Pemphigus Vulgaris: Autoantibody-Mediated Blistering

Overview / Definition Pemphigus vulgaris (PV) is a rare, potentially life-threatening autoimmune blistering disorder primarily affecting the skin and mucous membranes. It is characterized by the presence of circulating autoantibodies that target desmogleins, which are adhesion proteins in the desmosomes of keratinocytes. The disruption of these proteins leads to acantholysis and the formation of intraepithelial blisters. Epidemiology Incidence: PV has an incidence ranging from 0.1 to 0.5 per 100,000 individuals per year. Prevalence: The prevalence is estimated to be between 1-5 cases per 100,000 individuals. Demographics: Most commonly affects middle-aged adults, with a peak incidence between the ages of 40 and 60 years. There is a slight female predominance. Geographic Variability: Higher incidence rates are seen in Jewish populations and individuals of Mediterranean descent. Pathophysiology / Mechanism The pathophysiology of pemphigus vulgaris involves the generation of autoantibodies against desmoglein 1 and desmoglein 3, which are cadherin-type adhesion molecules found in desmosomes. The binding of these autoantibodies leads to: Disruption of keratinocyte adhesion. Acantholysis, which is the loss of connections between keratinocytes. Formation of intraepithelial blisters that can progress to erosions. This autoimmune process is often triggered by environmental factors, including medications, infections, and UV exposure in genetically predisposed individuals. Clinical Presentation The classic presentation of pemphigus vulgaris includes: Skin involvement: Flaccid blisters that easily rupture, leading to painful erosions. Commonly affected areas include the scalp, face, trunk, and axillary regions. Mucosal involvement: Oral mucosa is often the first site affected, presenting as painful ulcers and erosions, leading to difficulty in eating and swallowing. Negative Nikolsky sign: The skin does not separate easily when lateral pressure is applied, unlike in pemphigus f