The Many Faces of Osteosarcoma

Abstract Introduction Primary Intramedullary Osteosarcoma

Surface Osteosarcoma Extraskeletal Osteosarcoma Secondary Osteosarcoma

Conclusions Source Information References

Extraskeletal Osteosarcoma

Extraskeletal or soft-tissue osteosarcoma is rare, representing approximately 1.2% of all soft-tissue sarcomas and 4% of all osteosarcomas (1,2,3,90,91,92,93,94). The peak prevalence occurs in patients in the 6th decade of life, and men are slightly more frequently affected. Symptoms often include a slowly growing painful mass, and a history of trauma is not infrequent (12% of cases) (92). Common sites of involvement are the deep soft tissues of the thigh (47% of cases), upper extremity (20%), and retroperitoneum (17%) (90,91,92,93,94).

Extraskeletal osteosarcomas are usually large (average, 9 cm in diameter) with variable amounts of neoplastic osteoid and bone (91). Other histologic components, including cartilage, fibrosarcoma, malignant fibrous histiocytoma, and malignant peripheral nerve sheath tumor, are also frequently seen within extraskeletal osteosarcoma (90).

Radiologic studies show large soft-tissue masses with focal to massive areas of mineralization and a lack of osseous involvement (Figure 17) (94,95). Nonmineralized areas have muscle attenuation values on CT scans, nonspecific intermediate signal intensity on T1-weighted images, and high signal intensity on T2-weighted MR images and show contrast enhancement (95). A pseudocapsule may also be apparent. Scintigraphy often reveals increased radionuclide uptake in both primary and metastatic foci.

Treatment consists of amputation or wide surgical resection with neoadjuvant chemotherapy or radiation therapy. Tumor size is the most important prognostic factor, with patients with lesions larger than 5 cm having a worse outcome (90,91,92,93,94). Despite aggressive therapy, overall prognosis is poor, with patient death occurring in at least 60% of cases (90,91,92). Metastases are frequent and most commonly involve the lung, regional lymph nodes, and bone.

Abstract Introduction Primary Intramedullary Osteosarcoma

Surface Osteosarcoma Extraskeletal Osteosarcoma Secondary Osteosarcoma

Conclusions Source Information References