Benign Parosteal Osteochondromatous Proliferation of the Hand Originally Diagnosed as Osteochondroma: A Report of Two Cases and Review

Bizarre parosteal osteochondromatous proliferation (BPOP) is a rare cartilaginous neoplasm that often presents in the long bones of the hands and feet. BPOP is a benign but locally aggressive fibro-osseous mass that has striking clinical, radiographic, and histologic similarities with osteochondroma. Differentiating between the two lesions is important as BPOP often requires more extensive surgical resection and has a higher recurrence rate compared to osteochondroma. This report presents two cases of BPOP where initial clinical diagnosis of osteochondroma was made even after appropriate imaging and histologic samples were evaluated. This report reviews clinical, radiographic, and histologic characteristics that can differentiate between the two lesions.