Every dermatologist confronts how to ask a person to disrobe for a full body skin examination. Ultimately, I came up with the following line when asked what should be exposed: “The more of you I see, the better off you are – please get undressed to your level of comfort”. While that works reasonably well, unfortunately the majority of patients will leave their underpants on, unless they were aware of specific lesions of concern.
Regarding perianal nevi, Socik et al, including patients aged 23 to 84 years, studied 236 participating patients. Perianal nevi of any size, at least 2 mm in diameter, and at least 5 mm in diameter were evident in 48.9% (107 of 219), 39.7% (87 of 219), and 5.5% (12 of 219) of non-Hispanic whites, respectively; 50.0% (2 of 4), 0 (0 of 4), and 0 (0 of 4) of Hispanic whites, respectively; and 38.5% (5 of 13), 38.5% (5 of 13), and 0 (0 of 13) of nonwhites, respectively. In non-Hispanic whites, the presence of at least 1 perianal nevus was significantly associated with history of atypical nevus excision (odds ratio [OR], 2.9; 95% CI, 1.5-5.7); and extant findings of at least 1 atypical nevus (OR, 2.2; 95% CI, 1.3-3.9); atypical nevus pattern (≥20 nevi that were ≥2 mm in diameter), plus at least 5 nevi that were 5 mm or greater in diameter (OR, 1.8; 95% CI, 1.1-3.1); and at least 4 atypical nevi 5 mm or greater in diameter (OR, 1.9; 95% CI, 1.1-3.3).The authors concluded that perianal melanocytic nevi were common and were associated with prominent and atypical nevi elsewhere. The perianal area is worthy of attention during melanoma screening and surveillance (1).
Although anorectal melanomas are rare, accounting for approximately 1% of all anorectal carcinomas, the anorectum is the third most common location for melanoma, following cutaneous and ocular sites (2). Based on Socik et al, perhaps a history of atypical nevi increases the risk of perianal melanoma. I surmise that for most people, ultraviolet exposure is unlikely! What about immunosuppression or HIV status? Recently, Olsen et al have demonstrated that patients with HIV/AIDS remain at a significantly increased risk of developing melanoma in the post HAART era (3). Despite this fact, I cannot find any studies to denote an increased risk of perianal melanoma in immunosuppressed patients.
In the HIV population, human papillomavirus (HPV)-induced anogenital lesions are notable in HIV-positive men who have sex with men (MSM). Kreuter et al reported that a high proportion of anogenital warts contained areas of high-grade and low-grade dysplasia or even invasive cancer. Some of these lesions contained only low-risk-HPV types. Interestingly they found that even low-risk HPV types might be capable of inducing high-grade dysplasia in immunosuppressed patients, even in lesions with the clinical appearance of classical anogenital warts. Dysplasia was absent in all lesions of immunocompetent control patients. They recommend that all high risk patients, such as those who are HIV-positive MSM, in addition to HPV vaccination, have such lesions evaluated histopathologically for dysplasia, in order to detect those lesions at risk for the development of anal squamous cell carcinoma (4).
One of the downsides of practicing dermatology is having people (friends, relatives, and strangers) come out of nowhere, showing you their skin lesions, and thereby seeking immediate advice. I would always joke that I should have been a proctologist – nobody shows you their lesions. Clearly, we need to perform perianal exams, especially in those with atypical nevi or immunosuppressed patients, notably MSM who are HIV positive. If we can obviate the ravages of anogenital melanoma or squamous cell carcinoma, our patients’ prognoses will be looking up.
- Socik A, et al. Prevalence and gross morphologic features of perianal melanocytic nevi. JAMA Dermatol 2016; 152; 1209-17.
- Rallis E, Tsibouris P. Pigmented perianal macules. Clin Case Rep 2015; 4: 95-6.
- Olsen CM, et al. Risk of melanoma in people with HIV/AIDS in the pre-and post-HAART eras: A systematic review and meta-analysis of cohort studies. PLoS One 2014; Apr 16; 9 (4): e95096
- Kreuter A, et al. High-grade dysplasia in anogenital warts of HIV-positive men. JAMA Dermatol 2016; 152; 1