CONVENTIONAL AND DEDIFFERENTIATED PAROSTEAL OSTEOSARCOMA - DIAGNOSIS,TREATMENT, AND OUTCOME

BACKGROUND. Dedifferentiated parosteal osteosarcoma (dd-POS) designate s high grade transformation of conventional low grade parosteal osteos arcoma (c-POS). The paradigm of preoperative diagnosis, neoadjuvant ch emotherapy, and wide local excision has not been adequately evaluated for dd-POS, as it has been far conventional high grade intramedullary osteosarcoma. METHODS. A retrospective review was conducted of 28 pati ents treated at the authors' institution between January 1980 and Dece mber 1992 for an osteosarcoma arising on the surface of the bone diagn osed as either c-POS or dd-POS. The clinicopathologic features, diagno sis, treatment, and patient outcome were analyzed. RESULTS. A dediffer entiated component was identified in 12 of 28 tumors (43%). Neither th e presence of radiolucencies (77% in c-POS and 100% in dd-POS, P = 0.0 6) nor medullary invasion (42% in c-POS and 50% in dd-POS, P = 0.28) d istinguished dd-POS from c-POS. However, all patients who presented wi th focal hypervascularity on an arteriogram defined the high grade com ponent of dd-POS that was confirmed by selective needle biopsy. This d iffered significantly (P = 0.00003) from c-POS. None of the patients w ith c-POS died of the disease (median survival duration, 77 months; ra nge, 16-152 months). Six patients (35%) developed a local recurrence, but five were treated successfully with further surgery. In the dd-POS group, 7 of the 12 patients died of the disease. Ten patients with dd -POS received preoperative chemotherapy (IA cis-diamminedichloroplatin um, IV doxorubicin), and a good response (>90% necrosis of high grade component) was observed in four. Among patients whose disease was loca lized, continuous disease free survival was prolonged significantly (P = 0.03) in patients with a good response (median, 75 months) compared with those who responded pearly (median, 13 months). Five patients re mained continuously disease free (median, 66 months; range, 29-95 mont hs). CONCLUSIONS. Wide surgical excision alone is adequate treatment f or patients with c-POS. Recognition of dedifferentiated areas with ang iography and percutaneous biopsy of hypervascular areas should prompt the administration of chemotherapy and wide local excision to optimize patient outcome. (C) 1996 American Cancer Society.