[Nail unit blue melanocyte nevi: 2 case reports].

INTRODUCTION: Nail unit blue nevus is a rare and benign melanocyte proliferation of the nail unit matrix. OBSERVATIONS: We report two cases of nail matrix blue nevi with a blue-black spot of the lunular area associated in the first case with a longitudinal nail groove. COMMENTS: The analysis of our cases and of the previously reported cases give us the opportunity to describe different clinical and histological presentations.