Epidermoid cyst mimicking monoarticular arthritis of the great toe.

Local swellings of the foot are a common presentation in rheumatological practice. In the following case report, an epidermoid cyst presenting with the typical features of monoarticular arthritis is described in a 27-year-old woman. The differential diagnosis of forefoot swelling is discussed, with particular emphasis on epidermoid cysts and monoarticular arthritis.