Basal Cell and Cutaneous Squamous Cell Carcinomas: Diagnosis and Treatment

Keratinocyte carcinoma, traditionally referred to as nonmelanoma skin cancer, includes basal cell and cutaneous squamous cell carcinoma and is the most common skin cancer malignancy found in humans. The U.S. Preventive Services Task Force recommends counseling about minimizing exposure to ultraviolet radiation for people aged six months to 24 years with fair skin types to decrease their risk of skin cancer. Routine screening for skin cancer is controversial. The U.S. Preventive Services Task Force concludes that current evidence is insufficient to assess the balance of benefits and harms of a routine whole-body skin examination to screen for skin cancer. Basal cell carcinoma commonly appears as a shiny, pearly papule with a smooth surface, rolled borders, and arborizing telangiectatic surface vessels. Cutaneous squamous cell carcinoma commonly appears as a firm, smooth, or hyperkeratotic papule or plaque, and may have central ulceration. Initial tissue sampling for diagnosis is a shave technique if the lesion is raised, or a punch biopsy of the most abnormal-appearing area of skin. High-risk factors for recurrence and metastasis include prior tumors, ill-defined borders, aggressive histologic patterns, and perineural invasion. Mohs micrographic surgery has the lowest recurrence rate among treatments but is best considered for large, high-risk tumors or tumors in sensitive anatomic locations. Smaller, lower-risk tumors are treated with surgical excision, electrodesiccation and curettage, or cryotherapy. Topical imiquimod and fluorouracil are also treatment options for superficial basal cell carcinoma and squamous cell carcinoma in situ. There are no clear guidelines for follow up after an index keratinocyte carcinoma, but monitoring for recurrence is important because the five-year risk of subsequent skin cancer is 41%. After more than one diagnosis, the five-year risk increases to 82%. Copyright (C) 2020 American Academy of Family Physicians.