Shedding new light on actinic keratoses and squamous cell carcinoma in situ.

Cutaneous squamous cell carcinoma can arise from various premalignant lesions such as actinic keratosis, Bowen disease, and premalignant genital squamous cell lesions. Identification and treatment can prevent malignant transformation and death. This article describes the causes, epidemiology, and characteristics of suspicious premalignant squamous cell lesions so that clinicians can identify these lesions and refer patients for specialist treatment as appropriate.