441. A Case of Microscopic Polyangiitis after Pfizer-BioNTech SARS-CoV-2 Vaccination in an Elderly Asian Male Patient

Presentation of Case: An 80-year-old Japanese man with renal insufficiency after Pfizer-BioNTech SARS-CoV-2 vaccine administration was admitted to our hospital. He had no history of decreased kidney function or abnormal urine tests. Three weeks after receiving the second dose of vaccination, he developed malaise. Subsequently, he was diagnosed with high inflammatory response and abnormal renal function and was referred to our hospital. At the time of admission, his blood pressure was 142/95 mmHg, body temperature was 38.9˚C, and SpO₂ was 97%. On physical examination, there was no skin rash or joint pain to suggest collagen or autoimmune diseases.

Diagnostic Testing: His blood tests showed an elevated serum creatinine (Cre) level of 4.52 mg/dL; serum proteinase-3 antineutrophil cytoplasmic antibodies (ANCA) level of <0.5 IU/mL; serum myeloperoxidase-O ANCA level of  >134 IU/mL; serum anti-glomerular basement membrane antibody level of <2.0 IU/mL; and C3/C4 of 90/27 mg/dL. Urinalysis showed proteinuria of 1.45 g/gCre and numerous urinary red blood cells. Kidney biopsy revealed severe pauci-immune crescentic necrotizing glomerulonephritis with vasculitis of the renal vessel wall (Fig. 1).

Results: Based on the results of serological and histological examinations, a diagnosis of microscopic polyangiitis was established. He was treated with high-dose oral steroids from day 2 after admission. Rituximab was administered on day 5, and plasma exchange therapy was provided on days 9–11. His condition gradually improved, and he was discharged on day 39. On his 2-month follow-up, his serum Cre level had improved to 2.03 mg/dL.

Discussion: There are some case reports of microscopic polyangiitis after SARS-CoV-2 vaccination from Europe and the United States; however, the association between microscopic polyangiitis and SARS-CoV-2 vaccination is unclear. To our knowledge, this is the first case report from Asia. The number of cases may increase with the increasing vaccination rate against SARS-CoV-2 and the start of the third phase of vaccination. Vasculitis should be differentiated in cases of prolonged fever after vaccination.

Disclosures: None