Painful extraskeletal osteochondroma under the tarsal sesamoid: a case report and review of literature.

Extraskeletal osteochondroma is a rare condition. To our knowledge, occurrence in the foot has been very rare. We present here a case wherein the patient developed a painful extraskeletal osteochondroma under the tarsal sesamoid. A fifty-one-year-old man presented at our department with a painful mass on the plantar part of the metatarsal joint of the right big toe. The mass had grown gradually in size for the past 7 months and was associated with pain while walking. Preoperative X-ray and a computed tomography showed that the tumor had no continuity with adjacent bone. Intraoperatively, a bony hard tumor was located in the subcutaneous tissue plantar to the tibial sesamoid. The mass was firmly attached to the sheath of the flexor hallucis brevis tendon. Macroscopically, the tumor was covered with glistering surface. The tumor was carefully dissected from the surrounding soft tissues and was removed. It was diagnosed as extraskeletal osteochondroma histologically. The patient had no recurrence at 1 year after operation.