Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)To evaluate comparatively the influence of histopathological features on epithelial dysplasia (ED) and the effectiveness in usage of WHO and binary grading systems in actinic cheilitis (AC). Material and methodsCytological and architectural alterations established by WHO for ED were evaluated in 107 cases of AC. Epithelial dysplasia was graded using WHO and binary systems. The comparisons were performed using kappa, chi-square, and phi coefficient tests (P<0.05). ResultsMost cases were classified as mild ED (44.5%) in the WHO system and as low risk for malignant transformation (64.5%) in the binary system. There was a positive correlation between WHO and binary systems (k=0.33; P<0.0002). Loss of basal cell polarity (P<0.001) was associated with severity of ED grade in the WHO system. Anisonucleosis (P<0.0001), nuclear pleomorphism (P<0.0001), anisocytosis (P=0.03), cell pleomorphism (P=0.002) increased nuclear/cytoplasm ratio (P<0.0001), increased nuclear size (P<0.0001), increased number of mitotic figures (P=0.0006), and dyskeratosis (P=0.008) were associated with severity of ED grade in the binary system. ConclusionsIt seems that usage of binary ED grading system in AC may be more precise because there is correlation between many of cytological and some of architectural microscopic alterations with increased grade of ED.226523529Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)Fundacao Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro (FAPERJ)Pro-Reitoria de Pesquisa e Inovacao da Universidade Federal Fluminense (PROPPI-UFF), BrazilConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)