Some melanomas present as harmless-looking pimple

Source: Dermatology Times, May 2014

Researchers in Australia are cautioning about an aggressive form of melanoma that looks like a pimple, leading many doctors to dismiss it as harmless.

According to the study, led by associate professor John Kelly, M.D., of the Victorian Melanoma Service, the lesions usually present as red nodules rather than the dark, ugly moles typical of melanoma. This can lead doctors to mistake the lesions for relatively harmless forms of skin cancer or even pimples.

Seeking to compare dermoscopic characteristics of nodular squamous cell carcinoma (SCC) and keratoacanthoma (KA), Dr. Kelly and colleagues did a retrospective analysis of 50 nodular SCC and eight KA collected from a dermatology referral center and a private dermatology practice in Melbourne, Australia, from September 2009 to October 2012. Two examiners in consensus evaluated clinical and dermoscopic images.

The researchers found that signs of keratinization were common in both SCC and KA. Vascular structures were often polymorphic in both SCC and KA lesions, and hemorrhage was common in both.

“Keratinization, hemorrhage and polymorphic vascular structures … are common dermoscopic features shared by both nodular SCC and KA,” study authors concluded. “Dermoscopy does not reliably differentiate between SCC and KA.”

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Dr. Kelly is quoted in an Australian news report as saying that if the red nodules are firm and growing progressively for more than a month, they should be checked as a nodular melanoma.

“I agree with just about everything Professor Kelly (says), especially the fact that anything ‘progressively growing for a month’ should be investigated,” Ronald G. Wheeland, M.D., of the University of Missouri’s department of dermatology, tells Dermatology Times. “However, I personally wouldn’t stop there. The American Academy of Dermatology has for some time been promoting the ‘ABCDEs’ of melanoma to help patients determine which growths, including ‘pimples,’ are worthy of investigation.”