KAUAI, HAWAII (FRONTLINE MEDICAL NEWS) Children born with two or more melanocytic nevi of any size should have an MRI to check for brain lesions, ideally within the first 6 months, according to Jennifer Huang, MD, a pediatric dermatologist at Boston Children’s Hospital.

Two or more nevi increase the risk of CNS involvement, which in turn increases the risk of malignant conversion by more than 16-fold.

Dr. Huang’s advice came during a presentation at the Hawaii Dermatology Seminar provided by the Global Academy for Medical Education/Skin Disease Education Foundation.

Among the studies she cited was a 2017 literature review of 448 children with congenital nevi, 10 of whom developed melanoma: It arose in the skin in 2, the brain in 6, and an unknown location in 2. All 10 children were born with two or more nevi, and not all of them had large or giant nevi, which is a known risk factor for malignant conversion (Br J Dermatol. 2017 May;176[5]:1131-43).

“If the scanning brain MRI is normal, [children] might not have congenital melanocytic nevus syndrome, and would be at low risk for melanoma,” Dr. Huang said. “If it’s abnormal, they might be at high risk for melanoma.” In the 2017 study, the odds ratio for melanoma with an abnormal MRI was 16.7 (P = .001).

Both melanocytes and neuronal cells arise from the embryonic neural crest, which explains the link between congenital nevi and brain lesions. Almost all congenital nevi are associated with early postzygotic mutations in the NRAS gene, and it’s possible the mutations affect other neural crest cell lines, including in the CNS, she said.

It’s also important to remember that childhood melanoma often doesn’t follow the ABCDE (asymmetry, border irregularity, color not uniform, diameter greater than 6 mm, and evolving) signs of melanoma common in adults.

In a retrospective study of 70 children with melanoma or ambiguous melanocytic tumors, 40% of pubertal subjects and 60% of prepubertal participants did not meet conventional adult ABCDE criteria. The majority of cases were raised, even in color, less than 6 mm across, symmetric, and de novo ( J Am Acad Dermatol. 2013 Jun;68[6]:913-25 ).

It turns out that rapid evolution in size, shape, and color is the number one, unifying factor in childhood melanomas. Other key clues include raised lesions with uniform color or no pigmentation at all. A modified ABCDE for pediatric melanoma has been proposed: amelanotic, bump/bleeding, color uniform, diameter variable, de novo, and evolution.

“The lesson to learn is not to ignore the traditional ABCDEs of melanoma, but to recognize that pediatric melanoma may present with different clinical characteristics, and to incorporate this awareness into our practice,” Dr. Huang said.

She did not have any disclosures. SDEF/Global Academy for Medical Education and this news organization are owned by the same parent company.


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