Giant cell tumor of the EDL tendon sheath: an unusual cause of hallux valgus.

Hallux valgus is a lateral deviation of the proximal phalanx of the first metatarsophalangeal joint. It is a common disorder in adults. The etiologic factors include modern shoes, rheumatoid arthritis, pes planus, metatarsus primus varus, and trauma. Tumors causing hallux valgus deformities are unusual. We report a 50-year-old female with a hallux valgus deformity caused by a giant cell tumor of the second EDL tendon sheath. Surgical excision of the tumor and corrective osteotomy produced a permanent cure. This unusual cause of a hallux valgus deformity should increase awareness of tumors as a possible cause of foot deformities.