Oral Pathology and Oral Medicine
What this domain tests
Recognition of mucosal and jaw lesions, the clinical reasoning that separates innocent from sinister, and the medical management of oral manifestations of systemic disease.
Core rules
- Leukoplakia and erythroplakia are clinical diagnoses of exclusion - they cannot be diagnosed until other causes (friction, candidosis, lichenoid reaction) are removed and, ideally, histopathology is obtained.
- Red lesions carry a higher risk of dysplasia than white ones; erythroplakia has the highest malignant transformation rate of the two.
- Any ulcer persisting beyond three weeks without a clear cause must be biopsied - the classic trap in oral medicine.
- Oral submucous fibrosis presents with burning, blanching, fibrous bands and progressive trismus; areca (paan) is the key risk factor.
- Odontogenic cysts: radicular (inflammatory, commonest, non-vital tooth), dentigerous (around crown of unerupted tooth), odontogenic keratocyst (parakeratinised, high recurrence, associated with PTCH1).
- Ameloblastoma: locally aggressive, multilocular "soap-bubble" radiolucency in the posterior mandible, requires resection with margins.
Worked example
A 52-year-old tobacco chewer has a painless 1.5 cm ulcer on the lateral border of the tongue for six weeks, indurated, fixed to deep tissue, with a firm submandibular node. Reasoning: duration beyond three weeks, induration, fixation and ipsilateral lymphadenopathy all point to squamous cell carcinoma. The correct next step is an incisional biopsy from the active edge, not a course of antibiotics. TNM staging follows, and treatment is multidisciplinary.
Traps
- Prescribing antimicrobials for a persistent ulcer "to see if it settles".
- Confusing pemphigus vulgaris (intraepithelial, flaccid bullae, positive Nikolsky, desmoglein antibodies) with mucous membrane pemphigoid (subepithelial, tense bullae, basement membrane).
- Calling a keratocyst a "simple cyst" - it recurs and needs long follow-up.