Intracapsular and para-articular chondroma adjacent to large joints: report of three cases and review of the literature.

Para-articular chondroma is a rare tumor that has been reported in only 30 cases adjacent to large joints in the Anglo-Saxon literature. We report three new cases of this entity, describe its clinical, radiological and pathological features, and review the previous literature. Para-articular chondromas have an insidious clinical presentation and on radiographs show a large soft tissue mass with variable ossification. They appear as a lobulated mass of hyaline cartilage with variable endochondral ossification in the central area. These rare benign tumors arise from the capsule or the para-articular connective tissue of a large joint (mainly the knee), which suffers cartilaginous metaplasia and subsequent ossification. Cases 1 and 2 of this presentation fit all the features described previously. Case 3 has identical clinical features but differs from the former two cases in its microscopic appearance, being composed almost entirely of fibrocartilage and myxoid areas within the fibroadipose tissue of the joint instead of mature trabecular bone surrounded by hyaline cartilage. To the best of our knowledge this is the first description of this histological variant of para-articular chondroma.