LAHAINA, HAWAII – Multiple but there are still some “nonbelievers,” Ashfaq A. Marghoob, MD, said at the Hawaii Dermatology Seminar provided by Global Academy for Medical Education/Skin Disease Education Foundation.
In fact, not one study has shown that dermoscopy is less sensitive than the naked eye alone, and at clinics where dermoscopy is used, “two-thirds of the melanomas being detected now lack the classic ABCD features of melanoma,” added Dr. Marghoob, director of clinical dermatology at Memorial Sloan Kettering in Hauppauge, N.Y.
Dr. Marghoob cited a meta-analysis of 9 prospective trials, which concluded that dermoscopy was more accurate in diagnosing melanoma than the naked eye alone and did not lower specificity, with a sensitivity and specificity of 90%, compared with 71% and 81%, respectively for the naked eye (Br J Dermatol. 2008 Sep;159[3]:669-76).
“And at least from an evidence-based standpoint ... the Cochrane library has basically endorsed that, yes, dermoscopy does indeed improve your diagnostic accuracy,” Dr. Marghoob said.
He referred to a 2018 Cochrane review on 104 dermoscopy studies, with and without visual inspection, for diagnosing melanoma in adults (Cochrane Database Syst Rev. 2018 Dec 4;12:CD011902). The review authors concluded that “the evidence suggests that melanomas will be missed if visual inspection is used on its own,” and despite limitations in the evidence, “dermoscopy is a valuable tool to support the visual inspection of a suspicious skin lesion for the detection of melanoma and atypical intraepidermal melanocytic variants.”
As for the question of specificity, Dr. Marghoob said studies have found that dermoscopy results in the detection of more melanomas and reduces the number of biopsies of benign lesions and “every study looking into this has shown that, yes, it does improve” specificity.
A 10-year multicenter survey of about 300,000 cases, which included 17,172 melanomas and 283,043 melanocytic nevi, found that the number-needed-to-excise (NNE) values improved over time in specialized clinics where newer diagnostic techniques like dermoscopy were used (from 12.8 to 6.8), but the NNE did not appear to change in the nonspecialized settings (J Am Acad Dermatol. 2012 Jul;67[1]:54-9).
Looking at the benign-to-malignant ratio, there was no change among those not using dermoscopy, where the ratio remained at about 30 to 1. When dermoscopy was used, this ratio started to improve over the 10-year period, to about 5 to 1. In addition, “the dermoscopy users were finding many more melanomas than the non–dermoscopy users,” Dr. Marghoob added. And over the 10 years, the number of nevi being removed did not change among those not using dermoscopy but dropped among those using dermoscopy.
Adding photography with the ability to digitally monitor patients helps bring this ratio down further, Dr. Marghoob noted. He referred to a study that instead evaluated the ratio of melanoma to nonmelanomas diagnosed among dermatologists in three groups: those with no digital dermoscopy with little dermoscopy training (group A, the reference group), no digital dermoscopy but more dermoscopy training (group B), and those using digital dermoscopy (group C). In the group that used digital dermoscopy, that ratio was about 1 to 2.4, compared with about 1 to 8 in group B, and about 1 to 10.7 in group A (Br J Dermatol. 2012;167[4]778-86).
The use of dermoscopy is also associated with thinner tumors. Among dermoscopy users, the thickness of the tumors detected drops, and the proportion of thin to thick lesions detected increases, Dr. Marghoob said.
For example, in one study, the mean thickness in melanomas detected with dermoscopy was 1.4 mm versus 2.59 mm when dermoscopy was not used (J Eur Acad Dermatol Venereol. 2015 Jan; 29[1]:102-8). About 55% of the tumors detected with dermoscopic examination were 1 mm or less in thickness versus 23.4% of those detected without dermoscopy, “so the dermoscopy users from a proportion standpoint were also finding thinner tumors,” Dr. Marghoob said. Dermoscopy was also identified as an independent predictor of finding thinner tumors.
Even without a study, it could be assumed that the use of dermoscopy would reduce costs, since dermoscopy increases sensitivity and the total number of melanomas detected, decreases the number of benign nevi removed, and helps detect disease earlier. But there are data showing that dermoscopy reduces health care costs, Dr. Marghoob said.* For example, a Belgian study that looked at dermoscopy in two cohorts of melanoma patients concluded that adequate dermoscopy training was cost effective (Eur J Cancer. 2016 Nov;67:38-45).
It has also been shown that adding dermoscopy to a primary care setting has cost benefits, Dr. Marghoob said. He cited a study of Dutch general practices that found that the probability of a correct diagnosis was 1.25 times higher when dermoscopy was used to evaluate suspicious skin lesions and concluded that the use of dermoscopy appeared to be cost effective (J Eur Acad Dermatol Venereol. 2014 Nov;28[11]:1442-9).
Dr. Marghoob had no disclosures relevant to this presentation.
SDEF/Global Academy for Medical Education and this news organization are owned by the same parent company.
*Correction, 2/28/20: An earlier version of this article mischaracterized the cost implications of dermoscopy use.