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Pemphigus Vulgaris — SCE Dermatology MCQ

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HardBlistering DiseasesPemphigus VulgarisSCE Dermatology

A 55-year-old man with pemphigus vulgaris has mucosal-dominant disease with severe oral erosions. His anti-Dsg3 is strongly positive and anti-Dsg1 is negative. According to the desmoglein compensation theory, why does he have mucosal but not cutaneous disease?

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Correct answer: B — In mucosae, Dsg3 is the predominant desmoglein without Dsg1 compensation — anti-Dsg3 alone causes mucosal blistering; in skin, Dsg1 compensates for Dsg3 loss, maintaining epidermal integrity

The desmoglein compensation theory explains pemphigus phenotypes: Mucosae express predominantly Dsg3 with limited Dsg1. When anti-Dsg3 alone is present, mucosal adhesion is disrupted but cutaneous Dsg1 compensates for Dsg3 loss in the skin, maintaining epidermal integrity → mucosal-dominant PV. When both anti-Dsg3 AND anti-Dsg1 are present, both mucosal and cutaneous adhesion are disrupted → mucocutaneous PV. In pemphigus foliaceus (anti-Dsg1 only), superficial epidermal blistering occurs (Dsg1 predominates in superficial epidermis) with mucosal sparing (Dsg3 compensates in mucosae). This elegant model explains the clinical phenotype-serotype correlation in pemphigus.

Reference: BAD 2017 Pemphigus; Amagai Desmoglein Compensation