• actinic keratosis;
  • cell carcinoma;
  • in situ;
  • reclassification;
  • squamous

Summary The term actinic keratosis (AK) describes a sun-induced, clinical erythematous lesion covered with scale, but does not provide an understanding of the biology or histopathology of the lesion. Cousequeutly, several classification systems for AK have been suggested, but as yet no cousensus has been reached. These systems strive to correlate the pathological and clinical features to better provide physcians with the most accurate information to enable correct decisions to be made regarding treatments, Prognosis and metastatic potential. AK is a clinical description that has a histological diagnosis consistent with squamous cell carcinoma (SCC) in situ. We recommend an AK classification system that describes these lesions as squamous cell carcinomas (SCCs), using the terminology ‘early in situ SCC Type AK I’, ‘early in situ SCC type AK II’ and ‘in situ SCC Type AK III’, there by giving clinicians better guidance for diagnosis and specific treatment recommendations.