Oral Pathology: Premalignant and Malignant Lesions

Premalignant Oral Lesions

• Erythroplakia:
  • Appearance: Flat, macular red patch.
  • Histology: Severe dysplasia, decreased keratin.
• Carcinoma In Situ:
  • Histology: Intact basement membrane, severe epithelial dysplasia (top and bottom changes).
• Oral Submucous Fibrosis:
  • Appearance: Red patch, ulceration, burning sensation.
  • Histology: Atrophic epithelium, dysplasia.

Malignant Oral Lesions

Squamous Cell Carcinoma (SCC)

• Common Sites: Lower lip, lateral border of tongue, floor of mouth.
• Clinical Forms: Ulcer, exophytic, red/white patches, trismus, bone destruction/pathological fracture, tooth mobility.
• Ulcer Criteria: Indurated base, necrotic floor, everted edges, bleeding, bad odor, firm consistency.
• Histology: Epithelial invasion into connective tissue, abnormal cell forms (dysplasia), chronic inflammation.
• Grading:
  • Well-differentiated (G1): Polyhedral cells with intercellular bridges, abnormal keratinization (keratin plugs).
  • Moderately differentiated (G2): Absent keratin pearls, fewer cell nests.
  • Poorly differentiated (G3, G4): Absent keratin and cell nests, loss of cell cohesion.

Other Malignant Carcinomas

• Spindle Cell Carcinoma: Found on the lower lip. Histology shows sheets of malignant spindle cells (pleomorphic, hyperchromatic, abnormal mitosis), cytokeratin marker positive.
• Verrucous Carcinoma: Associated with HPV 16/18. Exophytic, finger-like projections on buccal mucosa and alveolar ridge. Histology shows keratin plugs and blunt rete pegs (microinvasion).
• Papillary SCC: Associated with HPV 16/18. Found in the larynx and pharynx. Histology shows finger-like projections and epithelial dysplasia.
• Basal Cell Carcinoma: Found on the upper lip (sun-exposed). Histology shows epithelial invasion into connective tissue, stromal retraction, and melanocytes.
• Mucosal Melanoma: Found on gingiva and palate. Histology shows nests of melanocytes in connective tissue with pleomorphism and atypism. Follows ABCDE criteria (Asymmetry, Border, Color, Diameter, Evolving).

Sarcomas

• Fibrosarcoma: Occurs in ages 20–40. Presents as an ulcer with bleeding. Histology shows thin-walled blood vessels and malignant fibroblasts.
• Osteogenic Sarcoma: Found in the mandible, often associated with Paget's disease. Radiographic appearance shows "sun-ray" pattern and ill-defined radiolucency.
• Chondrosarcoma: Affects cartilage (anterior maxilla, posterior mandible). Histology shows increased cell numbers and lacunae containing multiple cells.
• Kaposi Sarcoma: Associated with AIDS and HHV8. Found on the palate and gingiva. Histology shows slit-like vascular spaces and spindle cell proliferation.
• Ewing Sarcoma: Found in the mandible. Radiographic appearance shows "onion-skin" pattern, ill-defined radiolucency, and root resorption. Histology shows round cells and nuclei.