6-18: Miscellaneous Scaling Dermatoses

Isolated scaly patches may represent actinic (solar) keratoses, nonpigmented seborrheic keratoses, or Bowen or Paget disease.

1. ACTINIC KERATOSES

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 1:1000 lesions per year progress to squamous cell carcinoma.

Application of liquid nitrogen provides rapid eradication of lesions, which crust and disappear in 10–14 days. “Field treatment” with a topical agent to an 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. Fluorouracil cream is the most effective topical agent used for field treatment; imiquimod and ingenol mebutate are also effective, as is photodynamic therapy. Combination therapy may be clinically beneficial. Any lesions that persist should be evaluated for possible biopsy.

2. BOWEN DISEASE & PAGET DISEASE

Bowen disease (intraepidermal squamous cell carcinoma) can develop on 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 6–49). Lesions may progress to invasive squamous cell carcinoma. Excision or other definitive treatment such as topical treatment (fluorouracil or imiquimod) or photodynamic therapy is indicated.

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 (see Figure 17–3). While these lesions appear as red patches and plaques in fair-skinned persons, in darker-skinned individuals, hyperpigmentation may be prominent.