Dermoscopy detects melanoma incognito

Using a dermoscope can help dermatologists diagnose melanomas that don't exhibit classic warning signs, says an expert.

"Everyone who does dermoscopy uses it for lesions that look clinically atypical," says Robert Johr, M.D., clinical professor of dermatology and pediatrics at the University of Miami, and a Boca Raton, Fla.-based private practitioner. "However," he says, "we saw seven cases in which we used dermoscopy on lesions that didn't look particularly worrisome clinically, and to our surprise diagnosed melanomas (submitted for publication)."

Melanoma incognito consists of lesions that lack clinical clues suggesting they might be high-risk, Dr. Johr says. "But if one looks at this type of lesion with dermoscopy," he says, "there might be clues that raise one's index of suspicion enough to warrant a histopathologic diagnosis."

To help colleagues diagnose melanoma incognito, Dr. Johr offers these tips:

• Dermoscopy should not only be used for suspicious skin lesions. A patient had a small, unchanged congenital melanocytic nevus. Under a dermoscope, "The lesion had areas with the globular pattern that we expected. But to our surprise, we also saw a bluish-white color that is considered a melanoma-specific criterion," Dr. Johr says.

• Biopsy lesions missing good clinico-dermoscopic correlation. "We had a patient who came in for a routine skin examination," Dr. Johr says. Upon examining a few banal-looking nevi with dermoscopy, he says that in one lesion, "We saw foci of bluish color, brown to black globules and whitish lines at the periphery."

• Nonspecific global pattern. A patient with a history of melanoma presented for a routine follow-up. Dr. Johr says, "Dermoscopic examination of a light lesion on her back revealed it to have foci of structureless brown color at its center and globules at its periphery. This pattern didn't fit into any of the general patterns that we could associate with being benign," he says.

• Starburst pattern. A patient presented with typical-looking nevi. However, dermoscopy showed that one lesion on her forearm had a starburst (Spitzoid) pattern.

• Unexpected regression. In a female patient with nevi that looked only slightly atypical clinically, dermoscopy found one lesion had areas of regression, with whitish and grayish color representing scarring.

• Pigmented lesion changes tracked through digital imaging. One might not be able to diagnose melanoma clinically or with a single dermoscopic session, Dr. Johr notes. "But by tracking changes over time, one might find melanomas," he says.

• Pink lesions. "If one sees pink color clinically or with dermoscopy," Dr. Johr says, "it should raise a red flag." Pink macules and papules could be melanocytic, non-melanocytic, benign, or malignant, as well as inflammatory, he says. "Vascular patterns are very important, and can aid in the dermoscopic differential diagnosis," he adds.

In conclusion, Dr. Johr says, "One should use dermoscopy not only for clinically suspicious lesions, but also for lesions that don't appear suspicious. I do not believe that anyone who has taken the time to learn the technique would argue that it is not a better way to practice dermatology." DT

Disclosure: Dr. Johr reports no financial interests relevant to this article.

Dr. Johr will be director of WRK403 today, with David L. Swanson, M.D. speaking.