Finger retronychias detected early by 3D ultrasound examination

BACKGROUND: A new pattern of ingrown nail, called retronychia is involved in the posterior translation of the whole nail unit producing paronychia. OBJECTIVE: To demonstrate an unusual case of paronychia that affected three of the fingers on the right hand. METHODS: We used 3D ultrasound to study the whole nail unit in the fingers of both the affected (right) and non affected (left) hand. RESULTS: Backward motion of the nail unit with decreased distance between the origin of the nail plates and the distal interphalangeal joint was clearly demonstrated by 3D ultrasound in the affected fingers. CONCLUSION: 3D ultrasound provides non invasive and more understandable information about the physiopathological changes in retronychia.