This black lesion had been present on the upper back of a 5-year-old girl since birth. The lesion had gradually enlarged to its current size of 1.5 cm. In the past year, 3 satellite black macules had developed in the surrounding area.
A biopsy of the lesion showed proliferation of nested melanocytes in the dermis, characteristic of an intradermal melanocytic nevus. The parents were reassured that the lesion was benign and were advised to bring the child back for assessment if there was a sudden increase in pigmentation, lesion size, or number of satellite lesions.
Alexander K. C. Leung, MD, and Justine H. S. Fong, MD, of Calgary, Alberta, write that congenital melanocytic nevi are present in 1% to 2% of newborns.1 Lesions may be brown or black and may be flat, nodular, or verrucose. Congenital melanocytic nevi are referred to as dermal, or intradermal, nevi when the proliferation of nested melanocytes is located in the dermis.
Routine removal of small congenital nevi is not warranted because the chance that melanoma will develop is exceedingly rare. Surgical excision is indicated when malignant changes are suspected.