Fig. 1

(a) Negative for tumor cells. Normal superficial and intermediate squamous cells. The background is completely clear. All nuclei are round to ovoid with smooth contours and finely granular, evenly dispersed chromatin. (b) Doubtful for tumor cells. Sheets of atypical squamous cells. The nuclei are haphazardly oriented, and the axes of different nuclei are not parallel. Orangeophilic cells represent abnormal variations in nuclear size and hyperchromasia. (c) Positive for tumor cells. A loosely cohesive sheet of highly atypical, immature basal, or para-basal-like squamous cells. The nuclear-to-cytoplasmic ratio is markedly increased. Nuclei are highly hyperchromatic and chromatin is coarse. Some cells show an irregular nuclear contour and/or small nucleoli. Some bizarre orangeophilic cells represent atypical keratinization. Those cells may have opaque, nearly black nuclei with smudged chromatin