Pemphigus

Pemphigus is a group of rare autoimmune blistering disorders characterized by loss of cell-to-cell adhesion (acantholysis) within the epidermis and mucous membranes, leading to flaccid bullae and erosions. The main forms are pemphigus vulgaris (PV), pemphigus foliaceus (PF), and paraneoplastic pemphigus (PNP). PV typically involves mucous membranes, especially the oral cavity, with skin lesions that are fragile; PF primarily affects the skin with crusted erosions and often spares mucosa; PNP is associated with an underlying neoplasm and can involve mucosa and skin with variable severity.

Pathophysiology involves autoantibodies directed against desmogleins, desmosomal cadherins that mediate keratinocyte adhesion. In PV, antibodies largely target desmoglein-3 (and sometimes desmoglein-1), whereas PF antibodies target desmoglein-1. This disrupts desmosomes, causing suprabasal acantholysis and intraepidermal blistering. Direct and indirect immunofluorescence typically reveal intercellular IgG deposits in the epidermis, and serology can detect anti-desmoglein antibodies.

Diagnosis relies on clinical presentation supported by skin or mucosal biopsies showing acantholysis, and immunofluorescence demonstrating intercellular IgG. ELISA or indirect immunofluorescence testing for anti-desmoglein antibodies can aid in diagnosis and monitoring.

Treatment aims to suppress autoantibody production and control inflammation. Regimens commonly include systemic corticosteroids with steroid-sparing immunosuppressants such as azathioprine or mycophenolate mofetil; rituximab has emerged as an effective targeted therapy. Adjunctive therapies include IVIG, plasmapheresis, and thorough wound care. Prognosis has improved with modern therapy, but relapses are common and treatment carries risks of infection and medication-related adverse effects. Regular follow-up and monitoring of disease activity and antibody titers guide management.