Pauci‐immune necrotizing glomerulonephritis in a 24‐year‐old female with negative ANCA antibodies: A rare case report.

Key Clinical Message: Pauci‐immune necrotizing glomerulonephritis (PING) is a small vessel renal vasculitis usually associated with the presence of antineutrophil cytoplasmic antibodies (ANCA) against myeloperoxidase or proteinase. A small proportion of PING patients do not have ANCA antibodies. A condition known as Pauci‐immune necrotizing glomerulonephritis, or PING for short, is a type of kidney inflammation that affects small blood vessels. This condition is typically linked with the existence of certain antibodies, specifically antineutrophil cytoplasmic antibodies or ANCA, which target myeloperoxidase or proteinase. However, it's worth noting that a minor percentage of individuals diagnosed with PING do not possess these ANCA antibodies. A 24‐year‐old woman with no previous medical history arrived at the ER due to various symptoms including joint pain, fever, difficulty swallowing, and shortness of breath. Despite multiple symptoms suggesting systemic lupus erythematosus (SLE), this diagnosis was ruled out based on the EULAR/ACR 2019 classification criteria and laboratory tests. Other potential diagnoses such as rheumatoid arthritis (RA) and eosinophilic garnulomatosis with polyaniitis (EGPA) were also excluded based on respective criteria. The patient was treated with a 3‐day course of methylprednisolone, followed by prednisolone, which improved her creatinine levels. Subsequent tests for P‐ANCA and C‐ANCA were negative. A kidney biopsy confirmed necrotizing glomerulonephritis, consistent with pauci‐immune vasculitis. A bronchoscopy revealed bleeding and hemorrhage in her lungs, but bacterial culture analysis was negative. The patient was given piperacillin, tazobactam, and vancomycin for septic coverage, as well as intravenous immunoglobulin (IVIg), which led to symptom improvement. [ABSTRACT FROM AUTHOR]