Actinic keratoses. Differential diagnosis and treatment.

Actinic keratoses are extremely common premalignant keratinocytic neoplastic lesions that develop primarily in fair-complexioned individuals during midlife or beyond. Genetic, occupational and other environmental factors predispose to the development of these lesions. Without treatment, a significant number may progress to fully developed neoplasms, especially squamous cell carcinoma, over a period of 20 to 50 years. The multistep theory of carcinogenesis is helpful in understanding the pathogenesis and progression of this important and highly prevalent lesion.