Thoughts about genital melanosis on Melanoma Monday
May 1, 2017
Today is National Melanoma Monday — aside from highlighting the importance of melanoma screening, it is a time to celebrate the many lives saved since this day of awareness was established in 1984.
Congratulations to my friend Ken Wasserman, MD, for being recognized with the James R. Andrews Excellence in Baseball Sports Medicine award. Eighteen years ago, he founded Major League Baseball’s skin cancer screening program. Subsequently, more than 41,000 baseball players and team employees have undergone screenings. As the team physician for the Baltimore Orioles, Ken is an indefatigable advocate for sun safety and melanoma prevention. What a well-deserved award!
This commentary, however, will focus on lesions where the sun usually does not shine — genital melanosis, also known as genital lentiginosis or genital melanotic macules. (This will not be a discussion of similar lesions seen in genodermatoses such as the Carney complex.)
Genital melanosis affects both sexes, on the mucosal vulvae and penis. Clinically they may be single or multiple, poorly demarcated macules or patches, with various shades of brown or black, and of varying size. Clinically they may appear dramatically frightening, alarming both the patient and physician about the possibility of melanoma. The most frequent dermoscopic appearance has been described as “ring-like”; a ringed or draped pattern may be appreciated on reflectance confocal microscopy. Histologically there is increased melanin in the basal layer, with a normal or slightly increased number of melanocytes in the basal layer (1). There are two important fiats in the management of genital melanosis — don’t hesitate biopsying them to rule out melanoma; and, if the diagnosis of melanosis is confirmed, conservative, careful clinical follow up and avoidance of mutilating surgery is warranted.
Vulvar melanosis occurs most commonly in perimenopausal women. The pathogenesis of these lesions is unknown (2). Chronic inflammation may be responsible in some cases, as genital lentigines have been observed with resolved annular lichen planus (3) and in patients with lichen sclerosus (4).
Haugh et al performed a retrospective study of 41 patients with genital melanosis. They confirmed that genital melanosis can clinically mimic melanoma but the typical age of onset is younger than for genital melanoma, which is usually in the fifth to sixth decade. A majority of lesions were found to stabilize or regress over time. Five patients were found to have a history of melanoma, only one of which was in the genital region. Lesions from these patients with genital melanosis were more likely to demonstrate suprabasal melanocytes and have a higher melanocyte count histologically. The authors concluded that patients with genital melanosis, and in particular those with any level of histologic atypia in the genital melanosis lesion, may require careful total body skin examinations for the possibility of melanoma in any body site (5). The relatively small number of patients and average time of follow-up (30.5 months) hinder drawing definitive conclusions — nevertheless, prior to reading this paper, I had never thought about a potential increase risk of melanoma at cutaneous sites distinct from the melanosis itself. If confirmed by future studies, this would guide dermatologists to ensure that full body skin exams be encouraged in patients presenting with genital melanosis.
When performing full body skin examinations, do your utmost take the term literally. Of course, respect your patient’s wishes, but offer them the opportunity to have their anogenital region examined. I had gotten out of the habit, but was reminded of the importance of doing so in a recent post (Perianal Dermatological Exams are Looking Up, November 14, 2016). It is the rare patient who has declined the examination when offered (admittedly, I mostly offer this option to men).
On Melanoma Monday, everybody wants to discuss photoprotection. It would also be advantageous to shine light on regions that remain in the dark. Happy screening!
1. Marzaku EC, et al. Vulvar nevi, melanosis, and melanoma: An epidemiologic, clinical, and histopathologic review. J Am Acad Dermatol 2014; 71: 1241-9.
2. García-Rodiño S, et al. Vulvar and areolar melanosis: A case report and review of the literature. J Dtsch Dermatol Ges 2016; 14: 832-5.
3. Isbary G, et al. Penile lentigo (genital mucosal macule) following annular lichen planus: A possible association? Australas J Dermatol 2014; 55: 159-61.
4. El Shabrawi L, et al. Genital lentigines and melanocytic nevi with superimposed lichen sclerosus: A diagnostic challenge. J Am Acad Dermatol 2004; 50: 690-4.
5. Haugh AM, et al. A clinical, histologic, and follow-up study of genital melanosis in men and women. J Am Acad Dermatol 2017; 76: 836-40.
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