Para-articular osteochondroma: Role of diagnostic imaging

Para-articular osteochondroma (PAOC) is a subtype of extra-skeletal chondroma. This is a rare slow growing benign soft tissue tumour which arises from the adjacent joint and without continuity with the bone. The knee joint is the most frequent site of involvement, particularly at the infra-patellar fossa. We report two cases of para-articular osteochondroma of the knee joint. Based on the imaging features, the diagnosis of para-articular osteochondroma was made and confirmed by histopathological examination. Meticulous clinical-pathologic and imaging evaluation allows recognition of this entity. The imaging findings and the differential diagnoses are highlighted.