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?
Intercellular (fishnet) epithelial IgG and C3 deposition
Linear IgA/IgG deposition only along the basement membrane zone
No immunoreactants; diagnosis is made only by fungal stain
Granular IgA in dermal papillae as in dermatitis herpetiformis skin only, never oral workup relevance
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:
Mucous membrane pemphigoid
Pemphigus vulgaris
Geographic tongue
Minor recurrent aphthous stomatitis
Why is ophthalmology involvement particularly important in mucous membrane pemphigoid?
Because MMP never affects the mouth, only the cornea
Because Nikolsky sign is tested only on the eyelid
Because conjunctival scarring can progress to symblepharon and vision loss even when oral disease is the presenting complaint
Because erythroplakia is defined as an eye disease
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:
Proliferative verrucous leukoplakia
Actinic cheilitis from chronic sun exposure
Median rhomboid glossitis
Erythema multiforme, often HSV-triggered
Sections you finish are checked off in the contents.