Actinic keratosis (AK) are very common. 30-50% of caucasian population in southern regions are concerned. Modern dermatopathology has decided to classify AK as squamous cell carcinoma in situ (SCCis). It has been estimated that 10% of AK transform into invasive squamous cell carcinoma (invSCC) within 10 years. Despite the relatively low rate of transformation, the burden of invSCC is exceedingly high. Some 2-5% eventually metastasize and can end lethally. For the southern states of the US is has been estimated that the death rate from SCC is almost as high as from melanoma. Medically immunosuppressed patients (organ transplant recipients, patients with autoimmune diseases) and patients with non-Hodgkin lymphoma (NHL), including chronic lymphocytic leukemia (CLL), are particularly prone to AK and invSCC. In NHL/CLL invSCC are more aggressive than in any other setting.
Up today no RCT has shown the reduction of AK transformation to inv SCC by active treatment (vs watchful waiting). Empirically however, proactive removal of AK seems to be particularly justified in immunosuppressed patients, as well as in patients with clinically more advanced, so-called hyperplastic AK.
The traditional modalities of curettage with electrodessication and cryosurgery have been augmented by a variety of topical treatments, such as 5-fluoroucracil, also in combination with salicylic acid, imiquimod and resiquimod, ingenol mebutate and diclofenac. The current lecture gives a brief overview on indications, applications, and available literature.