Direct immunofluorescence of a facial scaly plaque in a middle-aged woman shows BOTH intercellular IgG throughout the epidermis AND granular IgM with C3 along the dermoepidermal junction in sun-exposed skin. Antinuclear antibody is positive. The diagnosis is:

• A Pemphigus erythematosus (Senear-Usher syndrome) ✓
• B Discoid lupus erythematosus
• C Bullous systemic lupus erythematosus
• D Pemphigus foliaceus

Explanation

Pemphigus erythematosus combines the immunopathology of pemphigus foliaceus (intercellular IgG against desmoglein 1) with that of lupus erythematosus (granular immunoglobulin and C3 at the dermoepidermal junction of sun-exposed skin), historically described as the grains and clumps pattern. Discoid lupus lacks intercellular staining, plain pemphigus foliaceus lacks the junctional band, and bullous SLE shows a sublamina densa linear IgG pattern instead.

Reference: Rook's Textbook of Dermatology, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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