Subungual and periungual congenital blue naevus.

Subungual pigmented lesions should raise concern about malignant melanoma. Blue naevus of the nail apparatus is a rare entity, with only ten cases described in the literature. We report a 21-year-old Hispanic woman with a slowly enlarging 1.7 x 2.3-cm subungual and periungual pigmented plaque present since birth on her right second toe. Initial biopsy was consistent with a blue naevus of the cellular type and, given the recent clinical change and periungual extension, complete excision was recommended. The entire nail unit was resected down to periosteum with prior avulsion of the nail plate. Reconstruction was performed with a full-thickness skin graft. Follow up at 1 year revealed well-healed graft and donor sites with complete return of function. We present a case of a congenital subungual and periungual blue naevus of the cellular type and review the literature on this rare presentation of a congenital blue naevus.