[Actinic keratosis and development of cutaneous squamous cell carcinoma]

Actinic keratosis is a common sun-induced skin disease. For many years there has been a great deal of discussion of the term used for the disease and of its classification. Recent molecular studies indicate an association between actinic keratosis and squamous cell carcinoma.

Review of recent reports on histological, molecular, biochemical and clinical findings in actinic keratosis and cutaneous squamous cell carcinoma.

The morphology of atypical cells in both actinic keratosis and squamous cell carcinoma is identical. The risk of progression to squamous cell carcinoma is minimal, but up to 60% of squamous cell carcinoma cases begin as actinic keratosis. Regression of actinic keratosis occurs when sun exposure is decreased. Examination of possible chromosome aberrations and gene mutations in both actinic keratosis and squamous cell carcinoma reveals similar patterns, including the same mutation in the tumour suppressor gene TP53. Recent studies indicate that actinic keratosis is the earliest manifestation of a potentially malignant disease similar to carcinoma in situ in cervix uteri. Thus, actinic keratosis requires careful diagnosis and follow up.