Pathology of lips, oral cavity and pharynx

A) Malformations

Cleft lip (cheiloschisis)

• Failure of fusion of the nasal prominence with the maxillary prominence (primary palate) → split in the upper lip
• Partial/incomplete or complete (extends into nose); unilateral or bilateral

Cleft palate (palatoschisis)

• Failure of fusion of lateral/median palatine processes and nasal septum (secondary palate) → roof of mouth not completely joined; usually with a cleft lip; uvula also split
• Complete (gap in jaw) or incomplete (“hole” in roof of mouth)

Cheilognathopalatoschisis: combination of cleft lip + cleft palate

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B) Ulcerative and Inflammatory Lesions

Dental Caries (tooth decay)

• Cavities where dental plaques accumulate (pits/fissures, cervical tooth, interdental surfaces)
• Dental plaque: sticky biofilm of food debris (sugar), desquamated epithelial cells, salivary glycoproteins, bacteria
• S. mutans ferments sugar → lactic acid → progressive dissolution of enamel and dentine minerals
• Early complications: acute purulent pulpitis (severe toothache), pulp necrosis, tooth loss, apical abscess, subperiosteal abscess, drainage through oral mucosa (“gumboli”)
• Late complications:
  • Periapical granuloma: necrotic tissue at apex of root canal, surrounded by granulation tissue with lymphocytes/plasma cells
  • Radicular cyst: cystic degeneration and epithelialization of the granuloma

Stomatitis

• Inflammation of the mucosal lining of the mouth (cheeks, gums [gingivitis], tongue [glossitis], lips [cheilitis], roof/floor of mouth)
• Causes: poor oral hygiene, infections, mouth burns, poorly fitted dentures

Herpetic Stomatitis

• Caused by HSV-1
• Primary infection: children 6 months – 5 years (infected saliva)
• Latent infection (reactivation): adults exposed to allergies, RTI, pregnancy, menstruation
• Morphology: small vesicles (clear fluid) on/around lips → rupture → shallow, painful ulcers → heal in a few weeks; herpes labialis (cold sore)
• Herpetic gingivostomatitis (children): swollen, tender oral mucosa that bleeds easily; vesicles and bullae ulcerate; abrupt onset, high fever, tender lymph nodes

Oral Candidiasis (Thrush)

• Caused by Candida albicans (normal oral flora)
• Occurs in immunocompromised patients, neonates, patients on broad-spectrum antibiotics
• Morphology: white pseudomembranes on mucosa (fungal hyphae in fibrinopurulent exudate); usually on tongue or inner cheeks; can be scraped off → reveals granular erythematous base

Aphthous Stomatitis (Canker Sores)

• Shallow, small, painful ulcers on movable parts of the mouth
• Morphology: rounded, superficial erosions with grey-white exudate and erythematous rim; on non-keratinized mucosa
• Most common in first two decades of life
• Associated with: emotional stress, fever, certain foods, IBD
• Self-limited (resolve in weeks); may recur

Tonsillitis

• Viral or bacterial inflammation of tonsils; sore throat and fever; peritonsillar abscesses can narrow airways
• Most common: common cold viruses; 2nd: S. pyogenes (bacterial → treat with antibiotics)

Pharyngitis

• Inflammation of the pharynx; pain/sore throat
• Viral: adenovirus, influenza, EBV; Bacterial: S. pyogenes (strep throat), C. diphtheriae (pseudomembrane)

Necrotizing Ulcerative Gingivitis

• Chronic suppurative inflammation of gingival tissue; swollen, erythematous, bleeding gums; periodontal pockets
• Caused by anaerobes (Prevotella intermedia, Fusobacterium) or spirochetes (Borrelia, Treponema)

HIV / Kaposi Sarcoma

• HIV → oral cavity lesions (gingivitis, glossitis)
• Hairy leukoplakia (virtually only in HIV patients): white confluent patches with “hairy” surface (marked epithelial thickening); caused by EBV infection of epithelial cells
• Kaposi sarcoma: >50% of patients develop intraoral purpuric discolorations

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C) Neoplasms

Pre-malignant Lesions

Leukoplakia

• Whitish, well-defined mucosal plaque due to epidermal thickening/hyperkeratosis; cannot be scraped off
• Older men; lower lip vermillion border, buccal mucosa, palate
• Associated with tobacco use (mainly), alcohol, irritants, ill-fitting dentures
• Histology: ranges from banal hyperkeratosis to severe dysplasia/carcinoma in situ
• 3–25% transform to squamous cell carcinoma

Erythroplakia

• Red, velvety, granular, circumscribed areas; may be elevated; poorly defined irregular borders
• Histology: almost always epithelial dysplasia
• Malignant transformation rate >50%

Benign Neoplasms

Papilloma (most common benign oral tumor)

• Soft, pedunculated mass with finger-like projections
• Associated with HPV-6 and HPV-11
• Treatment: surgical removal

Fibromas

• Submucosal nodular fibrous masses from chronic irritation (connective tissue hyperplasia)
• Usually on buccal mucosa along bite line; surgical removal

Pyogenic Granulomas

• Erythematous (red-purple) hemorrhagic mass → ulcerates
• Gingiva of children, young adults, pregnant women
• Histology: dense proliferation of immature vessels (granulation tissue-like)
• Can regress, become fibrous, or develop into peripheral ossifying fibromas

Malignant Neoplasms

Squamous Cell Carcinoma (majority of oral cavity cancers)

• Sites: floor of mouth, ventral/base of tongue, soft palate, gingiva, lower lip
• Causes: (1) cigarette smoking + alcohol; (2) HPV-16/18
• Overall 5-year survival <50%
• Lip cancer has the best 5-year survival rate
• HPV-positive tumors respond better to chemotherapy
• Morphology:
  • Develops from dysplastic precursor lesions
  • Early: raised, firm, pearly plaques or irregular verrucal thickenings
  • Advanced: ulcerated
  • Lymphatic metastases: submandibular + cervical LN
  • Non-keratinizing SCC → HPV-16
  • Keratinizing SCC → smoking + alcohol
• HPV-associated oropharyngeal carcinoma: HPV-16/18; young patients; non-keratinizing/basaloid; generally good prognosis

💡 High-yield: Dental caries = S. mutans + lactic acid. Thrush = Candida; white pseudomembrane scraped off. Hairy leukoplakia = EBV; HIV patients. Leukoplakia = cannot scrape off; 3–25% SCC. Erythroplakia = red; >50% malignant. Oral SCC = smoking/alcohol or HPV-16; lip = best prognosis; non-keratinizing = HPV; keratinizing = smoking.