Figure 1. Biopsy of leukoplakia in floor of mouth showing severe dysplasia/carcinoma in situ. Note normal epithelium in left side. The dysplastic area is especially characterized by an increased nuclear-cytoplasmic ratio, an increased number of mitotic figures including abnormal mitoses and mitoses occurring in the middle and upper parts of the epithelium, nuclear hyperchromatism, and enlarged nuclei. H&E, X90.