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Database of Congenital Nevi Shows Malignant Potential

Database of Congenital Nevi Shows Malignant Potential

NEW ORLEANS—Because 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-bases—the New York
University Registry and the worldwide Nevus Outreach Registry (www.nevus.org)—have
yielded very valuable information.

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