NEW ORLEANSBecause of their malignant potential and their cosmetic appearance, congenital nevi elicit much concern from parents. Ashfaq A. Marghoob, MD, assistant professor of dermatology and director of the Pigmented Lesion Group, Memorial Sloan-Kettering Cancer Center, presented new insights into this disorder at a symposium on melanoma held during the American Academy of Dermatology annual meeting.
First 3 Years of Life
While moles that are present from birth are obviously "congenital nevi," Dr. Marghoob extends this definition also to lesions that develop within the first 3 years of life, appear clinically to be congenital, and have a history and histology that are consistent with this assessment.
One of Dr. Marghoob’s patients, for example, had only satellite nevi present at birth, but at 18 months of age developed a 20- to 30-cm mole on her back. "This was the first clinical evidence of a mole that was clinically a congenital nevus but was not evident when I first saw her," he said.
Congenital nevi begin with the melanocytic stem cell in the neural crest. These cells migrate to the leptomeninges and to the embryonic dermis, where they begin to differentiate into melanocytes. After this process, Dr. Marghoob said, the cells migrate up into the epidermis, where they begin forming pigment. The timing of this process is variable; therefore, not all congenital nevi are clinically obvious at birth.
Nevus Outreach Registry
Observations from two large data-basesthe New York University Registry and the worldwide Nevus Outreach Registry (www.nevus.org)have yielded very valuable information.