10.3 Vesiculobullous & Immune-Mediated Mucosal Disease
Key Takeaways
- Pemphigus vulgaris is an intraepithelial blistering disease (desmoglein autoantibodies) with a positive Nikolsky sign and flaccid bullae that rupture into painful erosions; oral lesions often precede skin disease.
- Mucous membrane (cicatricial) pemphigoid is a subepithelial blistering disease targeting basement membrane antigens; oral desquamative gingivitis is common and ocular scarring risk makes multidisciplinary care essential.
- Direct immunofluorescence (DIF) patterns distinguish these diseases: intercellular IgG/C3 in pemphigus versus linear basement membrane zone IgG/C3 (or IgA) in pemphigoid.
- Erythema multiforme is an acute immune-mediated mucocutaneous reaction often triggered by HSV or drugs; oral crusting of lips and widespread ulcers appear with or without target skin lesions.
- Desquamative gingivitis is a clinical pattern—not a diagnosis—and requires workup for mucous membrane pemphigoid, pemphigus, and erosive lichen planus.
10.3 Vesiculobullous & Immune-Mediated Mucosal Disease
Quick Answer: Pemphigus vulgaris = intraepithelial split (anti-desmoglein), flaccid blisters, + Nikolsky, oral erosions often first, DIF = fishnet intercellular IgG/C3. Mucous membrane pemphigoid = subepithelial split, tense bullae, desquamative gingivitis, scarring risk (eyes!), DIF = linear basement membrane IgG/C3. Erythema multiforme = acute, often HSV- or drug-triggered, bloody lip crusts ± target skin lesions.
Chronic oral erosions that fail simple ulcer care belong in an autoimmune/vesiculobullous differential. AFK loves side-by-side comparison of pemphigus vs pemphigoid and recognition of EM versus primary viral infection.
Desquamative Gingivitis: A Pattern, Not a Diagnosis
| Feature | Detail |
|---|---|
| Clinical | Erythematous, glazed, friable gingiva; peeling epithelium; pain on brushing/eating |
| Common causes | Mucous membrane pemphigoid, erosive lichen planus, pemphigus vulgaris; less often hypersensitivity |
| Workup | History, full mouth/skin/eye review, perilesional biopsy for H&E and DIF (Michel’s medium or appropriate transport) |
| Error to avoid | Calling “desquamative gingivitis” the final diagnosis without identifying the disease |
Pemphigus Vulgaris (PV)
Pathophysiology
IgG autoantibodies against desmogleins (Dsg3 ± Dsg1)—cadherin proteins in desmosomes that glue keratinocytes together. Loss of adhesion → acantholysis → suprabasal intraepithelial cleft.
| Item | PV teaching fact |
|---|---|
| Split level | Intraepithelial (suprabasal) |
| Blister type | Flaccid, thin roof—ruptures easily → erosions dominate clinically in mouth |
| Nikolsky sign | Positive (gentle pressure/shear extends or induces blister on normal-appearing skin/mucosa in active disease) |
| Oral involvement | Very common; often precedes skin lesions by months |
| Oral look | Painful irregular erosions; soft palate, buccal mucosa, tongue; intact bullae rarely seen |
| Skin | Flaccid bullae, erosions, crusts when involved |
| Histology | Suprabasal split, acantholytic keratinocytes, tombstone basal cells |
| DIF | Intercellular IgG ± C3 throughout epithelium (“chicken wire/fishnet”) |
| IIF / ELISA | Circulating anti-Dsg antibodies; titers may track activity |
| Severity | Potentially life-threatening historically before immunosuppression/rituximab era |
Nikolsky sign: rubbing apparently normal skin/mucosa near a lesion causes sheet-like peeling or new blister. Strongly associated with pemphigus (also severe TEN/SSSS clinically—context differs). Mucous membrane pemphigoid more often shows a negative or less dramatic Nikolsky; some patients show a pseudo-Nikolsky on inflamed gingiva—do not rely on one sign alone.
Management principles (conceptual AFK level)
- Confirm with biopsy + DIF before long-term immunosuppression when possible (urgent treatment if severe)
- High-potency topical steroids for limited oral disease
- Systemic corticosteroids historically first-line for widespread disease
- Steroid-sparing immunosuppressants; rituximab is a modern cornerstone in many guidelines for moderate–severe PV
- Oral medicine/dermatology co-management; infection prophylaxis and bone health when on chronic steroids
- Dental care: gentle hygiene, soft diet during flares, avoid trauma
Mucous Membrane Pemphigoid (MMP) / Cicatricial Pemphigoid
Pathophysiology
Autoantibodies against basement membrane zone (BMZ) antigens (e.g., BP180/BPAG2, laminin-332/epiligrin, integrin subunits—exact antigen varies by subtype). Split is subepithelial → roof thicker → bullae may be tense before rupture.
| Item | MMP teaching fact |
|---|---|
| Split level | Subepithelial (below basal layer / at BMZ) |
| Blister type | Tense bullae when intact; heal with scarring potential on mucosa |
| Nikolsky | Typically negative (classic teaching vs PV) |
| Oral | Extremely common; desquamative gingivitis hallmark; erosions any mucosa |
| Eyes | Conjunctival involvement → scarring, symblepharon, blindness risk → ophthalmology essential if ocular disease |
| Other mucosa | Nasal, pharyngeal, laryngeal, esophageal, genital possible |
| Skin | Less dominant than in bullous pemphigoid of elderly, but can occur |
| Histology | Subepithelial blister; mixed inflammation; eosinophils variable |
| DIF | Linear IgG and/or C3 (sometimes IgA) along BMZ |
| Bullous pemphigoid (BP) | Related subepithelial disease—usually elderly with tense skin blisters and pruritus; oral less severe than classic MMP |
Scarring is why MMP is called cicatricial pemphigoid in older literature—critical functional risk in eyes and larynx.
Management principles
- Biopsy + DIF for diagnosis
- Topical corticosteroids (including custom trays for gingival disease) for oral-limited mild disease
- Dapsone sometimes used (G6PD screen) in selected mucosal disease
- Systemic immunosuppression for progressive/multi-site disease
- Mandatory eye evaluation when ocular symptoms/signs or high-risk disease
- Multidisciplinary (oral medicine, dermatology, ophthalmology, ENT)
Head-to-Head: PV vs MMP
| Feature | Pemphigus vulgaris | Mucous membrane pemphigoid |
|---|---|---|
| Autoantigen family | Desmogleins (desmosomes) | BMZ proteins (hemidesmosome/anchoring) |
| Anatomic split | Intraepithelial | Subepithelial |
| Blisters | Flaccid | Tense (when intact) |
| Nikolsky | Positive | Usually negative |
| Oral first? | Often yes | Oral very common (gingiva classic) |
| Scarring | Less the defining feature | Hallmark risk (esp. eyes) |
| DIF pattern | Intercellular IgG/C3 | Linear BMZ IgG/C3 (±IgA) |
| Key complication mindset | Widespread denudation, infection, electrolyte issues historically | Blindness, airway strictures, chronic oral pain |
Erythema Multiforme (EM)
EM is an acute, self-limited but recurrent, immune-mediated syndrome distinct from chronic autoimmune blistering diseases.
| Feature | Detail |
|---|---|
| Triggers | HSV (most common for EM minor); Mycoplasma pneumoniae (especially kids/young adults); drugs (less than SJS/TEN spectrum but possible) |
| Course | Sudden onset; resolves in ~2–4 weeks; may recur with HSV reactivations |
| Skin | Classic target (iris) lesions—concentric rings—on extremities; may be absent in EM-spectrum mucosal disease |
| Oral | Painful erosions, bloody crusted lips, widespread ulcers; intact vesicles short-lived |
| EM minor vs major | Major has more severe/extensive mucosal involvement (definitions vary in texts) |
| SJS/TEN | Drug-related severe epidermal necrolysis spectrum—different disease—widespread skin detachment, high mortality; urgent hospital care |
Dental differential: primary herpetic gingivostomatitis has fever and acute gingivitis in a first-infection host; EM often has lip crusting and target lesions with possible prior drug/HSV context. Stevens–Johnson involves severe systemic/skin disease—refer emergently.
Management: identify/stop culprit drug; treat HSV suppression if recurrent HSV-associated EM; supportive oral care (analgesia, hydration, soft diet, antiseptic rinses); systemic steroids controversial and specialist-guided; ophthalmology if ocular involvement; hospitalize if cannot drink or severe cutaneous disease.
Other Immune / Hypersensitivity Entities (Brief AFK Map)
| Condition | Oral clue | Notes |
|---|---|---|
| Erosive lichen planus | Wickham striae at margins; bilateral | DIF usually negative for PV/MMP patterns (fibrinogen shaggy BMZ sometimes) |
| Plasma cell gingivitis | Bright red gingiva related to allergens (flavorings) | Remove allergen |
| Contact stomatitis | Adjacent to denture/restoration materials | Patch testing sometimes |
| Lupus erythematosus | Oral discoid lesions, ulcers, lichenoid | Systemic workup if indicated |
| Behçet disease | Recurrent oral + genital ulcers ± uveitis | Medical diagnosis; pathergy |
| GVHD | Lichenoid oral changes post-transplant | Specialist context |
Diagnostic Workflow for Chronic Oral Blisters/Erosions
- History: onset acute vs chronic, drugs, HSV, eye/genital symptoms, skin lesions, weight loss, swallowing
- Exam: distribution, gingiva, eyes (referral), Nikolsky testing carefully, neck nodes (malignancy still in differential for chronic ulcers)
- Biopsy strategy:
- Lesional edge for routine H&E
- Perilesional normal-appearing mucosa for DIF
- Labs: IIF/ELISA for pemphigus/pemphigoid antibodies as available; CBC/G6PD before dapsone; infection screens as indicated
- Do not indefinitely prescribe empirical antifungals/antibiotics for classic autoimmune patterns without diagnosis
Practical Dental Chair Considerations
| Issue | Approach |
|---|---|
| Pain control | Topical anesthetics short-term; systemic analgesics; treat disease cause |
| Hygiene | Soft brushes, alcohol-free rinses; professional cleaning with gentle technique |
| Secondary infection | Candida common on steroids—monitor |
| Elective surgery | Defer during severe flares; medical clearance on immunosuppressants |
| Steroid inhalers / systemic steroids | Adrenal suppression, candidiasis, delayed healing awareness |
Rapid review list
- PV: anti-Dsg, intraepithelial, flaccid, +Nikolsky, fishnet DIF, mouth often first
- MMP: anti-BMZ, subepithelial, tense, desquamative gingivitis, linear DIF, watch the eyes
- Desquamative gingivitis = pattern → find the disease
- EM: acute, HSV/drugs, crusted lips ± targets; not the same as SJS/TEN
- Always pair H&E with DIF for suspected autoimmune blistering disease
- Erosive LP remains a major differential for chronic oral erosions
Together with 10.1 and 10.2, you can classify most AFK mucosal vignettes: infection vs reactive vs premalignant/malignant vs autoimmune.
Which immunofluorescence pattern is expected in pemphigus vulgaris?
A patient has painful oral erosions, flaccid bullae on skin, and a positive Nikolsky sign. Histology shows a suprabasal cleft with acantholysis. The most likely diagnosis is:
Why is ophthalmology involvement particularly important in mucous membrane pemphigoid?
A young adult develops acute painful oral ulcers with severe hemorrhagic crusting of the lips one week after a herpes labialis outbreak and has target lesions on the hands. The best diagnosis is: