Soft-Tissue Tumors

By admin Last updated Mar 5, 2024

Ovid: 5-Minute Orthopaedic Consult

Editors: Frassica, Frank J.; Sponseller, Paul D.; Wilckens, John H.

Title: 5-Minute Orthopaedic Consult, 2nd Edition

> Table of Contents > Soft-Tissue Tumors

Soft-Tissue Tumors

Constantine A. Demetracopoulos BS

Frank J. Frassica MD

Basics

Description

Soft-tissue tumors may occur in any area of the skeleton and in individuals of any age.
They may comprise fibrous tissue or tissue originating from muscle, fat, vessels, or nerves.
Reactive lesions also cause soft-tissue tumors.
Benign tumors far outnumber malignant ones.
Differentiating the malignant from the benign can be difficult.
Staging: The Musculoskeletal Tumor Society (called the “Enneking” system) (1,2) classifies benign and malignant tumors:
- Benign lesions:
  - Stage 1: Inactive
  - Stage 2: Active
  - Stage 3: Aggressive
- Malignant tumors:
  - Stage I: Low grade
  - Stage II: High grade
  - Stage III: Metastatic

Epidemiology (3)

Only 15% of sarcomas occur in children.
>40% of sarcomas occur in patients >55 years old.
Although soft-tissue tumors may occur at any age, types may vary.
In childhood, the most common types include:
- Popliteal cyst
- Ganglion of wrist or ankle
- Neuroblastoma
- Neuroectodermal tumor
- Rhabdomyosarcoma

Incidence

Soft-tissue tumors in the aggregate are common.
Although the ratio of benign to malignant types is 100:1 (3), vigilance must be maintained to avoid missing malignant tumors.

Prevalence

No difference in gender risk is noted overall, but sarcomas are more common in males.

Risk Factors

Genetics

Most soft-tissue tumors are not inherited.
A notable exception is NF, which is
associated with multiple soft-tissue tumors and is inherited in an
autosomal-dominant manner.
Genetic abnormalities (4):
- Clear cell carcinoma: t(12;22)(q13;a12)
- Extraskeletal myxoid chondrosarcoma: t(9;22)(q22;q12)
- Synovial sarcoma: t(x;18)(p11;q11)
- Alveolar rhabdomyosarcoma: t(2;13)(q35;q14)
- Myxoid liposarcoma: t(12;16)(q13;p11)
- Alveolar soft part sarcoma: t(x;17)(p11;q25)

Etiology

The cause is largely unknown.
Myositis ossificans may occur with trauma.
Reactive granuloma may occur with implantation or retention of a foreign body.

Diagnosis

Signs and Symptoms

Presence of a mass
Possible loss of ROM of the adjacent joint
Usually painless or minimally painful
Absence of pain is not a reason to ignore the lesion.

Physical Exam

Inspect the lesion for size, depth, and mobility.
Obtain a history of recent growth.
Note consistency and fixation to surrounding structures.
It is more likely to be benign if it is small (<5 cm), soft, and superficial.
It is more likely to be malignant if it is large (>5 cm), hard, and deep.
Assess the effect on adjacent parts:
- Presence of limp
- Restricted joint motion
- Palpation of lymph nodes
- Examination of abdomen

Tests

Lab

Laboratory tests usually are not helpful, but screening tests may be helpful if a workup for malignant disease is undertaken.

Imaging

Radiography:
- Plain radiographs should be obtained
  first to look for phleboliths (indicating hemangioma) or rings and
  stipples (indicating chondroma).
- A lesion may appear radiodense or
  radiolucent if it is sandwiched between 2 tissues of lower density, as
  in deep lipomas in which the fat is contrasted between bone and muscle.
- Spotty calcifications occur in 20–30% of synovial sarcomas (3).
Ultrasound is used to look for homogeneity and size, but it has largely been replaced by MRI.
MRI (5):
- Superior in its ability to provide excellent soft-tissue definition and to characterize some tissues
- Many new signal combinations are available.
- The technique may need to be discussed with the radiologist beforehand.

Pathological Findings

Careful histologic evaluation is necessary, taking into account cell features, matrix production, and tissue organization.
Incorrect histologic diagnosis is not uncommon.

Differential Diagnosis

Intramedullary bone tumor with soft-tissue extension
Bone tumor arising from the surface of the bone

P.409

Treatment

General Measures

Observation:
- For inactive benign lesions (e.g., lipomas, ganglions) if they are not causing symptoms
If the nature of a lesion is not clear, it is important not to fall into the trap of complacency.
Initiate a diagnostic workup under the direction of an orthopaedist knowledgeable about the diagnoses.

Activity

Activity may increase the symptoms of some tumor types, such as a popliteal cyst, ganglion, or myositis ossificans.

Special Therapy

Physical Therapy

Physical therapy often is used postoperatively to restore function.

Medication

Chemotherapy is an effective adjuvant for a few of the malignant soft-tissue tumors (e.g., rhabdomyosarcoma and Ewing sarcoma).
Protocols vary from type to type, and
chemotherapy may be used before surgery in some types to shrink the
tumor and to make resection more feasible.

Surgery

The extent of surgery depends on the degree of malignancy.
- Benign tumors may be excised at their margins.
- Malignant tumors (sarcomas) should be excised with a layer of normal tissue around them.
  - ~95% of patients are treated with limb-sparing surgery.
Attachment to nerves or major vessels may prevent effective resection of malignant tumors.
If the lesion cannot be safely removed leaving a functional limb, amputation may be recommended.
Radiation therapy often is used to decrease the risk of local recurrence.

Follow-up

Prognosis

Depends on the following:
- Grade of malignancy
- Anatomic extent
- Treatment given
Superficial sarcomas (located above the
fascia) have an excellent prognosis (>80%), whereas deep, large,
high-grade lesions have the worst prognosis (only 50–60% long-term
survival) (3).

Complications

Infection
Recurrence
Misdiagnosis
Injury to local nerves and vessels

Patient Monitoring

Follow the patient at suitable intervals with physical examination or, in some cases, serial MRI scans.
After the resection of malignant tumors,
patients are followed at 3-month intervals for 2 years to look for
pulmonary metastases (CT scans) and then every 4–6 months for 5 more
years.
MRI scans are used to check for local recurrence 6 months after surgery and then once a year.

References

1. Enneking WF. A system of staging musculoskeletal neoplasms. Clin Orthop Relat Res 1986;204:9–24.

2. Frassica FJ, McCarthy EF, Bluemke DA. Soft-tissue masses: when and how to biopsy. Instr Course Lect 2000;49:437–442.

3. Weiss
SW, Goldblum JR. General considerations. In: Weiss SW, Goldblum JR,
eds. Enzinger and Weiss’s Soft Tissue Tumors, 4th ed. St. Louis: Mosby,
2001:1–19.

4. Lin
PP. Cellular and molecular biology of musculoskeletal tumors. In:
Menendez LR, ed. Orthopaedic Knowledge Update: Musculoskeletal Tumors.
Rosemont, IL: American Academy of Orthopaedic Surgeons, 2002:11–20.

5. Frassica
FJ, Khanna JA, McCarthy EF. The role of MR imaging in soft tissue tumor
evaluation: perspective of the orthopaedic oncologist and
musculoskeletal pathologist. Magn Reson Imaging Clin North Am 2000;8:915–927.

Miscellaneous

Codes

ICD9-CM

238.1 Neoplasm, connective tissue, uncertain behavior

Patient Teaching

The patient should be given a general understanding of the behavior of the tumor type.
Discuss the importance of follow-up and the risk of recurrence.

FAQ

Q: Should all patients with a soft-tissue mass have an MRI?

A:
If the clinician is positive of the behavior of the mass, such as a
subcutaneous lipoma or wrist ganglion, then an MRI is not necessary. In
contrast, if the clinician does not know the nature of the mass, an MRI
is necessary.

Q: Is a biopsy necessary for all soft-tissue masses?

A: If the clinician does not know the nature of the mass, a biopsy is necessary.