5.1 Ulcerative, Vesiculobullous & Immune-Mediated Oral Mucosal Diseases

5.1 Ulcerative, Vesiculobullous & Immune-Mediated Oral Mucosal Diseases

Oral mucosal diseases encompass a broad spectrum of ulcerative, vesiculobullous, and immune-mediated disorders. Accurate clinical diagnosis requires a thorough understanding of etiology, clinical presentation, histopathology, direct immunofluorescence (DIF), and evidence-based therapeutic interventions recommended in Therapeutic Guidelines: Dentistry (eTG Dentistry).

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1. Recurrent Aphthous Stomatitis (RAS)

Recurrent Aphthous Stomatitis (RAS) is the most common non-traumatic ulcerative disorder of the oral mucosa, affecting 10–20% of the population. RAS characteristically presents as painful, recurrent, well-demarcated ulcers confined almost exclusively to non-keratinized oral mucosa (e.g., buccal and labial mucosa, ventral tongue, floor of mouth, soft palate).

Clinical Subtypes of RAS

Etiology & Systemic Workup

While idiopathic T-cell-mediated mucosal immune responses drive RAS, candidates in the Australian Dental Council examination must recognize underlying predisposing factors requiring haematological and systemic investigation:

• Haematinic Deficiencies: Deficiencies in ferritin (iron), folate, or vitamin B12 occur in up to 20% of RAS patients.
• Gastrointestinal & Systemic Diseases: Coeliac disease, Inflammatory Bowel Disease (Crohn's disease, Ulcerative Colitis), Behçet syndrome (triad of oral aphthae, genital ulcers, and uveitis), and HIV infection.
• Triggers: Local trauma, stress, sodium lauryl sulfate (SLS) in dentifrices, and systemic drug reactions.

Pharmacological Management (eTG Dentistry)

• First-Line Topical Therapy: Topical corticosteroid application to reduce pain and inflammation during the prodromal phase.
  • Triamcinolone acetonide 0.1% in dental paste (Orabase) applied after meals and at bedtime 2–4 times daily.
  • Hydrocortisone sodium succinate 2.5 mg buccal tablets allowed to dissolve near the lesion 4 times daily.
• Severe / Widespread Recurrences: Betamethasone dipropionate 0.5 mg dissolved in 10 mL water as a 2-minute oral rinse (spit out) 2–4 times daily.
• Systemic Therapy: Reserved for refractory major aphthae under specialist Oral Medicine supervision (e.g., short-course systemic prednisolone, colchicine, or thalidomide).

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2. Autoimmune Vesiculobullous Diseases

Autoimmune vesiculobullous diseases are caused by autoantibodies directed against cellular adhesion molecules within the epithelium or basement membrane zone.

       Pemphigus Vulgaris                   Mucous Membrane Pemphigoid
┌─────────────────────────────────┐    ┌─────────────────────────────────┐
│ Autoantibody vs Desmoglein 3    │    │ Autoantibody vs BP180 / BP230   │
│ Intraepithelial Acantholysis    │    │ Subepithelial Clefting (BMZ)    │
│ Nikolsky Sign: POSITIVE         │    │ Nikolsky Sign: VARIABLE / MIN   │
│ DIF: Net-like Intraepithelial   │    │ DIF: Linear Basement Membrane   │
└─────────────────────────────────┘    └─────────────────────────────────┘

A. Pemphigus Vulgaris (PV)

Pemphigus Vulgaris is a life-threatening, intraepithelial autoimmune blistering disorder. In 50–70% of cases, oral lesions precede cutaneous lesions by several months, highlighting the dentist's crucial role in early diagnosis.

• Immunopathogenesis: Autoantibodies (IgG) target Desmoglein 3 (and Desmoglein 1), a transmembrane desmosomal cadherin protein, disrupting cell-to-cell adhesion between keratinocytes (acantholysis).
• Clinical Presentation: Flaccid bullae that rupture rapidly, leaving extensive, painful, irregular erosion surfaces on both keratinized and non-keratinized mucosa. Desquamative gingivitis is common.
• Nikolsky Sign: Positive (applying firm lateral pressure to clinically normal-appearing mucosa induces bulla formation or epithelial sloughing).
• Histopathology: Intraepithelial / suprabasal clefting. Basal cells remain attached to the basement membrane via hemidesmosomes, creating a characteristic "row of tombstones" appearance. Tzanck cells (acantholytic rounded keratinocytes) are present within the fluid.
• Direct Immunofluorescence (DIF): Demonstrates fishnet-like or net-like intraepithelial intercellular deposition of IgG and C3 throughout the spinous layer.
• Management: High-dose systemic corticosteroids (prednisolone) combined with steroid-sparing immunosuppressive agents (azathioprine, mycophenolate mofetil, or rituximab) managed collaboratively with an Oral Medicine specialist and dermatologist.

B. Mucous Membrane Pemphigoid (MMP / Cicatricial Pemphigoid)

Mucous Membrane Pemphigoid is a chronic autoimmune subepithelial blistering disease predominantly affecting mucosal sites (oral cavity, conjunctiva, nasopharynx, larynx, esophagus).

• Immunopathogenesis: Autoantibodies (IgG, IgA, C3) target structural components of hemidesmosomes and the basement membrane zone (BMZ), including BP180 (collagen XVII), BP230, and laminin-332.
• Clinical Presentation: Tense, thick-walled bullae that may remain intact for days before rupturing into painful ulcers. Desquamative gingivitis (bright red, glazed, peeling gingiva) is the most frequent oral manifestation.
• Ocular Complications: Conjunctival involvement leads to scarring, symblepharon (adhesion of eyelid to eyeball), trichiasis, and irreversible blindness. Any patient diagnosed with MMP MUST be referred urgently to an ophthalmologist.
• Histopathology: Subepithelial clefting with total separation of the intact full-thickness epithelium from the underlying lamina propria, accompanied by a dense chronic inflammatory infiltrate.
• Direct Immunofluorescence (DIF): Demonstrates a smooth, continuous linear band of IgG and/or C3 deposition along the basement membrane zone.
• Management: Topical high-potency corticosteroids (e.g., clobetasol propionate or betamethasone dipropionate) for localized oral disease; systemic immunosuppressants (dapsone, prednisolone, mycophenolate) for widespread or ocular involvement.

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3. Oral Lichen Planus (OLP) & Lichenoid Lesions

Oral Lichen Planus (OLP) is a chronic T-cell-mediated inflammatory disease of unknown primary etiology targeting basal keratinocytes.

Clinical Variants of OLP

1. Reticular OLP: The most common form, characterized by asymptomatic or mildly tender slender, raised, white interlocking lines (Wickham striae) surrounded by an erythematous border, typically presenting bilaterally on the posterior buccal mucosa.
2. Erosive / Atrophic OLP: Painful, erythematous areas of mucosal erosion and ulceration bordered by radiating reticular white striae. Frequently manifests as desquamative gingivitis.
3. Plaque-like, Papular, & Bullous OLP: Less common forms presenting as fixed white plaques (resembling leukoplakia) or fluid-filled bullae that rupture into erosions.

Oral Lichenoid Lesions (OLL) vs OLP

• Oral Lichenoid Contact Lesions: Unilateral lesions occurring in direct anatomical contact with dental restorations (most commonly dental amalgam due to mercury hypersensitivity).
• Oral Lichenoid Drug Eruptions: Lesions associated with systemic drug ingestion, including NSAIDs, ACE inhibitors (captopril, enalapril), beta-blockers, thiazide diuretics, and antimalarials.

Histopathology of OLP

• Hyperkeratosis (or parakeratosis) with thickening of the granular layer.
• Saw-tooth wave-like appearance of rete ridges.
• Liquefactive degeneration of the basal cell layer.
• Civatte bodies (apoptotic keratinocytes) in the basal and parabasal zones.
• Dense, band-like infiltrate of T-lymphocytes restricted to the immediate subepithelial connective tissue zone.

Treatment Protocol (eTG Dentistry)

• Asymptomatic reticular OLP requires reassurance and clinical monitoring (at least annual monitoring due to ~1% risk of malignant transformation over 10 years).
• Symptomatic erosive/atrophic OLP treatment:
  • Topical Triamcinolone acetonide 0.1% in Orabase applied 3–4 times daily after meals.
  • Betamethasone dipropionate 0.5 mg rinse (dissolved in 10 mL water) held in the mouth for 2 minutes 2–4 times daily.
  • Replacement of amalgam restorations if direct anatomical contact with lichenoid lesion is confirmed.

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4. Erythema Multiforme (EM)

Erythema Multiforme is an acute, self-limiting, immune-complex-mediated hypersensitivity reaction.

• Etiology:
  • EM Minor: Triggered in >70% of cases by Herpes Simplex Virus (HSV) reactivation.
  • EM Major / Stevens-Johnson Syndrome (SJS): Severe form triggered primarily by adverse drug reactions (e.g., sulfonamides, anticonvulsants, NSAIDs, penicillins).
• Clinical Presentation: Rapid onset of painful mucosal ulcerations, characteristic hemorrhagic crusting of the lips, and classic cutaneous "target" or "bullseye" concentric ring lesions on hands and extensor surfaces.
• Management: Withdrawal of causative drug, systemic antiviral therapy (aciclovir) if HSV-induced, supportive fluid hydration, topical/systemic corticosteroids, and urgent hospital admission for SJS/TEN.