Literature review and case study of recurrent EPGA with elevated IgG4 and positive HBsAg successfully treated with rituximab.

Background: Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare form of autoimmune vasculitis. The involvement of IgG4 and HBsAg in EGPA is less common but can occur and may present unique challenges in management.

Case Presentation: We present a case study of a 70-year-old female diagnosed with EGPA confirmed renal biopsy. She initially presented with recurrent purpura, diarrhea and progressive numbness in the hands and feet, accompanied by general weakness. Complete remission was achieved with a one-year course of prednisone acetate and cyclophosphamide treatment. However, upon discontinuation of self-medication, the disease relapsed, manifesting as a generalized rash and weakness in the extremities.Skin biopsy revealed eosinophil infiltration, with inflammatory cells predominantly surrounding blood vessels. Notably, during treatment, the patient's hepatitis B markers transitioned from negative to positive for HBsAg. Subsequent administration of entecavir, along with monitoring for a decrease in HBV DNA levels, preceded the initiation of steroids and rituximab to attain remission once more. Among the remaining 15 patients analyzed, all exhibited elevated serum IgG4 levels, with none testing positive for hepatitis B. Notably, only one patient was diagnosed with immunoglobulin G4-related disease (IgG4-RD), suggesting that elevated IgG4 levels alone may not necessarily indicate IgG4-RD.

Conclusions: Our case report highlights the first instance of recurrent EGPA accompanied by elevated IgG4 and positivity for hepatitis B, which was successfully treated with rituximab. In cases of concurrent hepatitis B, rituximab treatment may be considered once viral replication is under control. However, emphasis on maintenance therapy is crucial following the induction of disease remission.