Using Dermoscopy in Skin of Color to Differentiate Pigmented Lesions From Skin Cancer

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Distinguishing pigmented lesions from melanoma, pigmented squamous, or pigmented basal cell skin cancers can be difficult and it takes more than pattern recognition alone to make the distinction. Successfully utilizing dermoscopy, especially in skin of color, is key in making that differentiation.

Orit Markowitz, MD, CEO and founder of Markowitz Medical in New York, New York, discussed how to use skin of color dermoscopy to examine pigmented lesions in her talk at the Society of Dermatology Physician Assistants (SDPA) 20th Annual Fall Dermatology Conference, held November 17-20, 2022, in Miami, Florida.

Markowitz opened with a look at the genetics of melanoma and the MC1R gene, specifically how a high nevi count coupled with MC1R red hair alleles can contribute to an increased risk of melanoma.

She then detailed how the recognition of basal cell carcinoma (BCC) hinges on a handful of identifying characteristics, including:

• Absence of pigmented network
• Leaf-life structures
• Large blue-gray ovoid nests or globular-like structures
• Arborizing (tree-like) telengectasias (sharp)
• Spoke wheel areas
• Ulceration
• Ping-white to white shiny areas
• Crystalline patterns

To distinguish malignant from benign, Markowitz suggests running through a few steps to evaluate whether the ­lesion is flat or elevated, its color, as well as its pattern. Color is especially important, as some pigmented lesions can appear differently with the aid of dermoscopy.

When identifying dermatofibroma, it is important to look for a central white patch, a pigmented network or network-like structures, ring-like globules, crystalline pattern, or vessels and erythema when using dermoscopy.

Meanwhile, pigmented bowens present under dermoscopy with a smudged border and small brown globules.

Markowitz spent some time discussing acral lesions, which occur primarily on the palms, soles, fingers, and toes. Some hallmarks of benign melanocytic patterns include parallel furrow, lattice, and fibrillar. Malignant melanocytic patterns, meanwhile, include parallel ridge; diffuse pigmentation that “does not respect” the lines; variable shades of brown, black, or blue; and peripheral dots/globules of various size and shape irregularly distributed.

At first sight, subcorneal hemmorhage can sometimes be confused for a malignancy, but typically have the following characteristics under dermoscopy: yellow-red/red-black, globules at the periphery, or black heel (tale noir). 

It’s also important to examine patients’ fingernails, Markowitz stressed, as melanoma can present under the nail beds.

“I find nails to be very challenging,” she said. “If it is malignant melanoma, it’s very life threatening and sometimes caught quite late because many patients are coming in with nail polish on for their skin exam…You have to remember to ask, ‘do you have any pigment under your polish?’”

Reference:

Markowitz O. “Skin of Color.” Presented at the 2022 Society of Dermatology Physicians Assistants Conference; November 17-20, 2022. Miami, Florida.