The nidus of an osteoid osteoma mimicking an os supratrochleare dorsale

Abstract

Osteoid osteomas arising in an intra-articular or paraarticular site can present a diagnostic problem, particularly when occurring around the elbow. The adjacent joint can show evidence of synovitis and proliferative arthritis, and on radiographic examination new bone formation may be slight or absent and the nidus invisible (Marcove & Freiberger, 1966; Moreton & Bartlett, 1966; Corbett et al, 1974; Cronemeyer et al, 1981; Clarke et al, 1981). These atypical features can lead to misdiagnosis of this condition. We present a further cause of misinterpretation of osteoid osteomas around the elbow, that of the nidus mimicking an os supratrochleare dorsale.