Deforming arthritis of the hands in polymyositis.

Arthritis of the hands with erosions, periosteal calcification, and interphalangeal thumb joint instability was seen in 6 patients with polymyositis. "Overlap" features such as Raynaud's phenomenon, positive LE clot test, and positive antinuclear antibody test were present, but clinically the primary disease was clearly polymyositis. This rather unusual constellation of roentgenographic findings strongly suggests the possibility of polymyositis.