Bizarre parosteal osteochondromatous proliferation (BPOP) is a rare benign
lesion predominantly involving the small bones of the hands and feet. Malig
nant transformation in BPOP has not been documented in the English literatu
re. This report presents the coexistence of fibrosarcoma with BPOP in the r
ight distal fibula of an 18-year-old woman.