A 55-year-old man presents with crusted erosions in a seborrhoeic distribution over the scalp, face and upper trunk. There are no oral lesions. Biopsy shows a blister in the subcorneal/granular layer with acantholytic keratinocytes. DIF reveals intercellular IgG restricted to the upper layers of the epidermis. The most likely diagnosis is:

• A Pemphigus foliaceus ✓
• B Pemphigus vulgaris
• C Bullous pemphigoid
• D Darier disease

Explanation

Pemphigus foliaceus features autoantibodies to desmoglein 1, which is expressed mainly in the upper epidermis. The split therefore occurs subcorneally in the granular layer, and the DIF intercellular pattern is limited to the superficial epidermis. In pemphigus vulgaris the antibody targets desmoglein 3 (with desmoglein 1 in mucocutaneous disease), giving suprabasal splitting and fishnet staining throughout the whole epidermis, plus oral lesions.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.