Eosinophilic Granulomatosis with Polyangiitis Presenting as Acute Abdomen: A Rare Case Report.

Background: ANCA-associated vasculitis (AAV) is a group of autoimmune diseases characterized by necrotizing inflammation and fibrinoid necrosis of small- and medium-sized blood vessels. Renal involvement is common in AAV; however, renal hemorrhage is extremely rare, particularly in cases of eosinophilic granulomatosis with polyangiitis (EGPA). Spontaneous renal hemorrhage often presents as acute abdomen. Case Presentation: We report a 51-year-old male with a prior diagnosis of EGPA who presented to the emergency department with acute left-sided abdominal pain and signs of hypovolemic shock. Imaging revealed a massive left perirenal hematoma without active contrast extravasation, suggestive of renal rupture. Initial management focused on hemostasis and stabilization, but recurrent contralateral renal hemorrhage occurred during hospitalization. Further immunological, histopathological, and bone marrow evaluations confirmed EGPA complicated by renal involvement. The patient was treated with corticosteroids, cyclophosphamide, and rituximab, but recurrent hemorrhage indicated rapid disease progression or insufficient therapeutic response. Due to financial constraints, the patient was discharged prematurely, precluding long-term follow-up. Discussion: This case highlights the complexity of diagnosing and managing AAV-associated renal hemorrhage, particularly in EGPA patients. While the renal vascular changes observed, such as inflammation and potential necrosis, may be linked to the underlying vasculitis in EGPA, causality should be interpreted with caution, as other factors like coagulopathy, concurrent infections, or iatrogenic effects could contribute. Current literature suggests that ANCA-associated mechanisms, including NETs formation, play a role in vascular damage, but direct causation in rare complications like renal hemorrhage remains uncertain and requires further investigation. While EGPA treatment primarily involves immunosuppressive therapy targeting vasculitis and eosinophilia, spontaneous renal hemorrhage requires an integrated approach, including conservative management, interventional embolization, or surgical exploration in life-threatening cases. Reports of AAV-associated renal hemorrhage are rare, and large-scale studies are lacking, necessitating further research to optimize treatment strategies.