Oral cavity: Lips, gingiva (gums), floor of mouth, buccal mucosa, anterior 2/3 of the tongue, hard palate, retromolar trigoneOropharynx: Soft palate, tonsils, walls of the throat, posterior 1/3 of tongue

Keratinized stratified squamous epithelium: Hard palate, dorsal surface of tongue, gingivaNonkeratinized stratified squamous epithelium: buccal mucosa, floor of the mouth, lateral & ventral surfaces of tongue, soft palate, retromolar trigone

Premalignant changes:- Leukoplakia: White plaque, usually painless, can't be scraped away. Risk factor: Tobacco. - Proliferative verrucous leukoplakia: Affects women, rough white lesions, dysplasia - Erythroleukoplakia: Lesions develop red spots, epithelium becomes atrophic → visible blood vessels (red) → erythroplakiaDD: Frictional keratosis

- Squamous cell carcinoma→ sun exposure, actinic chelitis, tongue, lower lip vermillon- Adenocarcinomas- Extranodal lymphomas- Melanomas

Risk factors: Tobacco smoking, alcohol abuse, UV radiation, exposure to metal dust/chemicals, Plummer-Vinson syndrome, immune deficiencies- Tumors of the oral cavity are not associated with HPV (vs. oropharyngeal cancers)

Diagnosis: Biopsy- Lymph node biopsy + imaging for TNM tumor staging