figure 23-8 Photomicrograph of osteochondroma, demonstrating a thick cartilaginous cap overlying cancellous bone.
Hereditary Multiple Exostosis
  • Autosomal dominant disorder with a variable penetrance
  • Associated with tumor-suppressor genes, termed exostosin (EXT) genes
  • After the age of 30, patients with this disorder have an increased risk of developing a secondary chondrosarcoma.
  • Excision of one or more exostoses often is necessary.
Figure 23-9 Chondroblastoma. (A)
Anteroposterior radiograph of the shoulder shows a well-circumscribed,
lytic lesion in the lateral epiphysis of the humerus. The lesion does
not cross the physis. (B) Photomicrograph
of the lesion demonstrates tumor cells that are uniform, closely packed
and polyhedral, and are focally enveloped by a lace-like, lightly
calcified chondroid matrix.
  • 1% of all benign bone tumors
  • Occurs primarily in the epiphysis of the growing skeleton
  • The most common sites are the proximal humerus, proximal and distal femur, and proximal tibia.
  • Pain, swelling, and limited motion are usually localized to the adjacent joint.
Radiographic Features
  • Plain radiographs show a well-marginated, radiolucent lesion, usually with a sclerotic rim of bone (Fig. 23-9A). The lesion may have small foci or calcifications.
  • Bone scan shows increased uptake.
  • Chest radiography or CT should be performed, because chondroblastoma is one of the benign tumors that can have lung metastasis.
Histologic Features
  • Small cuboidal cells (chondroblasts) closely packed together to give the appearance of a cobblestone street (see Fig. 23-9B).
    There are areas with varying amounts of amorphous matrix that often
    contains streaks of calcification (“chicken-wire” calcification), and
    there are numerous multinucleated giant cells.
Natural History and Treatment
  • Chondroblastoma is a benign, but locally aggressive lesion (Box 23-5).
  • P.260
  • Most patients are close to skeletal
    maturity and damage to the growth plate is not a major concern.
    However, the lesions may progress and invade the joint.
  • Chondroblastomas should be treated when detected.
  • Intralesional extended curettage is the initial treatment of choice.
  • Recurrence rates of approximately 10% have been reported after intralesional excision.
  • The majority of recurrences are adequately addressed with a second curettage. Rarely, recurrent lesions require en bloc excision.
  • In rare cases of severe bone destruction or recurrence, wide resection and segmental reconstruction sometimes is indicated.
  • Benign tumor of mature hyaline cartilage
  • 10% of benign bone tumors
  • Usually present as solitary lesions
  • Short tubular bones of the hand and foot are common sites.
  • Most present with a pathologic fracture
    through the lesion, or as an incidental finding on a radiograph taken
    for another reason.
Figure 23-10 Enchondroma. (A)
Anteroposterior radiograph of the ulnar three digits of the hand shows
an expansile, lytic lesion involving the diaphysis of the fifth
metacarpal with extension into the distal metaphysis. There is
saucerization (scalloping) of the inner cortex. (B) Photomicrograph demonstrates a lobular lesion composed of mature cartilaginous tissue.
Radiographic Features
  • Plain radiographs show a sharply circumscribed radiolucent lesion located centrally in the medullary canal (Fig. 23-10A).
Histologic Features
  • Grossly, enchondromas are lobular lesions with a bluish color.
  • Histologically, lobules of hyaline cartilage with varying cellularity are seen and are recognized by their blue matrix (see Fig. 23-10B). The chondrocytes are located in rounded spaces called lacunae.
Natural History and Treatment
  • Malignant transformation of enchondromas occurs infrequently (less than 1%), and is rare before skeletal maturity.
  • Patients experiencing pain in a
    previously asymptomatic lesion without evidence of a pathologic
    fracture should be evaluated for this possibility.
  • Asymptomatic solitary enchondromas do not require any treatment other than a periodic follow-up evaluation.
  • Symptomatic or large lesions in the short
    tubular bones of the hand without a pathologic fracture can be managed
    with curettage and bone grafting.
  • If a pathologic fracture occurs through
    an enchondroma, the fracture should be allowed to heal prior to
    curettage and bone grafting.
  • Recurrence after curettage and bone grafting is rare.
  • P.261
  • Incisional biopsy usually is contraindicated.
    • □ Pathologists may have difficulty
      distinguishing an active enchondroma (most pediatric patients have
      active lesions) from a low-grade chondrosarcoma.
    • □ An incisional biopsy alters the histologic and radiographic status of the lesion and may make subsequent evaluation difficult.
Multiple Enchondromatosis
  • Also known as Ollier disease, it is an inherited condition with widespread enchondromas.
  • It is much less common than solitary enchondroma.
  • Patients with Ollier disease have an increased risk of developing secondary chondrosarcoma later in life.
  • Multiple enchondromatosis with vascular anomalies of soft tissues is known as Maffucci syndrome (see “Vascular Tumors”
    later in the chapter). Patients with this disorder have an even greater
    risk of developing malignant cartilage tumors than patients with Ollier
    disease; importantly, they also have a greater risk of developing
    carcinoma of an internal organ.
Nonossifying Fibroma
  • Nonossifying fibroma (NOF), fibrous cortical defect, metaphyseal fibrous defect, and fibroma all refer to the same histopathologic process in bone.
  • Fibrous cortical defects are small
    asymptomatic lesions that occur in 30% of the population during the
    first and second decades of life.
  • NOF refers to a lesion that enlarges and encroaches on the medullary bone.
  • Benign proliferation of fibroblast-like mesenchymal tissue that is more likely a hamartomatous process than a true neoplasm
  • Most common in the long bones, especially the distal femur and the tibia
  • Asymptomatic lesion that is often found
    only when a radiograph is taken for another reason or when the patient
    has a pathologic fracture
Figure 23-11 Nonossifying fibroma. (A)
Anteroposterior and lateral radiographs of the distal tibia show a
cortically based, lytic lesion with well-defined margins. Note the
typical scalloped appearance. Involvement greater than 50% of the
diameter of the bone puts this lesion at risk for pathologic fracture. (B)
Photomicrograph (high power magnification) of the lesion demonstrates
foamy histiocytic cells and giant cells discerned within the
fibroinflammatory spindle cell stroma.
Radiographic Features
  • Plain radiographs show an eccentric,
    metaphyseal lesion, involving the medullary canal, with a loculated
    appearance and a radiodense rim (Fig. 23-11A).
  • NOFs range in size from 0.5 to 7 cm, with their long axes aligned with the long axis of the affected bone.
Histologic Features
  • Histologically, NOF consists of benign, spindle, fibroblastic cells arranged in a storiform pattern (see Fig. 23-11B).
  • Multinucleated giant cells are common, and foam cells containing lipid often can be seen.
  • Hemosiderin within the spindle cells and multinucleated giant cells are usual.
  • Typically, the lesion does not contain bone.

Natural History and Treatment
  • Fibrous cortical defects need no treatment, they heal spontaneously.
  • NOFs less than 50% of the diameter of the bone and that are asymptomatic and can be observed.
  • NOFs occupying more than 50% of the
    diameter of the bone, have an increased risk of developing pathologic
    fractures, and should be considered for curettage and bone grafting.
  • Patients who present with pathologic fractures can usually be managed nonoperatively.
Fibrous Dysplasia
  • A nonneoplastic condition of aberrant bone development.
  • Produces a variety of complaints and physical findings.
  • 85% of cases are a single skeletal lesion (monostotic fibrous dysplasia).
  • 15% have numerous lesions (polyostotic fibrous dysplasia).
  • The most common locations for monostotic fibrous dysplasia are ribs, proximal femur, tibia, and the base of the skull.
  • The patient with monostotic fibrous
    dysplasia usually presents without significant symptoms, and the lesion
    is usually discovered incidentally on radiographs obtained for other
  • Occasionally, a child presents with a pathologic fracture or angular deformity (Fig. 23-12A).
Radiographic Features
  • Fibrous dysplasia is a medullary process usually involving the full width of the bone.
  • Plain radiographs show a radiolucent
    lesion with slight expansion and thinning of the cortex, and partial
    loss of trabecular pattern in the cancellous bone, which gives the
    characteristic ground-glass appearance (see Fig. 23-12A).
    • □ Cystic areas can also be seen within the abnormal bone.
    • □ There may be an angular deformity or bowing in the bone, especially when the lesion is large.
    • □ The lesions are usually diaphyseal, and the differential diagnosis may include other common diaphyseal lesions of bone.
  • On the bone scan, uptake within the lesion is usually intense.
Figure 23-12 Fibrous dysplasia. (A)
Anteroposterior radiograph of the pelvis shows subtle ground-glass
density of the left femoral neck and proximal diaphysis. The cortex
blends imperceptibly with the medullary canal. A pathologic fracture is
seen at the base of the femoral neck. (B)
Photomicrograph of the lesion demonstrates irregular woven bone
trabeculae (so-called Chinese letters) in a background of bland
fibroblastic stroma. Note absence of osteoblastic rimming.
Histologic Features
  • Histologically, fibrous dysplasia (both
    the monostotic and polyostotic variants) is composed of trabeculae of
    immature, woven bone within a background stroma of collagen-rich tissue
    (see Fig. 23-12B).
  • The osteoid and bone appear to arise in a haphazard fashion from the fibrous stroma.
  • The trabeculae often obtain a variety of shapes (C’s and O’s) and are sometimes referred to as alphabet soup or Chinese letters.
  • Monostotic fibrous dysplasia usually does not require any treatment other than observation.
  • Surgical treatment may be required for
    lesions that are very large or enlarging, in a high-stress location
    (i.e., proximal femur), or have become symptomatic.
  • Intralesional extended curettage is
    performed for eradication of the lesion; curettage often results in
    healing with dysplastic, mechanically deficient bone, similar to the
    pattern of fracture healing in fibrous dysplasia.
  • Therefore, the goals of surgical
    treatment, when indicated, are clearly different from other benign
    active or aggressive lesions.

    • □ Rather than resect the lesional tissue, the goals are to stabilize the bone, prevent or correct deformity, and relieve pain.
    • □ Prophylactic internal fixation may be required depending on the size and location of the lesion.
Albright Syndrome
  • Polyostotic fibrous dysplasia may occur as a part of a condition known as McCune-Albright syndrome which is characterized by a classic triad of polyostotic fibrous dysplasia, café-au-lait skin lesions, and precocious puberty.
  • Activating missense mutations of the guanine nucleotide-binding protein gene (GNAS), encoding the α-sub-unit of the stimulatory G protein, have been identified in patients with this syndrome.
Unicameral Bone Cyst (Simple Bone Cyst)
  • Tumor-like cystic lesion of unknown cause, attributed to a local disturbance of bone growth
  • Arises on the metaphyseal side of the growth plate and is displaced from the physis with skeletal growth
  • The most common locations are the proximal humerus and femur, accounting for 90% of lesions, followed by calcaneus
  • Commonly are asymptomatic, and often come to attention only after pathologic fracture has occurred
Radiographic and Histologic Features
See Table 23-5 and Figure 23-13A.


Aneurysmal Bone Cyst

Unicameral Bone Cyst


Gross (macroscopic)

Blood-filled sponge with thin periosteal membrane

Cystic cavity usually filled with yellowish fluid

Histologic (microscopic)

Cavernous blood-filled spaces lacking endothelial cell lining

Fibrous septa forming the walls contain woven bone trabeculae, giant cells, and hemosiderin-laden macrophages

A cyst lining consisting of a single layer of mesothelial cells with underlying connective tissue or bone


Plain radiographs

Metaphysis of long bones

Eccentric or involve entire width of bone

Expansile, lytic lesion circumscribed with a thinned, but intact bony cortex

Internal septations within the lesion

Metaphysis of long bones

Centrally located

Well-circumscribed, lucent lesion with sclerotic margins

Magnetic resonance imaging

Internal septations and multiple fluid-fluid levels

Marked bony expansion

Fluid-fluid levels, only if hemorrhage has occurred

Minimal bony expansion

Natural History and Treatment
  • Tend to enlarge with skeletal growth
  • Enters a latent phase after skeletal maturity, ceases growing, is resorbed, and is replaced by normal bone
  • Some unicameral bone cysts remain small
    and do not present a significant risk of a pathologic fracture.
    Observation and activity restriction may be all that is necessary for
    these lesions.
  • In most cases, a pathologic fracture should be treated nonoperatively until it heals.
  • Healing of the fracture usually does not
    result in healing of the bone cyst (less than 10% of cysts heal with
    pathologic fracture).
  • Surgical treatment options include
    curettage and bone grafting, and fluoroscopically guided percutaneous
    corticosteroid injection, which are both associated with high
    persistence and recurrence rates, and some morbidity.
  • Newer techniques include injection with
    autologous bone marrow or demineralized bone matrix, and percutaneous
    intramedullary decompression, curettage, and grafting using bone graft
    substitutes (calcium sulfate pellets) (see Fig. 23-13B and C).
    • □ The short-term results of these techniques are very promising, with high healing and low complication and recurrence rates.
Aneurysmal Bone Cyst (ABC)
  • Vascular lesions consisting of widely dilated vascular channels that are not lined by identifiable endothelium.
  • 1% to 2% of all benign bone lesions.
  • Etiology is not known.
  • Occur in association with other benign (i.e., giant cell tumor, chondroblastoma, osteoblastoma) and malignant


    (i.e., osteosarcoma) processes as “secondary ABCs” in up to 30% of cases.

  • More than 50% of ABCs arise in large tubular bones, and almost 30% occur in the spine.
  • Mild, dull pain; only rarely is there a clinically apparent pathologic fracture.
Figure 23-13 Unicameral bone cyst. (A) Lateral radiograph of the foot depicts a lytic lesion in calcaneus with well-defined margins. (B)
This lesion was treated by percutaneous intramedullary decompression,
biopsy, curettage, and grafting with calcium sulfate pellets. (C) Postoperative 1-year follow-up radiograph shows complete healing of the lesion.
Radiographic and Histologic Features
See Table 23-5 and Figure 23-14.
Natural History and Treatment
  • ABCs are benign by histology, but can be locally aggressive (Box 23-5).
  • They should undergo biopsy to establish the diagnosis, and then be treated surgically.
  • The usual treatment for ABCs is extended curettage and bone grafting.
  • ABCs in expendable bones, such as fibula, ribs, distal ulna, metacarpal, and metatarsal bones, may be treated by en bloc resection.
    • □ Resection is also appropriate for recurrent aggressive lesions.
  • An ABC of the spine can present a challenging problem.
    • □ The lesion usually involves the posterior elements, but can also invade into vertebral body.
    • □ Surgery is recommended for most patients as the initial means of treatment.
    • □ Radiotherapy is contraindicated.
  • More recently, selective arterial
    embolization has been used in conjunction with surgery or as a curative
    procedure alone for some pelvic and spinal lesions.

Figure 23-14 Aneurysmal bone cyst. (A)
Lateral radiograph of the knee shows a large lytic lesion expanding the
distal femoral metaphysis. Note the trabeculated, nonossified matrix. (B)
Photomicrograph of this lesion demonstrates salient features including
scattered erythrocytes within the cyst cavity, lack of an endothelial
lining, and an occasional giant cell in the underlying stroma.
Ewing Sarcoma
  • Second most common primary malignant bone tumor in children
  • Ewing sarcoma (EWS) is closely related to
    primitive neuroectodermal tumor (PNET); both these tumors are thought
    to arise from the neural crest and at least 90% have a characteristic
    chromosomal translocation [t(11:22)(q24:q12)], which leads to a novel
    fusion protein called EWS-FLI1 (Table 23-6).
  • The femur is the most common site of origin, followed by the pelvis and humerus.
  • Pain and local swelling are the most common presenting symptoms.
  • EWS may present with fever and an elevated sedimentation rate and may mimic bacterial osteomyelitis.
  • Approximately 5% of patients with EWS present with pulmonary metastasis.



Ewing sarcoma/primitive neuroectodermal tumors

t(11;22); t(21;22)

Alveolar rhabdomyosarcoma

t(2;13); t(1;13)

Synovial sarcoma


Myxoid liposarcoma


Radiographic Features
  • Plain radiographs demonstrate diffuse
    destruction of bone, usually occurring in the diaphyseal regions of
    long bones or in flat bones of the axial skeleton (Fig. 23-15A).
    • □ The lesion usually is associated with a periosteal reaction (Fig. 23-2), which has an “onion-skin” or sunburst appearance, and a large soft tissue mass.
  • On bone scan, EWS shows a very increased uptake; it may be multicentric.
  • MRI is essential for definitive
    demonstration of extraosseous soft tissue mass, determining
    relationship of the tumor to surrounding structures, and determining
    medullary canal involvement, both of which are usually more extensive
    than what was expected from the plain radiographs (see Fig. 23-15B and C).
Histologic Features
  • Histologically, EWS consists of small,
    uniform-sized cells characterized by an almost clear cytoplasm and
    nuclei that are round and slightly hyperchromatic (see Fig. 23-15D).
    • □ Necrotic areas usually are seen.
    • □ There are glycogen granules in the
      cytoplasm, and these produce the positive periodic acid-Schiff (PAS)
      stain on routine histology.
  • Increasingly, genetic analysis is being
    done for EWS to identify the 11:22 translocation as a means of
    establishing the diagnosis.

Figure 23-15 Ewing sarcoma. (A)
Anteroposterior radiograph of the distal fibula reveals an irregular,
hazy patterned, periosteal new bone formation with fine spiculations
and a Codman triangle at the superior edge (arrow).
This aggressive pattern of new bone formation is associated with
enlargement of the soft tissues and obliteration of the fat planes due
to a soft tissue mass. The underlying bone has a permeative pattern of
bone destruction. (B) Axial T2-weighted
magnetic resonance image shows abnormal, hyperintense signal in the
marrow of the fibula. Patches of hypointense signal are scattered
throughout the cortex as well. Spicules of new bone formation are well
seen. A large, fairly homogeneous, soft tissue mass invades the lateral
compartment. (C) Coronal T1-weighted,
fat-saturated image with contrast enhancement shows (abnormally)
enhancement extending from the distal metaphysis to the mid-fibula (arrow).
An enhancing soft tissue mass encompasses the fibula and extends up
into the proximal soft tissues above the marrow abnormality. (D)
Photomicrograph of the lesion demonstrates primitive, small, and
uniform malignant cells with inconspicuous cytoplasm. Darker staining
cells are pyknotic.

  • Multiagent chemotherapy has made a
    significant difference in the prognosis for patients with EWS,
    improving the 5-year survival rate from 5% to 10% to over 70%.
  • Current treatment principles of EWS are summarized in Box 23-3.
  • Treatment of EWS is a combination of chemotherapy and either surgery or irradiation.
Hemangiomas are true
neoplastic lesions with endothelial hyperplasia. They are the most
common benign soft tissue tumors of childhood, occurring in 4% to 10%
of all children. They infrequently are present at birth but grow
rapidly during the first 2 to 3 weeks of life. Hemangiomas may be
located in the superficial or deep dermis, subcutaneous tissue,
musculature, bone, or viscera. Head and neck are the most commonly
involved sites.
The second category of vascular anomalies is vascular malformations,
which are congenital lesions with normal endothelial turnover. They are
subclassified by the predominant vessel found in the lesion (i.e.,
venous, arterial, capillary, lymphatic, mixed) and by the blood flow
within the lesion (high vs. low flow). Vascular malformations are not
seen as commonly as hemangiomas. Many of the common vascular
malformations are present at birth, however some may manifest in
adolescence or adulthood. The majority of these lesions involve the
skin and subcutaneous tissue, but deep or extensive involvement of
structures such as muscle, joint, bone, abdominal viscera, and central
nervous system is not uncommon. The most commonly affected sites are
head and neck.
Figure 23-16 Vascular malformation: lymphangioma. (A)
Axial T2-weighted magnetic resonance image of the distal thigh shows a
high-signal intensity mass similar to fluid. No vessels or septations
are seen within the mass. (B) On sagittal T2-weighted image, a vitamin E capsule (C) is used to mark the site of the palpable mass. Note the high signal of this fluid-filled mass (M). A small suprapatellar effusion, just inferior to the mass, has the same signal intensity.
MRI is an excellent imaging modality for confirming the
nature of vascular anomalies and defining their relationship to
adjacent structures (Fig. 23-16). Ultrasound or color Doppler may also be used.
  • In the absence of intervention, partial
    or complete involution of hemangiomas usually occurs, and correction of
    cosmetic defects typically follows.
  • When intervention for a rapidly expanding
    hemangioma is necessary, the first line of treatment is intralesional
    or systemic corticosteroids.
  • Occasionally, when surgical resection is
    indicated for larger, deeper lesions that threaten normal function,
    staged excisions may be considered.
Venous Malformations
  • Compression stockings to prevent
    progressive venous dilation, pain, ulceration, and bleeding are the
    mainstay of treatment, and low-dose aspirin may also be used to
    minimize thrombophlebitis.
  • P.268
  • When the patient does not receive
    adequate benefit from compression stockings, laser surgery,
    sclerotherapy (i.e., 100% ethanol), or surgical resection are all
    widely accepted treatment methods.
  • Surgical intervention may be required for
    deep venous malformations involving muscle or bone, which have led to
    pain, functional impairment or pathologic fracture.
  • Epiphysiodesis may be performed in patients with extensive venous malformations that have resulted in skeletal overgrowth.
Arteriovenous Malformations
  • AVMs can prove deceptively problematic and even dangerous to treat.
  • Most experts agree that conservative treatment is preferred in the absence of significant symptoms.
  • Deep AVMs may cause significant muscle or bone changes and will necessitate surgical debulking or epiphysiodesis.
  • When surgery is required, angiographic
    studies followed by selective embolization is usually done 24 or 72
    hours before resection.
  • Embolization or ligation of feeding
    arteries without surgical resection is contraindicated because
    occlusion of the major feeding arteries usually results in rapid
    recruitment and dilation of previously microscopic collateral blood
Neurolemmoma and neurofibroma are the most common benign
tumors of peripheral nerves. Both arise from benign proliferation of
periaxonal Schwann cells that embryologically arise from the neural
Figure 23-17 Histopathology of benign peripheral nerve sheath tumors. A: Neurolemmoma. This tumor demonstrates a classic palisading of Schwann cells (Verocay bodies) within a spindlecell background. (B)
Neurofibroma. The lesion is composed of fascicles of Schwann cells and
fibroblasts within an edematous and mildly inflamed background stroma,
imparting a histologic appearance that has been compared to shredded
Neurolemmomas, also known as schwannomas,
can be seen in patients of all ages, but they are most often
encountered in early adulthood. They have a predilection for the head,
neck, and flexor surfaces of the extremities (i.e., peroneal, ulnar
nerves). The patient usually presents with a painless, slow-growing,
solitary mass in the subcutaneous tissue. Although they arise from the
nerve sheath, nerve dysfunction is uncommon, and is seen only when the
nerve is compressed between the tumor and an adjacent rigid structure.
A positive Tinel sign with percussion over the mass is not uncommon.
Neurolemmomas rarely are associated with neurofibromatosis.
Neurofibromas, like neurolemmomas, usually present
during young adulthood. They may present as solitary lesions or as
multiple lesions in association with neurofibromatosis, but the
majority (90%) are solitary. Like neurolemmomas, they grow slowly as a
painless mass in the skin, subcutaneous tissue, or the distribution of
a peripheral nerve. Unlike neurolemmomas, they tend to be intimately
associated with the nerve fibers (Fig. 23-17).
Natural History and Treatment
The risk of malignant transformation of neurolemmomas or
solitary neurofibromas is exceedingly rare. In contrast, malignant
transformation of neurofibromas in the face of neurofibromatosis is
well documented; this risk has been reported in about 2% of cases.
Therefore, patients and parents should be aware of the clinical
symptoms leading to suspicion of malignant transformation, such as
enlargement of a neurofibroma and pain. If sarcomatous degeneration
occurs, the prognosis for long-term survival is poor.
Neurofibrosarcomas can also rarely arise de novo.

  • Treatment of neurolemmomas consists of marginal surgical excision.
  • Overlying nerve fibers can usually easily be mobilized and preserved as the lesion is marginally shelled out.
  • Neurolemmoma usually does not recur following marginal excision.
  • Marginal surgical excision is recommended for symptomatic solitary neurofibromas involving a peripheral nerve.
  • Those arising from a major nerve can be resected, but they should be approached cautiously.
  • Most common soft tissue tumor in children
  • 5% of all pediatric cancers
  • Arises from the same embryonal mesenchyme that is destined to give rise to striated skeletal muscle.
  • Peak incidence is in the 1- to 5-year age group.
  • There are four histologic patterns: embryonal, botryoidtype, alveolar, and pleomorphic.
    • □ Embryonal and alveolar types are common.
    • □ Embryonal tumors are most often found in the head and neck or the genitourinary tract.
    • □ Alveolar rhabdomyosarcomas are more commonly found in the extremities and trunk.
  • Extremity lesions usually present as a painless mass, while paravertebral tumors may cause back pain.
  • Characteristic chromosomal abnormalities have been identified in the alveolar rhabdomyosarcoma (Table 23-6).
Figure 23-18 Alveolar rhabdomyosarcoma. (A)
Axial T1-weighted magnetic resonance image through the humerus shows a
slightly hyperintense mass replacing the triceps muscles of the arm.
The neurovascular bundle (arrowheads) is contiguous with the anterior medial edge of the mass. (B) After contrast administration, there is heterogeneous enhancement of the mass. (C)
Photomicrograph of the lesion demonstrates undifferentiated small blue
cells lining fibrovascular septae with central discohesion, imparting
an alveolar appearance.
Radiographic Features
  • MRI shows a heterogeneous mass, indicating the presence of blood or necrosis.
  • Tumor invasion and extent are variable (Fig. 23-18A and B).
  • P.270
  • MRI provides important information about tumor extent which is necessary for treatment planning.
Histologic Features
  • Embryonal rhabdomyosarcoma consists of poorly differentiated rhabdomyoblasts with a limited collagen matrix.
    • □ The rhabdomyoblasts are small,
      round-to-oval cells with dark-staining nuclei and limited amounts of
      eosinophilic cytoplasm (see Fig. 23-18C).
  • Alveolar rhabdomyosarcoma is composed of
    poorly differentiated small, round-to-oval tumor cells that show
    central loss of cellular cohesion and formation of irregular alveolar
    • □ The individual cellular aggregates are separated and surrounded by irregularly shaped fibrous trabeculae.
Natural History and Treatment
  • Prognostic variables for
    rhabdomyosarcomas include histologic subtype, size of the tumor, site
    of the tumor, and age of the patient.
  • Alveolar subtype, larger tumors,
    extremity location, and patients older than 10 years of age are more
    often associated with a poorer prognosis.
    • □ Alveolar rhabdomyosarcoma, like the other subtypes, is treated with a combination of chemotherapy and surgery.
    • □ Irradiation can be used if total surgical resection cannot be achieved without excessive morbidity.
    • □ Total resection of the tumor with wide
      surgical margins is recommended, and preoperative chemotherapy often
      makes total resection of an extremity lesion possible.
  • Lymph node biopsy should be considered if the patient has any suggestion of lymph node involvement.
  • Postoperative irradiation may be used
    when the surgical margins are positive for tumor or there is poor
    necrosis of excised tumor from chemotherapy.
  • The overall survival for a patient with extremity rhabdomyosarcoma is approximately 65%.
The authors thank Ms. Julia Lou for her research assistance during the writing of this chapter.
CM, Dehner LP, O’Shea PA. Pediatric soft tissue tumors: a clinical,
pathological, and therapeutic approach. Baltimore: Williams &
Wilkins, 1997.
Copley L, Dormans JP. Benign pediatric bone tumors. Pediatr Clin North Am 1996;43:949.
JP, Flynn J. Pathologic fractures associated with tumors and unique
conditions of the musculoskeletal system. In: Rockwood and Wilkins
fractures in children, 5th ed., Beatty JH and Kasser JR, eds., 2001,
pp. 139-240.
Enneking WF. Musculoskeletal tumor surgery. New York: Churchill Livingstone, 1983.
A, Remagen W. Differential diagnosis of tumors and tumor-like lesions
of bones and joints. Philadelphia: Lippincott-Raven, 1998.
Himelstein BP, Dormans JP. Malignant bone tumors of childhood. Pediatr Clin North Am 1996;43:967.
JE, Ragsdale BD, Sweet DE. Radiologic and pathologic analysis of
solitary bone lesions. Part I: internal margins. Radiol Clin North Am
BD, Madewell JE, Sweet DE. Radiologic and pathologic analysis of
solitary bone lesions. Part II: periosteal reactions. Radiol Clin North
Am 1981;19:749.
Simon MA, Biermann JS. Biopsy of bone and soft tissue lesions. J Bone Joint Surg (Am) 1993;75:616.

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