Management of Actinic Keratoses and Keratinocyte Carcinomas

Actinic keratoses are precancerous skin lesions that are treated to prevent progression to cutaneous squamous cell carcinoma. Keratinocyte carcinomas include basal cell carcinoma and cutaneous squamous cell carcinoma. Cryosurgery is preferred to treat a single or limited number of actinic keratosis lesions, whereas field-directed therapies, such as topical fluorouracil, topical imiquimod, photodynamic therapy, topical tirbanibulin, and off-label topical fluorouracil plus calcipotriene, are preferred treatments for multiple lesions or significant field cancerization. For basal cell carcinoma, low-risk lesions may be treated with standard surgical excision, electrodesiccation and curettage, or topical agents for superficial subtypes. Basal cell carcinoma that is high risk or in cosmetically or functionally sensitive areas warrant Mohs surgery or similar techniques that provide complete margin assessment. Squamous cell carcinoma in situ can be managed with topical therapies, photodynamic therapy, electrodesiccation and curettage, or Mohs surgery for high-risk sites. Invasive cutaneous squamous cell carcinoma should be treated surgically, typically with 4- to 6-mm margins for low-risk tumors and Mohs surgery for tumors that are high-risk or located in cosmetically or functionally sensitive areas. Radiation is an alternative for patients who are not candidates for surgery. Systemic hedgehog pathway inhibitors are approved for locally advanced or metastatic basal cell carcinoma in patients who are not candidates for surgery or radiation therapy, although adverse effects often limit tolerance. Checkpoint inhibitor immunotherapy can be used in certain advanced cases of basal cell or cutaneous squamous cell carcinoma.