Oral Pathology and Oral Medicine
Scope
Tests your ability to recognise oral mucosal disease, separate reactive and immune-mediated lesions from malignancy, and identify odontogenic cysts and tumours by site, lining and clinical behaviour.
Potentially malignant disorders
- Leukoplakia is a clinical label of exclusion: a white patch that cannot be attributed to another cause. Non-homogeneous and erythroleukoplakic lesions carry the highest transformation risk.
- Oral submucous fibrosis follows areca nut use and produces fibrous bands with progressive trismus.
- Oral lichen planus shows bilateral white striae on the buccal mucosa; erosive forms need biopsy to exclude dysplasia.
Immune-mediated disease
- Pemphigus vulgaris: IgG against desmoglein 1 and 3, suprabasal acantholysis, intraepithelial split, positive Nikolsky sign.
- Mucous membrane pemphigoid: linear IgG and C3 at the basement membrane, subepithelial split; ocular scarring is the serious complication.
Odontogenic lesions
- Radicular cyst - inflammatory, at the apex of a non-vital tooth, the commonest jaw cyst.
- Dentigerous cyst - encloses the crown of an impacted tooth at the cementoenamel junction.
- Odontogenic keratocyst - thin corrugated lining, satellite cysts, high recurrence, PTCH1 mutation.
- Ameloblastoma - locally aggressive multilocular radiolucency, typically posterior mandible.
Worked example
A 52-year-old smoker has a two-month non-healing ulcer on the lateral border of the tongue, indurated and fixed to the floor of the mouth. Reasoning: an ulcer beyond two weeks with induration rather than tenderness suggests squamous cell carcinoma; lateral tongue and floor of mouth are the commonest sites; the next step is incisional biopsy, not empirical antifungal therapy.
Traps
- Diagnosing leukoplakia without excluding friction, candidosis and lichenoid drug reactions.
- Reversing pemphigus (intraepithelial) and pemphigoid (subepithelial) split levels.