Extra-articular synovial chondromatosis. Description of a rare localization in the arm.

The author presents a rare instance of extra-articular chondromatosis located around the tendon of the long head of the biceps brachii. The tendon subsequently tore and retracted, resulting in the formation of numerous cartilaginous loose bodies which collected in a mid-brachial cavity communicating with the canal which had previously housed the tendon. The author comments on the peculiar mechanism of production of this rare case of synovial chondromatosis as well as possible interpretations.