File:Atypical Mitosis.jpg
Micrograph of gastric mucosa with high grade dysplasia. H&E stain.
Three clearly identifiable mitoses are seen. The one at the 12:00 o'clock position is tripolar, i.e. atypical. The mitoses at 3:00 o'clock and 6:00 o'clock are normal. Acute (neutrophils) and chronic (plasma cells, lymphocytes) inflammatory cells are in the lamina propria immediately underneath of the dysplastic epithelium.
Atypical mitoses are a characteristic of precancerous lesions, i.e. dysplasia, and malignancy, i.e. cancer.