Actinic keratosis is an early in situ squamous cell carcinoma: a proposal for reclassification

TLDR

Actinic keratosis is a sun‑induced, erythematous, scaly lesion whose histology aligns with squamous cell carcinoma in situ, yet no consensus exists on its classification. The authors propose reclassifying actinic keratosis as early in situ squamous cell carcinoma to improve diagnostic clarity and treatment guidance. They introduce a three‑tier system—early in situ SCC Type AK I, Type AK II, and Type AK III—to reflect increasing histopathologic severity.

Abstract

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. Consequently, several classification systems for AK have been suggested, but as yet no consensus has been reached. These systems strive to correlate the pathological and clinical features to better provide physicians 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.