Pigmented villonodular synovitis of the midfoot.

A 60-year-old man presented with a longstanding slowly growing swelling at the dorsal aspect of the left midfoot. The lesion was imaged with CT, ultrasound, and MR. On CT bony erosions were evident. On MR the lesions appeared bifocal and one component was hypointense on T2 weighted images suggesting hemosiderin deposits. The other component was hyperintense on T2 which is more unusual for PVNS. Imaging findings, however, suggested PVNS which was pathologically confirmed. A unique finding in this case is the late age of presentation of the disorder. Also the bifocal nature of the lesion is relatively uncommon.