The diagnostic concordance of actinic keratosis and squamous cell carcinoma.

Diagnostic concordance of intraepithelial malignancy is generally only fair. Because the diagnosis of actinic keratosis (AK) and squamous cell carcinoma (SCC) is not uniform and because such terms are not consonant with the nomenclature of other human epithelial malignancies, nomenclature revisions have been attempted. One hundred dermatopathologists were solicited to review 15 tissue sections representing a spectrum of varying thickness epidermal malignancy and to choose either AK or SCC as the diagnosis. Among the 77 participating dermatopathologists, intraclass correlation was high for what was perceived as AK, SCC, and their differentiation. Development of a two-tiered diagnostic system that retains our present diagnostic capabilities, but better fits the pathobiology of superficial epidermal malignancy is suggested. Davis DA, Donahue JP, Bost JE, Horn TD. The diagnostic concordance of actinic keratosis and squamous cell carcinoma.