ABSTRACT
Purpose To investigate the clinicopathologic and imageologic characteristics of bizarre parosteal osteochondromatous proliferation (BPOP),osteochondroma and chondrosarcoma.Methods One case of BPOP on right humerus,one case of osteochondroma on left humerus,and one case of chondrosarcoma on right humerus were analyzed and compared on their clinical,pathologic and imaging manifestations and followup.Results The patients of BPOP and osteochondroma did not feel pain,but patient with chondrosarcoma felt severe pain.Microscopically,it was composed of different amounts cartilage,bone,and spindle cells with a poorly organized distribution.It appeared bizarre chondrocyte and characterized " blue bone".The mass was arising from the surface of the bone and the lesion was not cortical erosion and continuity with medullary cavity in the imaging findings.BPOP,osteochondroma and chondrosarcoma could be distinguished by the above characteristics.Conclusion BPOP is a rare and benign osteochondroma-like lesion,which may be confused with osteochondroma and chondrosarcoma.BPOP can be diagnosed definitely by combining histology with medical imageology.