Bullous pemphigoid vs Pemphigus vulgaris
How to tell Bullous pemphigoid and Pemphigus vulgaris apart when a board question makes them look alike.
Step 2 CK pairs are in open beta while clinical review finishes. Spot an issue? Tell us.
Presence of mucosal erosions with flaccid bullae is the fastest discriminator for pemphigus vulgaris.
Side by side
Tense pruritic bullae in older adults with minimal mucosal involvement suggest bullous pemphigoid.
Flaccid bullae with painful oral erosions and positive Nikolsky sign suggest pemphigus vulgaris.
IgG against hemidesmosomal proteins at the dermal-epidermal junction causes subepidermal blistering.
IgG against desmogleins disrupts keratinocyte adhesion and causes intraepidermal acantholysis.
Skin biopsy with direct immunofluorescence shows linear IgG and C3 along the basement membrane; BP180 or BP230 antibodies may be elevated.
Biopsy shows suprabasal acantholysis and direct immunofluorescence with intercellular net-like IgG; anti-desmoglein 1 and 3 antibodies are supportive.
The trap
A major trap is treating all blistering disease as benign dermatitis. The resolving clue is skin fragility plus oral mucosal involvement, which should prompt urgent biopsy and systemic immunosuppression for pemphigus vulgaris.
The repair move
Next best step: perform punch biopsy of lesional and perilesional skin for histology and direct immunofluorescence. Start high-potency topical corticosteroid for limited bullous pemphigoid or systemic prednisone around 0.5 mg/kg/day for extensive disease; for pemphigus vulgaris, initiate systemic corticosteroids plus steroid-sparing therapy such as rituximab in severe cases.
Try a free question
CoreA 68-year-old patient has painful oral erosions and easily ruptured skin bullae with positive Nikolsky sign. What is the next best step in management?
Show answer and explanation
Answer: A. Biopsy with direct immunofluorescence and start systemic corticosteroids. Clinical suspicion for pemphigus vulgaris requires immediate diagnostic confirmation and systemic immunosuppressive treatment.
Why the other choices are tempting
- B. Topical antifungals do not treat autoimmune blistering disease.
- C. Observation delays needed therapy and increases complications.
- D. Iron supplementation is unrelated.
- E. Patch testing is not the key diagnostic test for pemphigus vulgaris.
Flashcards
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Which blister quality is typical of bullous pemphigoid?
Tense bullae that are less likely to rupture quickly.
What mucocutaneous pattern points to pemphigus vulgaris?
Painful oral erosions with flaccid skin bullae and epidermal fragility.
Quick answers
What is the fastest way to tell Bullous pemphigoid from Pemphigus vulgaris?
Presence of mucosal erosions with flaccid bullae is the fastest discriminator for pemphigus vulgaris.
What is the key clue for Bullous pemphigoid?
Tense pruritic bullae in older adults with minimal mucosal involvement suggest bullous pemphigoid.
What is the key clue for Pemphigus vulgaris?
Flaccid bullae with painful oral erosions and positive Nikolsky sign suggest pemphigus vulgaris.
What is the common trap with Bullous pemphigoid vs Pemphigus vulgaris?
A major trap is treating all blistering disease as benign dermatitis. The resolving clue is skin fragility plus oral mucosal involvement, which should prompt urgent biopsy and systemic immunosuppression for pemphigus vulgaris.