Giant osteochondral body in a popliteal cyst.

Popliteal cysts, although commonly seen, are rarely associated with motion restriction or calcification. Radiological features are of soft-tissue swelling, with occasional reports of calcifications or small osteochondral bodies inside the cysts. We report a giant osteochondral body in a popliteal cyst, with significant mechanical block to flexion. This type of mass has to be differentiated from synovial osteochondromatosis, calcifications in the cyst, extraosseous and intraarticular osteochondromas. Complete excision of the cyst resulted in complete recovery of range of motion.