Primary synovial chondromatosis of knee with both intra-articular and extra-articular involvement: A case report with delayed diagnosis

Abstract

Primary synovial chondromatosis (PSC) is an uncommon benign disease process of unknown etiology in which the synovium undergoes metaplasia, leading to cartilaginous nodules that progressively undergo detachment, mineralization, and even ossification forming loose bodies. It is usually a monoarticular disease with involvement of large joints with knee being the most common. Involvement of smaller joints such as distal radioulnar, tibiofibular, metacarpophalangeal, and metatarsophalangeal joint has also been reported. This disease process is usually intra-articular. Involvement of extra-articular tissues such as bursae and tendon sheaths is rare, and combination of intra- and extra-articular diseases described here is an extremely rare condition. Herewith, we report a male patient with PSC of left knee with involvement of suprapatellar bursa who presented with recurrent knee swelling and pain with diagnostic delay of 2 years. We have also highlighted the role of imaging in the early diagnosis of this disease and briefly reviewed relevant literature.