Oral Medicine, Oral Pathology and Oral Diagnosis
This domain tests whether you can take a focused history, examine the mucosa and jaws systematically, build a defensible differential and decide when to biopsy, image or refer.
Non-negotiable rules
- Any oral ulcer persisting beyond two weeks without an identifiable cause must be biopsied or referred.
- Leukoplakia and erythroplakia are clinical descriptions, never histological diagnoses. Erythroplakia carries the highest malignant transformation risk among oral potentially malignant disorders; proliferative verrucous leukoplakia transforms frequently despite bland initial histology.
Immunologically mediated disease
- Pemphigus vulgaris: suprabasal acantholysis, IgG against desmoglein 3 and 1, intercellular chicken-wire pattern on direct immunofluorescence, positive Nikolsky sign.
- Mucous membrane pemphigoid: subepithelial split, linear IgG and C3 at the basement membrane zone, desquamative gingivitis; ocular involvement mandates urgent ophthalmology referral.
- Oral lichen planus: bilateral reticular Wickham striae on the buccal mucosa; treat only symptomatic erosive disease.
Neuralgic pain
Trigeminal neuralgia is lancinating and electric, triggered by touch, chewing or cold air. Carbamazepine is first-line; young patients need MRI to exclude a secondary cause such as a cerebellopontine angle mass.
Worked example
A 58-year-old smoker presents with a five-week non-healing ulcer on the lateral border of the tongue; it is indurated, fixed to deep tissue, and a 2 cm firm submandibular node is palpable. The leading diagnosis is squamous cell carcinoma. Correct action: urgent incisional biopsy at the periphery including normal tissue, neck imaging, staging by TNM eighth edition and multidisciplinary referral. The distractor is antifungal or antibiotic therapy with review in two weeks.
Traps
- Treating an erythroplakic patch empirically and losing eight weeks.
- Calling a fibrous lump a diagnosis without histology.
- Missing medication-related osteonecrosis in a patient on denosumab or zoledronate.
- Reassuring the patient because the lesion is painless.