Incipient intraepidermal cutaneous squamous cell carcinoma: A proposal forreclassifying and grading solar (actinic) keratoses

Actinic keratoses (AKs) are primarily induced by ultraviolet (UV) radiation and are often identified as premalignant lesions, In our opinion, AKs are proliferations of transformed, neoplastic keratinocytes confined to the epi dermis that may eventually extend into the dermis, at which point they are termed squamous cell carcinoma (SCC). In contrast to AKs, SCCs have the pot ential to metastasize and kill. This process is analogous to that of evolvi ng carcinoma of the uterine cervix that has been termed cervical intraepith elial neoplasia (CIN), a time-tested and reliable classification that provi des clinicians with accurate information on which to base treatment decisio ns regarding cervical neoplasms following biopsy testing. A similar classif ication scheme could provide guidance to clinicians for the diagnosis and t reatment of evolving SCC of the skin and as such, we propose a similar clas sification using the terminology keratinocytic intraepidermal neoplasia (KI N). This system is more reflective of the histology and natural history of SCC and eliminates ambiguity in the terminology of lesions currently referr ed to as AKs, The KIN classification defines features by which individual s pecimens can be objectively graded and specific treatment recommendations a re made based on the grade of the lesion, We propose that the term keratino cytic intraepidermal neoplasia (KIN) be used to define and describe evolvin g SCC of the skin and that the term actinic (solar) keratosis be eliminated . Copyright (C) 1999 by W.B. Saunders Company.