Agminated blue nevi: case report and review of the literature.

Blue nevi may rarely appear in multiple form and grouped in a circumscribed area, a pattern of arrangement that is more properly designed under the term agminated blue nevi. In this paper a new case with light and ultrastructural studies is described, and the previously reported cases are reviewed. Histologically, there was a characteristic perifollicular arrangement of dermal melanocytes, most of which showed ultrastructurally an extracellular sheath.