Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

Featured on Channel NewsAsia

Soft-Tissue Tumors

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) 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
  • 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, 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:
    • 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 .
  • Ultrasound is used to look for homogeneity and size, but it has largely been replaced by MRI.
  • MRI :
    • 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
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).
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.
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.

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