Bizarre Parosteal Osteochondromatous Proliferation-Like Lesion Originating in Soft Tissue: Report of a Case

Many tumors are unique to the organs from which they arise. Over the last 20 years, however, most tumors that were thought to be primary in soft tissues (derived from the primitive mesenchyme) and thought not to have counterparts in bone, were found to, in fact, rarely arise as unique lesions from bone. Some examples include synovial sarcoma, rhabdomyosarcoma and leiomyosarcoma, to name but three. We now have begun to see the reverse with lesions that were initially thought to be unique to bone arising in soft tissue. While this has been well reported with osteosarcoma and Ewing’s sarcoma, it has never been reported with Bizarre Parosteal Osteochondromatous Proliferation (BPOP), also known as Nora’s lesion. This study explores the first reported case of a soft tissue lesion, with clinical, radiological and histopathological characteristics of BPOP.