Polymyositis associated apatite arthritis.

A patient with polymyositis of 12 years' duration developed inflammatory polyarthritis confined to the hands and wrists, with erosions and periarticular calcifications. Her joint disease exemplified that of a previously described subset of patients with polymyositis associated arthritis. In this case, calcific material was aspirated from the right long finger proximal interphalangeal joint and the mineral was analyzed and identified as apatite.