Basal Cell and Cutaneous Squamous Cell Carcinomas: Diagnosis and Treatment


Am Fam Physician. 2020 Sep 15;102(6):339-346.

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Related editorial: Keratinocyte Carcinomas: Should We Screen for Them?

Author disclosure: No relevant financial affiliations.

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%.

Keratinocyte carcinoma, referred to as nonmelanoma skin cancer, comprises basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (CSCC). BCC is the most common skin cancer malignancy and affects more than 3.3 million people annually in the United States.1 CSCC is the second most common skin cancer, with up to 400,000 U.S. cases and more than 3,000 disease-related deaths annually.2 Lifetime risk of keratinocyte carcinoma in the United States is at least 20% and is greater than 30% for White patients.3

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Clinical recommendationEvidence ratingComments

Basal cell carcinoma and cutaneous squamous cell carcinoma should be primarily treated with surgical excision.1


Expert consensus

High-risk tumors and tumors with more invasive histologic subtypes (micronodular, infiltrative, and morpheaform) are best treated with Mohs micrographic surgery.22


Randomized trial comparing outcomes with standard excision to Mohs micrographic surgery

Excision of basal cell carcinoma with pathology demonstrating tumor at the surgical margin, should be followed by immediate reexcision or Mohs micrographic surgery.24


Diagnostic cohort study evaluating tumor recurrence after incomplete excision

Cryotherapy should be considered for low-risk lesions only when more effective therapies are contraindicated or impractical.1,2


Clinical guideline from specialty society

Superficial basal cell carcinoma in low-risk sites may be treated with topical 5% imiquimod (Aldara) or 5% fluorouracil.1


Clinical guideline from the American Academy of Dermatology

A = consistent, good-quality patient-oriented evidence; B = inconsistent or limited-quality patient-oriented evidence; C = consensus, disease-oriented evidence, usual practice, expert opinion, or case series. For information about the SORT evidence rating system, go to

The Author

JONATHON M. FIRNHABER, MD, MAEd, MBA, FAAFP, is vice chair of Academic Affairs, associate professor, and residency program director in the Department of Family Medicine at the Brody School of Medicine at East Carolina University, Greenville, N.C.

Address correspondence to Jonathon M. Firnhaber, MD, MAEd, MBA, East Carolina University, Family Medicine Center, 101 Heart Dr., Greenville, NC 27834 (email: Reprints are not available from the author.

Author disclosure: No relevant financial affiliations.


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