Dermoscopic evaluation for detection of hypomelanotic and amelanotic melanomas is less accurate than for pigmented melanomas, but its utility can be boosted by familiarity with a handful of dermoscopic features specific to melanomas lacking significant pigment, Steven Q. Wang, MD, said at MedscapeLive’s annual Las Vegas Dermatology Seminar, held virtually this year.

Dr. Steven Q. Wang, Memorial Sloan Kettering Cancer Center, Basking Ridge, NJ

Dr. Steven Q. Wang

These features emerged from a major study conducted on five continents by members of the International Dermoscopy Society. The investigators developed a simple, eight-variable model, which demonstrated a sensitivity of 70% and specificity of 56% for diagnosis of melanoma. And while that’s a markedly worse performance than when dermoscopy is used for detection of pigmented melanomas, where sensitivities in excess of 90% and specificities greater than 70% are typical, it’s nonetheless a significant improvement over naked-eye evaluation of these challenging pigment-deprived melanomas, noted Dr. Wang, director of dermatologic surgery and dermatology at Memorial Sloan Kettering Basking Ridge (N.J.)

Using the predictive model developed in the international study to evaluate lesions lacking pigment, a diagnosis of melanoma is made provided two conditions are met: The lesion can have no more than three milia-like cysts, and it has to possess one or more of seven positive dermoscopic findings. The strongest predictor of melanoma in the study was the presence of a blue-white veil, which in univariate analysis was associated with a 13-fold increased likelihood of melanoma.

The other positive predictors were irregularly shaped depigmentation, more than one shade of pink, predominant central vessels, irregularly sized or distributed brown dots or globules, multiple blue-gray dots, and dotted and linear irregular vessels.

Dr. Wang emphasized that, when dermoscopy and clinical skin examination of a featureless hypomelanotic or amelanotic lesion yield ambiguous findings, frequent vigilant follow-up is a viable strategy to detect early melanoma – provided the lesion is superficial.

“The reality is not all melanomas are the same. The superficial spreading melanomas and lentigo melanomas grow very, very slowly: less than 0.1 mm per month. Those are the types of lesions you can monitor. But there is one type of lesion you should never, ever monitor: nodular lesions. They are the type of lesions that can do your patient harm because nodular melanomas can grow really fast. So my key takeaway message is, if you see a nodule and you don’t know what it is, take it off,” the dermatologist said.

Dermoscopy in the hands of experienced users has repeatedly been shown to improve diagnostic accuracy by more than 25%. But there is an additional very important reason to embrace dermoscopy in daily clinical practice, according to Dr. Wang: “When you put the scope on an individual, you slow down the exam and patients feels like you’re paying more attention to them.”

That’s worthwhile because the No. 1 complaint voiced by patients who make their way to Sloan Kettering for a second opinion is that their prior skin examination by an outside physician wasn’t thorough. They’re often angry about it. And while it’s true that incorporating dermoscopy does make for a lengthier skin examination, the additional time involved is actually minimal. Dr. Wang cited a randomized, prospective, multicenter study which documented that the median time required to conduct a thorough complete skin examination without dermoscopy was 70 seconds versus 142 seconds with dermoscopy.

Dr. Wang reported having no financial conflicts regarding his presentation.

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