Microscopic Polyangiitis Following mRNA COVID-19 Vaccination: A Case Report.

Coronavirus disease 2019 (COVID-19) is one of the most widespread viral infections in human history. As a breakthrough against infection, vaccines have been developed to achieve herd immunity. Here, we report the first case of microscopic polyangiitis (MPA) following BNT162b2 vaccination in Korea. A 42-year-old man presented to the emergency room with general weakness, dyspnea, and edema after the second BNT162b2 vaccination. He had no medical history other than being treated for tuberculosis last year. Although his renal function was normal at last year, acute kidney injury was confirmed at the time of admission to the emergency room. His serum creatinine was 3.05 mg/dL. Routine urinalysis revealed proteinuria (3+) and hematuria. When additional tests were performed for suspected glomerulonephritis, the elevation of myeloperoxidase (MPO) antibody (38.6 IU/mL) was confirmed. Renal biopsy confirmed pauci-immune anti-neutrophil cytoplasmic antibody (ANCA)-related glomerulonephritis and MPA was diagnosed finally. As an induction therapy, a combination of glucocorticoid and rituximab was administered, and plasmapheresis was performed twice. He was discharged after the induction therapy and admitted to the outpatient clinic 34 days after induction therapy. During outpatient examination, his renal function had improved with serum creatinine 1.51 mg/dL. We suggest that MPA needs to be considered if patients have acute kidney injury, proteinuria, and hematuria after vaccination.