The most common malignant lesion in the mouth is squamous cell carcinoma (90%). This is often preceded by precursor lesions such as oral leukoplakia. When squamous cell cancer infiltrates deeper in the tissue it has a tendency to spread through lymph- and blood vessels.
There are other less common types of oral cancer such as: adenocarcinoma from minor salivary glands, lymphoma from tonsillar region and melanoma from melanin-producing cells of the oral mucosa.
In oral biopsies the pathologist must evaluate the squamous epithelium:
- atypia and degree of atypia
- carcinoma in situ
- invasive carcinoma
- depth of invasion
When resection of tumor is performed the pathologist should evaluate tumor type, size, depth of invasion, pattern of invasion, vessel invasion, perineural invasion and resection borders.