Recent study shows malignancy risk of congenital lesions lower than believed

Recent research is changing the conventional wisdom about the malignancy risks of congenital lesions. As a result, pediatric dermatologists are re-evaluating their treatment approaches to these lesions.

Nevus sebaceous "In the past, it was estimated that these lesions had a very high risk of malignant change - in the 10 to 30 percent range. In the last five years, however, the literature reports that many of the lesions we called basal cell carcinoma were actually benign, (Jaqueti G, Requena L, Sanchex Y. Am J Dermatopathol. 2000;22:108)," Dr. Wagner says.

Because they aren't malignant doesn't mean the lesions should all be left untreated.

Dr. Wagner says changes will occur during puberty that can be cosmetically important.

"Nevus sebaceous is most common in the scalp," she tells Dermatology Times. "If you have a section that does not grow hair, and during puberty the lesion starts to grow wart-like lesions, it's unlikely your adolescent is going to be happy leaving it there."If the nevus sebaceous is bigger than one centimeter in infancy, Dr. Wagner still recommends removal.

"I make sure parents are aware the risk of malignancy is only in the 1 percent range - not the previously predicted 15 percent to 30 percent - but that about 30 percent of these lesions will still change appearance and require a biopsy," she explains. "Moreover, the lesions grow with the patient - a 1 cm lesion in an infant can grow to more than 2.5 cm in an adolescent and that creates quite a problem for a teenager."

Dr. Wagner recommends removing any nevus sebaceous on the scalp that is larger than a centimeter during the second half of the first year of life - typically with a general anesthetic.

If a lesion is smaller than a centimeter, she gives the parents more options, including waiting until the child is about 8 years old and removing the nevus under a local anesthetic.

If a parent doesn't plan to have the nevus removed at all, Dr. Wagner makes sure they are aware that any change in the nevi will still require biopsying.

Large congenital nevi - more than 20 cm in an adult

Dr. Wagner says medical literature varies greatly in the assessment of congenital nevi and she's not convinced that The New York University Registry, designed to better assess the true risk of malignancy in these lesions, is going to add much to the understanding of the risks associated with the large congenital nevi.

In large nevi, Dr. Wagner says the estimated risk of malignancy from older reports in the literature ranges from 8 percent to 14 percent, while the Registry is reporting a 2.3 percent risk. (Bittencourt FV, Marghoob AA, Kopf AW, et al. Pediatrics,2000:106;736.) According to Dr. Wagner, dermatologists should be skeptical of that figure.