Accessory navicular bone: when ankle pain does not originate from the ankle.

A young girl suffering from ankle pain occurring after gymnastics classes was referred to the rheumatology department by an orthopedic surgeon because a rheumatological condition was suspected to cause her symptoms. MRI was useful in pointing to the correct diagnosis of accessory navicular bone (AN). The morphological classification of ANs is discussed and the imaging modalities for diagnosis are presented.