Nodular melanoma, unlike superficial spreading melanoma, is typically round, elevated, red or pink, and uniform in color. Courtesy Dr. Sally McCormack
GLASGOW, SCOTLAND — The success in recent years of public- and professional-relations efforts to spread awareness of early signs of melanoma has had one unfortunate downside: The common checklists that identify worrisome features of skin lesions do not apply to the highly lethal nodular form of the disease, according to Sally McCormack, M.B., and her colleagues at the department of dermatology, Royal Infirmary of Edinburgh in Scotland.
Educational efforts aimed at increasing the early recognition of melanoma during the past 20 years have been beneficial, with many more early, thin lesions being identified and removed. Mnemonics like “ABCD”—asymmetry, border irregularity, color variation, and diameter exceeding 6 mm—are helpful tip-offs for the more common forms of the disease, such as superficial spreading melanoma.
But these criteria do not apply to nodular melanomas, which typically are round, elevated, red or pink, and uniform in color throughout. They also carry a poor prognosis because they are likely to be deeper when identified—and lesion depth correlates with outcome.
A review of all 3,353 reported cases of melanomas in the Edinburgh area over the past 24 years found that 447 were nodular, Dr. McCormack reported. Unlike previously reported incidence rates, women were more commonly affected, with the male:female ratio being 1:1.24. Breslow thickness was high, with 53.7% of cases being greater than 4 mm and only 1.8% being less than 1 mm. In 25% of the patients, the lesion was less than 10 mm in diameter; in another 24%, the lesion was 10–20 mm in diameter.
The most common sites were sun-exposed areas, such as the head, neck, and distal limbs.
“This is in contrast to the other types of melanoma, which in our district have been occurring more frequently on usually covered sites of the body,” Dr. McCormack wrote in a poster session at the annual meeting of the British Association of Dermatologists.
The mean age of patients tended to rise over time, from 54.7 years in the first 6 years of the survey to 65.9 years in the most recent cohort.
“Thus, over the years the typical nodular melanoma patient has come to be older, less frequently male,” with a relatively small lesion that has a high Breslow thickness on the head and neck or distal limbs, she wrote, adding that these factors should be borne in mind when targeted melanoma education programs are designed in the future.
This difference in lesion distribution raises the question as to whether nodular melanomas are biologically different from other types of melanoma, as some have suggested.