Case of Eosinophilic Granulomatosis with Polyangiitis with Kidney Involvement

Introduction: Eosinophilic granulomatosis with polyangiitis (EGPA) is a systemic small-vessel vasculitis characterized by asthma, eosinophilia, and ANCA positivity in 40% of patients. Though predominantly a rheumatological process, we present a case with severe renal disease. Case Description: A 42-year-old male with a history of asthma and tobacco abuse presents complaining of fever, abdominal pain, pleuritic pain, weakness, and weight loss. On admission he was febrile to 101.1F, lab studies were significant for WBC of 13.1, PLT 521, eosinophils 2.11, Cr 2.10 mg/dL from a baseline of 1.0, CRP 285. CT chest abdomen pelvis revealed moderate paraseptal emphysema. Blood and urine cultures, TB, RPR, HIV, and Hepatitis serologies were negative. Urine microscopy revealed acanthocytes and thus renal biopsy was sought. The patient had normal ANA and complement levels however ANCA serologies were positive with p-ANCA pattern at > 1:1250, PR3 Ab 75, and MPO Ab 193. His PLA2R Ab and GBM Ab were negative. The renal biopsy showed severe pauci-immune necrotizing crescentic glomerulonephritis and glomerular cellular crescents involving 66% of the glomeruli with prominent podocyte effacement. Rheumatology was consulted and diagnosed the patient with EGPA. The patient was given methylprednisolone at 1 g daily for 3 days followed by an initial dose of Rituximab 1 g when his Cr was 4.02 mg/dL. His Cr peaked at 4.57 mg/dL the following day before downtrending, and he was discharged on prolonged prednisone taper with follow-up with Rheumatology, Pulmonology, and Nephrology. The patient had IgG 1476, IgM 44, and IgA 197 baseline immunoglobulin levels. His 2nd dose of Rituximab was 3 weeks later and at a reduced dose of 800 mg IV due to issues with insurance authorization. The renal response stalled with a Cr level of 3 mg/dL 6 weeks after his 2nd dose of Rituximab and proteinuria worsened to 13 g/d. Adjunct therapy with Mepolizumab or Cytoxan was discussed with Rheumatology. His follow-up IgG 481, IgM 23, and IgA 108 precluded repeated dosing of Rituximab. Given the patient’s refractory EGPA with severe symptoms, the decision was made to proceed with Cytoxan therapy. Discussion: Renal involvement in EGPA occurs in about 25% of cases compared with other ANCA vasculitis and impacts the patient's prognosis and treatment. Treatment of EGPA with renal involvement is challenging and involves a multidisciplinary approach