In an important article (Diesner et al., 2021), photos are shown that include correctly labeled seborrheic keratoses (SKs). However, the captions indicate that SKs are “a sign of a lifetime of skin damage from ultraviolet radiation.” I believe that is inaccurate.
SKs appear mainly on the face and the “seborrheic areas” (the inaccurate source of their name—they are unrelated to seborrhea or sebaceous glands) of the trunk. The latter is a typically covered area. In fact, SKs are common on the “doubly covered” buttocks and pubic areas. They are less common on often exposed arms and legs and are not seen only on the palms and soles (Domonkos, 1971; Koh, 1975).
Furthermore, “Neither painful sunburns nor lifetime sun exposure were associated with an increased risk of seborrheic warts” (Kennedy et al., 2003). The American Academy of Dermatology notes: “You can find these harmless growths anywhere on the skin, except the palms and soles. Most often, you'll see them on the chest, back, head, or neck” (www.aad.org [https://www.aad.org/public/diseases/a-z/seborrheic-keratoses-overview, 2021]).
Now, because medicine is an inexact science, the following should be noted. Some mutations found in SKs (e.g., FRFR3) are associated with an increased age and location on the head and neck, suggesting a role of ultraviolet radiation in their origin (Hafner et al., 2007). In a related study, “Seborrheic keratoses are common in the Korean males…. Both aging and cumulative sunlight exposure were found to be independent contributory factors” (Kwon et al., 2003). Finally, “Exposure to sunlight has been suggested to play a role in the development of lesions in those predisposed to develop SKs” (Chung, 2003). Please note that these latter two studies are limited to Asian patients. More to the point, none of these articles refers to SKs as “damaged skin.”
Further adding to the ambiguity, studies have shown more frequent occurrence and earlier age of onset in those residing in tropical climates as well as a higher prevalence of SKs on sun-exposed areas in those subjects (Bolognia et al., 2012). In a study of truckers, SKs were more common in areas of sun exposure, specifically the driver's side (James et al., 2011).
Nevertheless, for most of the patients whom we see, SKs are completely benign (if unsightly); I am not sure if it is fair to say they are “indicative of sun damage.” This may cause unnecessary worry for patients who have them, apart from their appearance concerns. Most insurances will not cover removal of noninflamed SKs, as they consider this a cosmetic procedure.
On an additional note, Diesner et al. refer to the “classic ugly duckling” appearance of melanoma (Diesner et al., 2021). This term does not denote the “unattractive” appearance of many melanomas, but to the fact that, in a patient with multiple pigmented papules, it is sometimes the one that does not look like all of the others and stands out, even if it itself appears benign, that might bear further investigation. In other words, one cannot use that term referring to a solitary lesion—it must be in the context of one lesion being noticeably different from the rest in a large field (Grob & Bonerandi, 1998).
Manfred S. Rothstein, MD, FAAD, FACP
Department of Dermatology
Duke University Medical School
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