At high magnification, this squamous cell carcinoma demonstrates enough differentiation to tell that the cells are of squamous origin. The cells are pink and polygonal in shape with intercellular bridges (seen as desmosomes or "tight junctions" by electron microscopy). However, the neoplastic cells show pleomorphism, with hyperchromatic nuclei. A mitotic figure is present near the center.
What is the significance of mitotic figures in a neoplasm? In general, their appearance suggests a higher rate of cellular proliferation. Mitoses certainly are present in normal tissues (surface epithelia are constantly regenerating, and hematopoiesis produces billions of new blood cells each day). However, the presence of mitoses, and particularly abnormal mitoses, in a mass lesion supports a diagnosis of neoplasia, and likely a malignant neoplasm.