Diagnosis
Diagnosis is primarily clinical — there is no specific diagnostic test for RAS. Based on characteristic appearance, location (non-keratinized mucosa), and recurrent pattern.
Key differentiating feature from herpes: aphthous ulcers occur on non-keratinized mucosa only; herpes simplex recurrences (oral herpes) occur on keratinized mucosa (hard palate, gingiva, dorsal tongue) and on the lips. Primary herpetic gingivostomatitis causes systemic symptoms, fever, and generalized gingival involvement.
Blood tests to identify predisposing deficiencies: full blood count (anemia), serum iron/ferritin, folate, vitamin B12, zinc levels, anti-tissue transglutaminase antibodies (celiac screen) for patients with frequent recurrences.
Consider Behçet's disease if genital ulcers or uveitis are also present — refer to rheumatology.
Biopsy is NOT routinely indicated but should be performed for ulcers lasting >3 weeks, single persistent ulcers, or atypical presentations to exclude malignancy.