Bizarre Parosteal Osteochondromatous Proliferation: A report of five cases

ABSTRACT

Bizarre parosteal osteochondromatous proliferation was first described in 1983, when Nora and his collegues reported 35 examples of a proliferative lesion involving bones of the hands and the feet. In 1993, Meneses reported 65 cases of this condition. A fourth of all the reported cases involved the long bones. It is important to identify the clinical, roentgenographic, and histologic characteristic to seperate it from other entities because it is a benign lesion with atypical microscopic features with a tendency to recur. Roentgenograms show a calcific mass attached to the underlying cortex having a broad base. Histologically, the lesion exhibites proliferative activity, irregular bony cartilaginous interfaces, and enlarged, bizarre, and binucleated chondrocytes. We reviewed the bone tumors, diagnosed in the KyungHee University Hospital, dated from 1984 to 1994. Five cases were revised to Nora's lesion, all of which were previously diagnosed as osteochondroma. The ages of the patients ranged from 12 to 57 years (median, 19 years), and all of them were males. Two cases involved the bones of hands and feet (metacarpal and talus), and 3 cases involved the long bones (humerus, fibula, and ulna). One lesion involving the humerus has a recurrence. No metastasis had been reported.