Parosteal osteogenic sarcoma.

A clinicopathologic study of 79 patients with parosteal osteogenic sarcoma revealed that more females than males were affected and that most of the patients were in the second to the fourth decades of life. Sixty-eight percent of the patients had involvement of the posterior aspect of the lower femoral shaft. The roentgenogram characteristically showed a large, dense lobulated mass attached by a broad base to the underlying bone but with no involvement of bone itself. Microscopically, the tumor presented as well-formed bands of osteoid within a hypocellular spindle cell stroma. Seven of the lesions had foci of high-grade osteogenic sarcoma within an otherwise typical parosteal osteogenic sarcoma. Six of the 79 lesions showed involvement of the medullary cavity at surgery. Thirty-one patients had excision as their initial treatment; four of the 31 required nv further therapy. Ten patients had resection initially; three of the ten had recurrence. Only four of 27 patients who underwent amputation initially developed pulmonary metastasis. The presence of histologically "active" tumor and medullary involvement seemed to affect the prognosis adversely. Our data indicate that complete radical removal of the tumor is the treatment of choice, with resection when feasible and amputation when necessary.