Distal defect of the humerus, a possible normal variant: a case report

BACKGROUND: Many normal variants of bones on plain radiographs have been reported. CASE PRESENTATION: In the current report, a 14-year-old Asian girl noticed an occasional slight elbow pain. She had no traumatic episode. Plain radiographs showed a well-defined osteolytic lesion with a sclerotic rim, which was continuous with the normal subarticular bone in the distal humerus. Magnetic resonance imaging revealed that the defect area seen on the plain radiograph showed low-signal to iso-signal intensity on T1-weighted images and slightly high-signal intensity on T2-weighted fat suppression images. Bone edema was not observed. The association between her elbow pain and the lesion was not conclusive. CONCLUSIONS: The findings from the images suggested that the lesion was a normal variant rather than osteochondritis dissecans or a neoplastic lesion, and possibly an anatomical counterpart of a dorsal defect of the patella.