WAIKOLOA, HAWAII – The dermoscopic features that reliably distinguish malignant mucosal lesions are a combination of structureless areas within the lesion along with blue, gray, or white color, a multicenter study conducted by the International Dermoscopy Society has shown.
This combination of dermoscopic findings yielded 100% sensitivity for histopathologically confirmed melanoma and 93% sensitivity for any malignancy, lead investigator Dr. Andreas Blum reported at the Hawaii Dermatology Seminar sponsored by Skin Disease Education Foundation (SDEF).
He noted that while the key points in dermoscopic differentiation between malignant and benign and pigmented and nonpigmented lesions of the skin, nail apparatus, and scalp are well established, the important features to look for in dermoscopic evaluation of lesions of the oral mucosa and genitalia haven’t been well characterized. That was the impetus for the international observational study.
Consensus regarding dermoscopy of mucosal lesions has lagged for a couple of reasons, explained Dr. Blum, professor of dermatology at the University of Tübingen (Germany). One is that pigmented mucosal lesions are uncommon. And another is that manipulating the dermoscope in mucosal areas can be a challenge.
The study took place at 14 specialized skin cancer clinics in 10 countries. It included 140 patients with pigmented mucosal lesions, of which 126 ultimately proved benign, while 11 were melanomas, 2 were squamous cell carcinoma in situ lesions, and 1 was a metastasis (Arch. Dermatol. 2011;147:1181-7).
The investigators scored the dermoscopic patterns they saw as dots, globules, or clods, circles, lines, or structureless using a pattern analysis method developed by Dr. Harald Kittler.
The key study finding was that in a univariate analysis, lesions that were blue, white, or gray in color under the dermoscope and that contained structureless zones had a 100% sensitivity for melanoma, a 93% sensitivity for any malignancy, and an 83% specificity for being benign.
"When you see structureless areas – and only part of the lesion needs to be structureless – with blue, gray, or white zones, then you know something has gone wrong and it’s time to do a biopsy or excision," he said.
Recognizing structureless areas might be at times a difficult call for less-experienced physicians to make, the investigators also analyzed the data based solely upon a lesion’s color. Blue, gray, or white still had a sensitivity of 100% for melanoma and 93% for any malignancy, but the specificity dropped to 64%.
"So if you’re unsure about whether you’re seeing a structureless area, based upon color only, you’ll reliably detect melanomas and other malignancies, but you’ll end up doing unnecessary biopsies for benign lesions," Dr. Blum explained.
He credited Dr. Alfred W. Kopf of New York University with a suggestion that has made dermoscopic evaluation of mucosal lesions much more practical. To avoid contaminating the lens of the dermoscope, simply wrap the head of the device in plastic food wrap that has been coated on both sides with mineral oil.
Session chair Dr. Ashfaq A. Marghoob, a coinvestigator in the international study, offered a cautionary tale. He said that he has had two teenage patients with vulvar pigmented lesions that looked clinically like a clear-cut melanoma, and dermoscopically like melanoma, and the pathology report on the biopsy specimen came back as melanoma. Yet an alert gynecologic surgical oncologist contacted him and said he thought the white area surrounding the pigmented lesion looked like lichen sclerosus et atrophicus. It turned out the surgeon was right.
"I saw the patients again, and lo and behold it was as obvious as could be. I had missed the LS & A [lichen sclerosus et atrophicus], because I was so focused on the pigmented lesion that I just hadn’t realized it was there. It turns out that if you have LS & A, you can develop pigmented lesions within it that look like melanoma clinically, that look like melanoma under dermoscopy, and look like melanoma histologically," said Dr. Marghoob, a dermatologist at Memorial Sloan-Kettering Cancer Center in New York.
The surgery planned for one of these young patients entailed removal of the clitoral area, so timely recognition that she actually had LS & A and not melanoma spared her from a life-changing mistake.
"We’ve now been following her for 5 years, and she’s absolutely fine with no change in the pigmented lesion," he noted.
The lesson he said he’d like to share: "A vulvar melanoma in somebody under the age of 50 is almost unheard of, and I’d strongly consider LS & A instead, checking with a Wood’s light."
Neither Dr. Blum nor Dr. Marghoob reported having any relevant financial disclosures. SDEF and this news organization are owned by Elsevier.