Oral Medicine and Oral Diagnosis
Oral medicine rewards systematic pattern recognition: site, duration, symmetry, and whether skin or systemic involvement is present.
Ulcerative disease
- Recurrent aphthous stomatitis is the most common ulcerative disease of the mouth; minor ulcers under 1 cm healing in 7-10 days far outnumber major and herpetiform types.
- A single, indurated, painless ulcer lasting over three weeks is carcinoma until biopsied.
- Behcet disease combines oral and genital ulcers with uveitis.
- Necrotising sialometaplasia on the palate mimics malignancy histologically.
Vesiculobullous and immune disease
- Pemphigus vulgaris: flaccid blisters, positive Nikolsky sign, suprabasal acantholysis, intercellular IgG, anti-desmoglein 3; managed with systemic steroids.
- Mucous membrane pemphigoid: desquamative gingivitis, subepithelial split, linear IgG/C3; ocular and laryngeal scarring changes urgency.
- Oral lichen planus: bilateral reticular striae, band-like lymphocytic infiltrate at the interface, saw-tooth rete pegs; persistent erosive lesions should be biopsied for transformation risk.
Systemic and pain conditions
- MRONJ: AAOMS stages 0-3; risk rises with zoledronic acid and denosumab, and after extraction.
- Trigeminal neuralgia: sharp electric pain in V2 or V3 with trigger zones; carbamazepine first line; imaging excludes compression or demyelination.
- Diabetes and leukaemia present with gingival bleeding or enlargement; HIV with Kaposi sarcoma and hairy leukoplakia.
Worked example
A 52-year-old woman has desquamative gingivitis, erosions on both buccal mucosae and a positive Nikolsky sign without skin lesions. Nikolsky with erosions favours pemphigus over lichen planus; perilesional direct immunofluorescence showing intercellular IgG confirms pemphigus vulgaris. She needs dermatology referral and systemic therapy, not topical steroid alone.
Traps
Applying Nikolsky to every blistering disease; treating a chronic ulcer with mouthwash instead of biopsying; missing erythematous candidiasis because it is painless; diagnosing erosive lichen planus without histology.