Oral Medicine Diagnosis and Assessment
Domain 1 tests whether you can turn a patient's story into a defensible differential diagnosis and a diagnostic plan. Questions emphasize the order of assessment, the meaning of test results, and the decision to biopsy, image, or refer rather than a memorized disease list.
History as a diagnostic instrument
- Record the chief complaint in the patient's words, then define onset, duration, course, and severity.
- HPI: location, quality, timing, triggers, relieving factors, associated symptoms, and functional impact.
- PMH, all medications including OTC and herbal products, allergies, tobacco/alcohol/betel use, sexual history when relevant, family history, and a focused review of systems.
- Red flags: weight loss, dysphagia, odynophagia, unilateral sensory loss, persistent ulcer beyond two weeks, induration, fixed cervical node, night pain, and trismus.
Examination and tests
- Extraoral: cranial nerves V, VII, IX, XII, cervical lymph nodes, TMJ, salivary glands, and skin.
- Intraoral: mucosal mapping, bimanual palpation, dental and periodontal status, tongue mobility, and denture fit.
- Biopsy: incisional for large or erosive lesions; excisional for small discrete lesions; avoid necrotic centers; include adjacent normal tissue. Send tissue for histopathology and direct immunofluorescence when vesiculobullous disease is possible.
- Laboratory: CBC, ferritin, B12, folate, glucose or HbA1c, HIV, HCV, ANA, anti-Ro/La, serum immunoglobulins, and cultures as indicated.
- Imaging: CBCT for bone, MRI for soft tissue and glands, ultrasound for salivary glands and lymph nodes.
Diagnostic reasoning
- Sensitivity is the proportion of diseased patients who test positive; specificity is the proportion of non-diseased who test negative. Positive predictive value falls when prevalence is low, so a positive test in a rare disease still requires confirmation.
- Use a structured differential such as VINDICATE (vascular, infectious, neoplastic, degenerative, iatrogenic, congenital, autoimmune, traumatic, endocrine).
Worked example
A 54-year-old woman reports burning tongue for six months. Ask about antidepressants, ACE inhibitors, diuretics, dry mouth, taste change, denture wear, and alcohol. Examine for erythematous candidiasis, median rhomboid glossitis, angular cheilitis, and mucosal atrophy. Order fasting glucose, CBC, ferritin, B12, folate, and a candidal smear; add HIV and HCV testing if risk factors exist. A diagnosis of burning mouth syndrome is made only after these causes are excluded. The reasoning is sequential: identify local and systemic causes, treat reversible factors, then reassess.
Traps that cost marks
- Anchoring on candidiasis without checking medications or glucose.
- Labeling burning mouth syndrome before excluding nutritional, infectious, and endocrine causes.
- Not biopsying a chronic ulcer because it looks benign.
- Interpreting a positive test without considering prevalence.
- Omitting sexual history and HIV risk assessment.