Pemphigus vulgaris vs Bullous pemphigoid and dermatitis herpetiformis
How to tell Pemphigus vulgaris and Bullous pemphigoid and dermatitis herpetiformis apart when a board question makes them look alike.
Pemphigus is flaccid mucosal intraepidermal anti-desmoglein; pemphigoid is tense subepidermal hemidesmosome; dermatitis herpetiformis is itchy grouped IgA/celiac.
Side by side
Pemphigus vulgaris causes flaccid bullae, erosions, mucosal involvement, positive Nikolsky sign, and IgG against desmoglein with suprabasal acantholysis.
Bullous pemphigoid causes tense bullae in older adults from hemidesmosome antibodies; dermatitis herpetiformis causes grouped itchy vesicles on extensor surfaces with IgA in dermal papillae and celiac disease.
Anti-desmoglein antibodies disrupt keratinocyte adhesion within epidermis.
Bullous pemphigoid disrupts dermal-epidermal anchoring; dermatitis herpetiformis deposits IgA in dermal papillae.
Fishnet intercellular IgG, mucosal erosions, and suprabasal split support pemphigus vulgaris.
Linear IgG/C3 at basement membrane supports bullous pemphigoid; granular IgA at dermal papillae supports dermatitis herpetiformis.
The trap
Blisters overlap, so tense versus flaccid, mucosa, Nikolsky, and immunofluorescence pattern separate them.
The repair move
For blistering disease, use blister tension, mucosal involvement, split level, and immunofluorescence.
Try a free question
CoreA 52-year-old woman has 3 months of painful oral erosions and flaccid skin bullae that rupture easily, leaving raw, painful erosions. Nikolsky sign is positive. Skin biopsy shows intraepidermal acantholysis. Direct immunofluorescence shows IgG deposits in an intercellular 'net' pattern around keratinocytes. Anti-desmoglein 1 and 3 antibodies are positive. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Pemphigus vulgaris. Pemphigus vulgaris features painful flaccid intraepidermal bullae with prominent mucosal involvement (oral erosions), positive Nikolsky sign, anti-desmoglein 1 and 3 antibodies, and intercellular 'net' IgG on DIF; treatment is high-dose corticosteroids plus steroid-sparing agents.
Why the other choices are tempting
- B. Bullous pemphigoid features TENSE subepidermal bullae in elderly patients, negative Nikolsky sign, anti-BP180/BP230 antibodies, and linear IgG/C3 at the basement membrane.
- C. Dermatitis herpetiformis has small pruritic vesicles on extensor surfaces with granular IgA deposits.
- D. SJS/TEN is acute drug-induced epidermal necrolysis with diffuse mucosal involvement and elevated mortality.
- E. TEN affects >30% body surface area.
Flashcards
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What antibody target supports pemphigus vulgaris?
Anti-desmoglein antibodies support pemphigus vulgaris.
What immunofluorescence supports dermatitis herpetiformis?
Granular IgA in dermal papillae supports dermatitis herpetiformis.
Quick answers
What is the fastest way to tell Pemphigus vulgaris from Bullous pemphigoid and dermatitis herpetiformis?
Pemphigus is flaccid mucosal intraepidermal anti-desmoglein; pemphigoid is tense subepidermal hemidesmosome; dermatitis herpetiformis is itchy grouped IgA/celiac.
What is the key clue for Pemphigus vulgaris?
Pemphigus vulgaris causes flaccid bullae, erosions, mucosal involvement, positive Nikolsky sign, and IgG against desmoglein with suprabasal acantholysis.
What is the key clue for Bullous pemphigoid and dermatitis herpetiformis?
Bullous pemphigoid causes tense bullae in older adults from hemidesmosome antibodies; dermatitis herpetiformis causes grouped itchy vesicles on extensor surfaces with IgA in dermal papillae and celiac disease.
What is the common trap with Pemphigus vulgaris vs Bullous pemphigoid and dermatitis herpetiformis?
Blisters overlap, so tense versus flaccid, mucosa, Nikolsky, and immunofluorescence pattern separate them.