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Common Cutaneous Malignancies

»	How are skin cancers classified?
»	What are the most common nonmelanoma skin cancers (NMSCs)?
»	What is the most important cause of NMSC?
»	Are there any other causes of NMSC?
»	What special populations are at increased risk of NMSC?
»	How are NMSCs diagnosed?
»	How frequently do NMSCs occur?
»	How can NMSCs be prevented?
»	What factors should you consider in treating NMSC?
»	What are basal cell carcinomas?
»	What is the molecular basis for the development of sporadic basal cell carcinoma?
»	Describe the clinical and histologic appearance of basal cell carcinomas.
»	What is nevoid basal cell carcinoma syndrome?
»	What do typical squamous cell carcinomas look like clinically?
»	What is the biologic behavior of cutaneous squamous cell carcinoma?
»	What are keratoacanthomas?
»	How do keratoacanthomas present clinically?
»	What is Bowen’s disease?
»	What is an actinic keratosis?
»	What do actinic keratoses look like?
»	How should premalignant lesions, such as actinic keratoses and actinic cheilitis, be treated?

What is an actinic keratosis?

Actinic keratoses (solar keratoses) are sun-induced precancerous lesions of the skin. They are very common in patients with light skin color and significant sun exposure. Microscopically, actinic keratoses are characterized by a proliferation of cytologically atypical keratinocytes that bud off or replace the bottom of the epidermis. The atypical cells do not involve the full thickness of the epidermis. A definitive prospective study has never been done, but epidemiologic and retrospective studies suggest that 6% to 20% of actinic keratoses progress into squamous cell carcinomas if left untreated.

Anwar J, Wrong D, Kimyai-Asadi A, Alam M: The development of actinic keratosis into invasive squamous cell carcinoma: evidence and evolving classifications schemes, Clin Dermatol 22:189–196, 2004.