Acquired blue nevus of the nail bed.

Blue nevi are benign proliferations of melaninproducingdendritic melanocytes located in thedermis. These nevi tend to occur mostly on the skin,predominantly on the head and neck, dorsal aspectsof the distal extremities, and the sacral area, butcan also occasionally appear on mucosal surfaces.Blue nevi of the nail apparatus are uncommon. Themajority originate in the nail matrix where there is ahigher density of melanocytes. Herein we report ona 47-year-old man with a rare common blue nevus ofthe nail bed, an area with low melanocyte density. Athorough review of the English language literaturefound no documented cases of acquired blue nevioriginating in the nailbed of the toe.