Rituximab in Autoimmune Blistering Diseases

Overview / Definition Rituximab is a chimeric monoclonal antibody that specifically targets the CD20 antigen on B cells. It is primarily used in the treatment of certain malignancies and autoimmune disorders, including autoimmune blistering diseases such as pemphigus vulgaris and bullous pemphigoid. By depleting B cells, rituximab reduces the production of pathogenic autoantibodies, thus facilitating disease remission. Epidemiology Autoimmune blistering diseases are rare conditions, with the incidence of pemphigus vulgaris estimated at 0.1 to 0.5 cases per 100,000 person-years. Bullous pemphigoid is more common, with an incidence of 10 to 50 cases per 100,000 person-years, often affecting older adults. Rituximab is increasingly used in these conditions, especially when first-line therapies are inadequate or poorly tolerated. Pathophysiology / Mechanism The pathophysiology of autoimmune blistering diseases involves the production of autoantibodies against specific proteins in the skin. In pemphigus vulgaris, antibodies target desmogleins, leading to loss of cell adhesion and blister formation. Bullous pemphigoid involves antibodies against hemidesmosomal proteins, resulting in subepidermal blistering. Rituximab acts by: Depleting B cells through complement-dependent cytotoxicity. Reducing autoantibody production, which is critical for disease progression. Inducing long-term B cell depletion, with potential lasting effects on disease control. Clinical Presentation The clinical manifestations of autoimmune blistering diseases vary based on the specific condition: Pemphigus vulgaris: Flaccid blisters that rupture easily, leading to painful erosions, often starting in the oral mucosa. Bullous pemphigoid: Tense blisters that are often pruritic and can occur on the trunk and extremities, typically sparing mucosal surfaces. Diagnosis / Workup Diagnosis of autoimmune blistering diseases typically involves: Clinical examination and history-taking to assess blister characteris