Extraskeletal osteochondroma of the foot.

An extraskeletal osteochondroma is an infrequently encountered benign cartilaginous tumor with a predilection for the hands and feet that usually does not exceed 3 cm in diameter. This diagnosis can be misleading because it bears the same name as the osseous neoplasm more commonly referred to as an exostosis. The authors present an unusual case of a painful enlarging mass in the foot of a 28-year-old man who was later diagnosed as having an extraskeletal osteochondroma measuring in excess of 4 cm. Clinical, radiographic, and magnetic resonance images are provided along with intraoperative and histopathologic figures. There was no sign of recurrence 1 year after surgical excision. A review of the literature regarding this uncommon lesion is also presented.