Oral Pathology
Mucosal lesions are usually identified by three things in this order: color, location, history. The 15 lesions in this chapter cover the vast majority of OSCE photographs — the trick is knowing which one earns a biopsy now.
Malignancy Potential — The Ladder
Sort every lesion onto this ladder. The higher the rung, the lower the threshold for biopsy.
White Lesions
Seven causes of "white." Distinguish by bilateral vs. unilateral, location, and whether it disappears on stretching.
White Sponge Nevus
Bilateral symmetrical thick folded white lesion at buccal mucosa — present from birth/childhood with family history.
Linea Alba
Bilateral asymptomatic white lines at buccal mucosa along the occlusal plane.
Leukoedema
Bilateral grey-white milky wrinkle/streak at buccal mucosa that disappears on stretch.
Frictional / Traumatic Keratosis
Solitary lesion ranging from pale-translucent to dense white at any traumatized mucosal site.
2. Incisional biopsy if no resolution after 2 wk.
Leukoplakia
White/grey plaque with well-demarcated but ill-defined borders that does not rub off.
Locations (low → high risk): vestibule · buccal mucosa · palate · alveolar ridge · lip · tongue · floor of mouth.
Etiology: tobacco (smoke or smokeless), alcohol abuse, tertiary syphilis.
2. Incisional biopsy if no resolution.
Hairy Leukoplakia
White plaque that does not rub off at lateral border of tongue (uni- or bilateral). Caused by EBV in immunocompromised patients (HIV, transplant, prolonged corticosteroid use).
HIV asymptomatic → systemic antiviral + medical eval.
AIDS → no treatment.
Verrucous Carcinoma
White (sometimes pink/erythematous) papillary surface projections with well-demarcated borders. Buccal mucosa · alveolar ridge · gingiva · palate.
Red Lesions
Two diagnoses, both with high malignancy concern. Treat as biopsy-mandatory until proven otherwise.
Erythroplakia
Red velvety lesion (multiple lesions possible) with HIGH malignant potential.
High-risk sites: floor of mouth · lateral tongue · retromolar tissues · soft palate.
2. Incisional biopsy without delay
3. Surgical excision per histology.
Squamous Cell Carcinoma
Early stage: white/red/mixed, painless or minimal pain.
Later stage: ulcerated + painful + induration + rolled borders.
Associated with HPV-16, tobacco, alcohol, sun (lip).
2. Incisional biopsy
3. Excision ± radiation/chemotherapy.
Immune-Mediated Lesions
Skin + oral involvement is the pattern. Nikolsky sign and Wickham striae are the dead-giveaways.
Lichen Planus
Skin: small purple polygonal flat-topped papules at flexor surfaces (wrists, ankles).
Oral — 6 forms: Reticular (most common, Wickham striae) · Plaque · Atrophic · Erosive · Bullous · Papular.
Symptomatic → topical corticosteroids.
Severe → systemic corticosteroids.
Erosive form: monitor for malignant transformation.
Lichenoid Mucositis
Lichen-planus-like reaction caused by NSAIDs, antihypertensives, antimalarials, amalgam, or other allergens. Resolves when offending agent removed.
Mucous Membrane Pemphigoid
Chronic autoimmune blistering of mucous membranes.
Eyes: conjunctival scarring, symblepharon, blindness if untreated.
Oral: desquamative gingivitis, painful erosions, positive Nikolsky sign.
Pemphigus Vulgaris
Severe autoimmune blistering of skin and mucous membranes. Oral often the first site — fragile bullae rupture quickly → painful erosions, positive Nikolsky.
Erythema Multiforme
Acute hypersensitivity reaction often triggered by HSV infection or medications.
Skin: classic "target lesions".
Oral: swollen, hemorrhagic, crusted lips + intraoral erosions.
Lupus Erythematosus
Skin: classic "butterfly malar rash" in SLE.
Oral: chronic erosions/ulcers + radiating white striae (similar to LP).
Wickham striae → lichen planus (lacy white pattern, especially reticular form).
Universal Diagnostic Approach
When the OSCE asks "What is the most appropriate management?" for an unknown lesion, the answer is almost always step 3 of this sequence.
Approach to any undiagnosed mucosal lesion