Clinical presentation:
24 year old male with Trisomy 21, Mongolism.

There is soft tissue swelling of the soft-tissue over the extensor surface of the olecranon of the ulna. It contains areas of amorphous calcification.

There is destructive change with subluxation in the metacarpo-phalangeal joint of the thumb on the 'left' hand and of the little finger on the 'right' hand. The appearance is a combination of erosive joint disease and destruction of bone by juxtarticular soft tissue masses. Soft tissue calcification is seen in the increased soft tissue adjacent to the distal interphalangeal joint and over the tuft of the distal phalnx of the middle finger in the right hand.

The gross disorganisation of the right 5th metacarpo-phalangeal joint is simply a combination of overgrowth of articular tissue eroding the joint margins and exuberant soft tissue masses adjacent to the joint, eroding and compressing the bone. Obviously the curvilinear density is too large to be displaced bone fragment, but the view does not discriminate any cancellous pattern. The appearance is presumably calcification in a large mass.

There is destruction of the distal interphalangeal joint of 2nd and proximal interphalangeal joint of 5th toes. The remaining joint margins are well-defined. There is calcific density in the soft tissues of the fifth toe. Additional patches of bone loss lie away from the intact margins of remaining interphalangeal and metatarso-phalangeal joints.