Abstract: PUB146
ANCA-Associated Segmental Necrotizing and Crescentic Glomerulonephritis with Predominant Acute Interstitial Nephritis Without Albuminuria
Session Information
Category: Glomerular Diseases
- 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics
Authors
- Liu, Wen, Robert Wood Johnson University Hospital, New Brunswick, New Jersey, United States
- Appelbaum, Zachary, Robert Wood Johnson University Hospital, New Brunswick, New Jersey, United States
- Thoonkuzhy, Sonia, Robert Wood Johnson University Hospital, New Brunswick, New Jersey, United States
Group or Team Name
- RWJMS Nephrology
Introduction
ANCA associated vasculitis (AAV) typically presents with non nephrotic proteinuria, microscopic hematuria, and acute kidney injury (AKI), often due to rapidly progressive glomerulonephritis (GN). We report an atypical case of AAV in a patient without albuminuria with a biopsy notable for concurrent acute interstitial nephritis (AIN).
Case Description
A 69 year old woman presented to the Emergency Room with 2 weeks of generalized weakness, poor oral intake, and dysuria. Her medical history consisted of recurrent pyelonephritis, nephrolithiasis, overactive bladder, hypertension, hyperlipidemia, meningioma, and hypothyroidism. Laboratory studies demonstrated severe AKI, with a serum creatinine of 4.1 mg/dL (baseline 0.8 mg/dL). Urinalysis demonstrated 2+ blood, 1+ protein, 36 RBCs/hpf, 84 WBCs/hpf, a urine protein to creatinine ratio of 1056 mg/g, but an undetectable urine albumin to creatinine ratio. No RBC casts or dysmorphic RBCs were identified. Serologic testing revealed a positive MPO antibody with pANCA titer of 1:640. Kidney biopsy demonstrated pauci-immune segmental necrotizing and crescentic glomerulonephritis with prominent AIN. Despite initiation of immunosuppressive therapy, renal function worsened, and kidney replacement therapy was required.
Discussion
Proteinuria in AAV is typically non-nephrotic (1–3 g/day) and reflects both glomerular and tubular injury. AAV without albuminuria, especially with necrotizing and crescenteric GN, is rare. The initial differential diagnosis for this patient’s AKI included septic ATN, pre-renal injury, or obstruction due to staghorn calculus. A serologic workup was performed when the AKI failed to improve with supportive measures and the kidney biopsy was performed due to the positive MPO ANCA. This case highlights the importance of reconsidering the differential when the clinical course is atypical and not consistent with the presumed diagnosis. Moreover, AAV should be considered even in the absence of albuminuria. Finally, in the absence of an identifiable precipitating factor, the AIN in this case was attributed to AAV, representing an additional atypical feature of this presentation.