Squamous cell carcinoma in situ

The term Bowen disease refers to squamous cell carcinoma in situ of the skin. These lesions typically appear as elevated, nonhealing, erythematous lesions. They may present with scaling, crusting, or pigmented keratotic plaques. Pathologically, the lesions demonstrate full-thickness epidermal atypia without dermal invasion, in contrast to the partial thickness atypia of actinic keratoses. In 5% of patients, Bowen disease may progress to vertically invasive squamous cell carcinoma; therefore, complete surgical excision is advised. Alternatively, electrodessication and curettage, cryotherapy, and 5-fluorouracil may be used, especially in larger areas of involvement.

Keratoacanthoma

Although keratoacanthoma was formerly considered to be a benign lesion, many authors now regard this entity as a low-grade squamous cell carcinoma. The lesion usually begins as a flesh-colored papule on the lower eyelid that develops rapidly into a dome-shaped nodule with a central keratin-filled crater and elevated rolled margins (Fig 10-45). Keratoacanthomas typically occur in middle-aged and elderly individuals, and there is an increased incidence in immunosuppressed patients. Gradual involution over the course of 3–6 months has often been observed. The abundant keratin production in the center of the lesion may incite a surrounding inflammatory reaction, which may play a role in ultimate resolution. At present, incisional biopsy followed by complete surgical excision is recommended. Intralesional methotrexate or 5-fluorouracil may be options for patients who are not surgical candidates.

Figure 10-45 Keratoacanthoma.

Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.