In the oral cavity, chewing tobacco predisposes to the squamous cell carcinoma. Grossly, the tumor appears as a red scaling plaque, nodule, or ulcer. The lesion may be associated with hyperkeratosis which in the oral cavity appears as white plaques called leukoplakia. The invasive lesions are composed of islands of squamous cells which in well differentiated carcinomas show keratin pearls. Keratin pearls are ball-like structures made of flattened keratinized cells.
Squmous cells form intercellular bridges.