The diagnostic concordance of actinic keratosis and squamous cell carcinoma

Diagnostic concordance of intraepithelial malignancy is generally only fair. B ecause the diagnosis of actinic keratosis (AK) and squamous cell carcinoma (SCC) is not uniform and because such terms are not consonant with the nomenclature o f other human epithelial malignancies, nomenclature revisions have been attempte d. One hundred dermatopathologists were solicited to review 15 tissue sections r epresenting a spectrum of varying thickness epidermal malignancy and to choose e ither AK or SCC as the diagnosis. Among the 77 participating dermatopathologists , intraclass correlation was high for what was perceived as AK, SCC, and their d ifferentiation. Development of a two-tiered diagnostic system that retains our present diagnostic capabilities, but better fits the pathobiology of superficial epidermal malignancy is suggested.