Even in the most experienced hands, dermoscopy poses a challenge when the usual pigment clues are lacking to help distinguish melanoma from amelanotic melanoma and pigmented basal cell carcinoma (BCC) from nonpigmented BCC.
“For me, pink lesions are challenging,” Jennifer A. Stein, MD, PhD, said during the virtual Orlando Dermatology Aesthetic and Clinical Conference. “How can dermoscopy help us distinguish between Spitz nevus, melanoma, clear cell acanthoma, psoriasis, basal cell carcinoma, and squamous cell carcinoma?”
Stein, professor of dermatology at New York University, offered four tips. First, look for the shiny white perpendicular lines, otherwise known as the chrysalis or crystalline pattern. “You can only see this feature when you’re looking with polarized light,” she said. “This is why you want a dermatoscope that has polarized light, and better yet, one that you’re able to turn on and off, the hybrid kind, because then you can convince yourself that you’re looking at this feature, because it blinks on and off.”
The differential diagnosis for white shiny perpendicular lines includes dermatofibroma/scars (which is most common), Spitz and atypical genital nevi, BCC, and melanoma. “Dermatofibromas sometimes have white circles or rings in the center,” Stein said. “In BCC, the lines aren’t always perpendicular. Sometimes it’s more of a blotch or strands.”
A second tip for managing a pink lesion on dermoscopy is to look for any brown color. “When you see that combo together you have to worry,” she said. “When you see pigment network on dermoscopy, you have to put melanoma in your differential. If you see shiny white lines in something that is melanocytic, there’s a 98% specificity for melanoma.”
A third tip she offered for managing pink lesions is to check the blood vessels for clues. “For years, I was just naming the vessels based on making the diagnosis and then deciding, ‘that’s a basal cell carcinoma; those must be branching vessels,’ ” said Stein, who manages NYU’s medical dermatology faculty group practice.
However, blood vessel patterns differ. For example, branching or arborizing vessels are suggestive of BCC. “These vessels are very crisp-looking on dermoscopy,” she said. “They’re all in the same plane of focus and they look like they were drawn in with a fine point marker. That’s different from other blood vessel patterns.” She also pointed out that superficial basal cells have short, fine telangiectasias. “When you put on the polarized light, the clue is the white, shiny structures,” she said.
Dotted vessels, meanwhile, appear on dermoscopy as small red dots aligned perpendicular to the skin surface. The differential includes inflammatory lesions like psoriasis, stasis, and trauma; clear cell acanthoma (characterized by a “string of pearls” arrangement), nevi, and melanoma. “I find dermoscopy most useful in diagnosing SCC – especially squamous cell in situ,” she said. “Important clinical clues suggestive of SCC or melanoma include a solitary lesion, it’s new, it’s growing, and it’s not going away with a topical steroid.”
An additional pattern to be aware of are hairpin vessels, which are looped and feature a sharp bend at one end. These are often seen in seborrheic keratoses. “You can’t count on the hairpin vessels alone, because you can see this in anything keratotic, such as in keratoacanthoma (at the periphery with a yellow keratotic center), warts, SCC, BCC, as well as in dermal nevi and Spitz nevi,” said Stein, who recommended dermoscopedia.org as resource.
Comma vessels, meanwhile, appear in dermal or compound nevi. She described these as “slightly curved vessels that are much less in focus than branched vessels, because they come in and out of the plane of focus,” she said. “If you put your dermatoscope on top of the nevus and wobble it around you can appreciate the curve. If you look at it from the side, it looks like a curve. If you look at it straight on it will look more like a line. If you look at from the end it will look like a dot.”
Another vessel type she discussed are linear irregular and polymorphous vessels, which she described as “any combination of different types of vessels. We get most worried when we see dotted and linear irregular vessels together. In that case, you worry about melanoma. These can also be seen in nevi and other tumors, such as BCC.”
Stein’s fourth tip of the presentation was a reminder to consider dermoscopy as one piece of the clinical exam. “Always think about the lesion in context of the rest of the clinical picture and history,” she said. “Don’t get discouraged if it’s hard; just keep practicing. Look for any brown and use your clinical clues to put together to make the right decision.”
She disclosed that NYU receives compensation from MoleSafe for her telemedicine dermoscopic diagnoses.
This article originally appeared on MDedge.com, part of the Medscape Professional Network.