A 40-year-old woman presents with widespread tense bullae on erythematous and urticarial plaques, predominantly on the trunk and flexural areas. Mucosal surfaces are spared. Direct immunofluorescence shows linear IgG and C3 deposition along the basement membrane zone. Salt-split skin shows staining on the epidermal side. What is the most likely diagnosis?

• A Pemphigus vulgaris
• B Epidermolysis bullosa acquisita
• C Dermatitis herpetiformis
• D Bullous pemphigoid ✓

Explanation

Bullous pemphigoid presents with tense bullae on erythematous/urticarial plaques, flexural predominance, and mucosal sparing. Direct immunofluorescence shows linear IgG and C3 at the BMZ. Salt-split skin showing epidermal (roof) staining localizes the antigen to hemidesmosomal proteins (BP180, BP230), confirming bullous pemphigoid. EBA shows dermal (floor) staining as type VII collagen is in the sublamina densa. Pemphigus shows intercellular staining. This pattern distinguishes the two major autoimmune blistering diseases.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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