Retronychia: a rare cause of chronic paronychia.

Retronychia, described in 1999, is a rare entity of ingrown toenails. Embedding of the nail into the proximal nail fold (PNF) leads to chronic inflammatory changes. Herein, we report a new case that exhibited persistent paronychia in a 23-year-old woman. Retronychia usually does not recur once treated with avulsion. It should be suspected in the event of chronic proximal paronychia.