Dysplastic nevus presents with architectural disorder under the microscope

March 1, 2006

Baltimore ? A lack of consensus on what to call a specific type of mole is indicative of the inability of dermatologists to agree on the best way to treat atypical moles, which can be an indicator of an increased risk of melanoma.

Nearly 30 years after Wallace Clark, M.D., initially identified and described the "B-K mole syndrome" of familial melanoma, doctors still can't agree whether nevi with architectural disorder - the designation recommended by the National Institutes of Health Consensus Conference - are simply markers of a tendency to develop melanoma or if the moles themselves are pre-malignant.

Because the controversy continues today and doctors cannot come to an agreement on that score, neither can they reach an agreement on the best approach to treatment.

A clinical professor of pathology and dermatology at the University of Texas Southwestern and head of dermatopathology for ProPath Services, a private pathology group practice, Dr. Barrett acknowledges that patients with a family history of nevi with architectural disorder, especially those whose parents developed melanoma, have reason to be concerned that they too might develop the potentially fatal carcinoma.

"If both of a patient's parents have the atypical moles and both developed melanoma, the patient with the syndrome has nearly a 100 percent chance of developing the disease. If just one parent developed melanoma, the risk is about 50 percent - and, even if neither parent has melanoma but had atypical nevi, and the patient has atypical nevi, they still have a markedly increased risk of developing melanoma.

"So there is no question that even without the family history, the dysplastic nevus itself is a marker for a patient who is at increased risk."

Removal, risk reduction

The quandary in which physicians find themselves, however, is that there is no definitive evidence that removing the moles themselves will reduce that risk.

Dr. Barrett explains, "Patients with a parent who has had melanoma will come in with a hundred or more atypical moles scared to death and want to have them all removed - and even if one dermatologist won't do it, some patients will keep looking until they find someone who will. But just because the moles are removed doesn't mean that person has reduced their risk of developing melanoma.

"Thirty percent of the melanomas that develop on patients with atypical moles do so on the moles, but that means 70 percent of the melanomas do not develop on the moles."

Part of the problem, says Dr. Barrett, is that the term "dysplasia," in the minds of many, indicates the moles themselves are premalignant.

"As a result, many dermatologists, believing that these are premalignant lesions, will biopsy them. Then, when they get a diagnosis of nevus with architectural disorder, they will re-excise the mole - ensuring its complete removal.

"Dermatologists who don't believe that these are premalignant lesions will biopsy one that looks particularly odd or concerns them. If the diagnosis is melanoma, they will treat the patient. But if the diagnosis is nevus with architectural disorder or dysplastic nevus, those dermatologists will not go back and re-excise that mole - they believe they have simply biopsied the marker. If the lesion is not malignant, they don't do additional treatments."

So patients can get a completely different course of treatment depending on which dermatologist they see.

Lesions unlikely premalignant

Dr. Barrett says his bias is that he has been looking at moles for 22 years and thinks it is unlikely that these specific moles are premalignant lesions.