Well-circumscribed deeply pigmented plaque on scrotum.
A 76-year-old man is referred by his family practitioner for evaluation of a concerning growth on his scrotum. According to the patient, the lesion has been present for “quite some time” and has never bled or itched. The patient denies prior history of skin cancer but has previously had several itchy moles removed from his back. Physical examination reveals a well-circumscribed deeply pigmented plaque.
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Seborrheic keratoses are among the most commonly encountered skin growths, with over 83 million Americans believed to be affected by the condition.1 These benign lesions are usually found on the trunk and forehead and may attain a size of >3 cm, with pigmentation ranging from flesh-colored to brown to black. The majority of lesions are asymptomatic; however, pruritus and inflammation are not uncommon, especially when lesions are irritated by clothing.
A genetic predisposition to seborrheic keratosis is well-documented and ultraviolet light exposure may be a contributing factor, although many lesions, including the one in this case, occur at sites that have received minimal or no sun exposure. Genital warts is a usual characteristic of human papillomavirus (HPV) and, although postulated, HPV etiology has not been verified in non-genital seborrheic keratoses.2
Most seborrheic keratoses are readily diagnosed by visual inspection. Dermascopic findings include comedo-like openings and milia-like cysts, which help distinguish it from melanoma.3 Histology has defined 6 subtypes, including hyperkeratotic, acantholytic, reticular/adenoid, clonal, irritated, and melanoakanthoma types.4 Biopsy may be prudent to rule out malignancies such as basal cell carcinoma, squamous cell carcinoma, and melanoma.5 For removal, cryosurgery and curettage are commonly used.
Stephen Schleicher, MD, is director of the DermDox Center for Dermatology, associate professor of medicine at Commonwealth Medical College, and clinical instructor of dermatology at Arcadia University and Kings College.
1. Jackson JM, Alexis A, Berman B, Berson DS, Taylor S, Weiss JS. Current understanding of seborrheic keratosis: prevalence, etiology, clinical presentation, diagnosis, and management. J Drugs Dermatol. 2015;14(10):1119-1125.
2. Kambiz KH, Kaveh D, Maede D, et al. Human papillomavirus deoxyribonucleic acid may not be detected in non-genital benign papillomatous skin lesions by polymerase chain reaction. Indian J Dermatol. 2014;59(4):334-338.
3. Minagawa A. Dermoscopy-pathology relationship in seborrheic keratosis. J Dermatol. 2017;44(5):518-524.
4. Wollina U. Seborrheic keratoses – the most common benign skin tumor of humans. Clinical presentation and an update on pathogenesis and treatment options. Open Access Maced J Med Sci. 2018;6(11):2270-2275.
5. Chen TY, Morrison AO, Cockerell C. Cutaneous malignancies simulating seborrheic keratoses: an underappreciated phenomenon? J Cutan Pathol. 2017;44(9):747-748.