Limb-salvage procedures (i.e., local excision) have replaced amputation as the primary treatment of soft tissue sarcomas; however, despite the efficacy of limb-salvage procedures in obtaining local control, pulmonary metastases remain a significant problem and occur in 30% to 50% of patients.

MALIGNANT FIBROUS HISTIOCYTOMA

Malignant fibrous histiocytoma is seen in adults and primarily metastasizes to the lungs.

Diagnostic Studies. Although the extent of soft tissue involvement and the tumor’s relationship to the major neurovascular structures can be estimated by CT, MRI is more precise and differentiates normal from neoplastic tissue and shows edema.

Treatment/Prognosis. Treatment with a wide surgical margin of greater than 1 cm is usually adequate. In areas where a 1-cm margin is not possible, irradiation either preoperatively, intraoperatively, or postoperatively should be considered. CT should be obtained to determine if chest metastases are present; if they are, then chemotherapy should be considered, although chemotherapy is not of proven benefit in most soft tissue sarcomas. Amputation is reserved for multiple recurrences in which the tumor bed or previous surgical field cannot be completely resected.

FIBROSARCOMA OF SOFT TISSUE

The diagnosis of fibrosarcoma is rare (see Plate 6-25). Low-grade stage I fibrosarcoma is often difficult to distinguish from its benign but aggressive counterpart of fibromatosis (see Plate 6-23).

Diagnostic Studies. Radiographs show a lesion with a discrete margin. Histologic characteristics are marked cellular atypia and abundant collagen in a herringbone pattern. A low-grade fibrosarcoma can be confused with aggressive juvenile fibromatosis, a diagnostic difficulty that affects treatment choices.

SYNOVIAL SARCOMA

Synovial sarcoma is a tumor of children and young adults and is derived from the synovial tissues found along fascial planes, in periarticular structures, and, rarely, in joints (see Plate 6-26). An enlarging, painful, juxta-articular mass is the primary clinical manifestation. Occurring most frequently as a stage IIB lesion in the lower limbs, it may also appear as a stage I tumor, in which case it may be confused with a ganglion.

Diagnostic Studies. The lesion is often adjacent to major neurovascular structures and adjacent to, but not usually within, joints despite the term synovial. Accurate localization is best provided by MRI.

Histologic examination reveals a biphasic pattern, with intermixed areas of epithelial, glandular synovial-like cells and spindle-shaped cells. Depending on the relative prominence of these two components, synovial sarcomas are classified as biphasic, monophasic, and poorly differentiated.

Treatment/Prognosis. Despite adequate local control, the incidence of both regional and pulmonary metastases is high, and the long-term prognosis for patients with synovial sarcoma is poor. Synovial sarcoma not only metastasizes to the lungs but also has about a 10% incidence of lymph node metastasis, which has led some to recommend sentinel lymph node biopsy as part of the staging. Synovial sarcoma is sensitive to chemotherapy, with a response in 50% of patients.