Rituximab therapy in severe PR3-ANCA pulmonary–renal syndrome: A clinical and pharmaceutical case report

Background : Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a rare systemic autoimmune disease characterized by necrotizing inflammation of small blood vessels. Pulmonary–renal syndrome represents one of the most severe clinical manifestations and is associated with high morbidity, rapid progression of renal failure, and increased mortality. Management requires individualized immunosuppressive therapy, careful pharmacological monitoring, and multidisciplinary care. Case presentation : The case of a 54-year-old male with proteinase 3 (PR3)-ANCA-positive vasculitis complicated by rapidly progressive glomerulonephritis, pulmonary infiltrates, and dialysis-dependent acute kidney injury is presented. The initial presentation mimicked severe infection and possible malignancy, which complicated the diagnostic process. Despite induction therapy with corticosteroids and cyclophosphamide, renal recovery was not achieved. Due to refractory disease activity and concerns regarding cumulative cyclophosphamide toxicity, rituximab therapy was initiated. Stabilization of systemic inflammatory activity and regression of pulmonary involvement were subsequently observed, although renal replacement therapy remained necessary. Conclusion : This case highlights the complexity of therapeutic decision-making in severe ANCA-associated pulmonary–renal syndrome. Rituximab represented an effective individualized therapeutic option in a dialysis-dependent patient with refractory disease. Careful pharmaceutical management, infection surveillance, and multidisciplinary monitoring remain essential during biologic immunosuppressive therapy.