[Pigmented villonodular synovitis causing ankle pain].

A rare case of diffuse pigmented villonodular synovitis is described. Because of unspecific symptoms as oedema and pain and uncertain relation with trauma the diagnosis was delayed for almost two years, until a MRI showed diffuse hypodense infiltrative lesions involving soft tissue structures around the ankle. Treatment was a radical open synovectomy of the ankle and subtalar joints and tenosynovectomy of the tendons around the ankle.