Dermal melanocyte hamartoma. A distinctive new form of dermal melanocytosis.

An 18-month-old infant had diffuse, gray-blue pigmentation on the buttocks bilaterally, extending the entire length of his right leg in a dermatomal pattern. In the lesion there were several conspicuous macules of considerably darker hue. Histologic and ultrastructural examinations revealed numerous dermal melanocytes. Clinically and pathologically, the patient had a distinctive type of dermal melanocytosis for which we propose the name "dermal melanocyte hamartoma."