Isolated scaly patches may represent actinic (solar) keratoses, nonpigmented seborrheic keratoses, or Bowen or Paget disease.
Actinic keratoses are small (0.2–0.6 cm) macules or papules—flesh-colored, pink, or slightly hyperpigmented—that feel like sandpaper and are tender to palpation. They occur on sun-exposed parts of the body in persons of fair complexion. Actinic keratoses are considered premalignant, but only 1:1000 lesions per year progress to become squamous cell carcinomas.
Application of liquid nitrogen is a rapid method of eradication. The lesions crust and disappear in 10–14 days. “Field treatment” with a topical agent to the anatomic area where the actinic keratoses are most prevalent (eg, forehead, dorsal hands, etc) can be considered in patients with multiple lesions in one region. The topical agents used for field treatment include fluorouracil, imiquimod, and ingenol mebutate. Photodynamic therapy can be effective in cases refractory to topical treatment. Any lesions that persist should be evaluated for possible biopsy.
et al. New and current preventive treatment options in actinic keratosis. J Eur Acad Dermatol Venereol. 2017 Sep;31(Suppl 5):13–7.
et al. Current perspective on actinic keratosis: a review. Br J Dermatol. 2017 Aug;177(2):350–8.
et al. Evidence- and consensus-based (S3) guidelines for the treatment of actinic keratosis—International League of Dermatological Societies in cooperation with the European Dermatology Forum—short version. J Eur Acad Dermatol Venereol. 2015 Nov;29(11):2069–79.
2. Bowen Disease & Paget Disease
Bowen disease (intraepidermal squamous cell carcinoma) can develop on both sun-exposed and non–sun-exposed skin. The lesion is usually a small (0.5–3 cm), well-demarcated, slightly raised, pink to red, scaly plaque and may resemble psoriasis or a large actinic keratosis (eFigure 6–42). These lesions may progress to invasive squamous cell carcinoma. Excision or other definitive treatment is indicated.
This isolated, scaly patch on a patient’s arm turned out to be Bowen disease (intraepidermal squamous cell carcinoma) on biopsy. (Used, with permission, from S Goldstein, MD.)
Extramammary Paget disease, a manifestation of intraepidermal carcinoma or underlying genitourinary or gastrointestinal cancer, resembles chronic eczema and usually involves apocrine areas such as the genitalia. Mammary Paget disease of the nipple, a unilateral or rarely bilateral red scaling plaque that may ooze, is associated with an underlying intraductal mammary carcinoma (Figure 17–4). While these lesions appear as red patches and plaques in fair-skinned persons, in darker-skinned individuals, hyperpigmentation may be prominent.
et al. Risk stratification in extramammary Paget disease. Clin Exp Dermatol. 2015 Jul;40(5):473–8.
et al. Interventions for the treatment of Paget’s disease of the vulva. Cochrane Database Syst Rev. 2013 Oct 26;10:CD009245.