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Kidney Week

Abstract: PO1753

Granulomatosis with Polyangiitis and Acute Tubulointerstitial Nephritis in the Absence of Glomerulonephritis

Session Information

Category: Trainee Case Report

  • 1202 Glomerular Diseases: Immunology and Inflammation

Authors

  • Guo, Weiwen, Singapore General Hospital, Singapore, Singapore
  • Lim, Cynthia Ciwei, Singapore General Hospital, Singapore, Singapore
  • Choo Chon Jun, Jason, Singapore General Hospital, Singapore, Singapore
Introduction

Isolated TIN in the absence of glomerular involvement is uncommon in ANCA-associated vasculitis(AAV).

Case Description

77 year old female with normal renal function presented with acute kidney injury (AKI) with peak SCr 482 µmol/L and required dialysis. She received antibiotics for sinusitis and pneumonia 2 weeks prior. Urinalysis noted iso-morphic RBCs and proteinuria of 2g/24hours. Anti-proteinase3(PR3) antibody was positive at 114U/ml. Anti-nuclear,anti-dsDNA and anti-GBM antibodies were negative. Bronchoalveolar lavage was negative for alveolar hemorrhage. Kidney biopsy revealed minor glomerular abnormalities and acute TIN with interstitial non-necrotising granuloma and multinucleated giant cells. Ziehl-Neelsen stain was negative. Immunofluorescence, electron microscopy were non-contributory.

She was treated for possible drug-induced interstitial nephritis with oral prednisolone 0.6mg/kg and therapy was rapidly tapered due to cytomegalovirus infection. She was on prednisolone 5mg daily by 3 months. SCr improved to 174µmol/L and anti-PR3 was 4.4U/ml.

A year later, she presented with episcleritis, fever, weight loss and AKI. SCr was 399µmol/L with glomerular hematuria and proteinuria. Patient refused a repeat biopsy but in view of AKI with concurrent rise in the anti-PR3 antibody at 95.1U/ml, she was diagnosed with PR3-ANCA granulomatosis with polyangiitis (GPA) and treated with cyclophosphamide, prednisolone and dialysis.

Discussion

Our patient had PR3-ANCA GPA that presented with isolated granulomatous TIN without glomerulonephritis. Rapid improvement in renal function after low-dose prednisolone monotherapy was consistent with treatment response for TIN.
In AAV, isolated TIN may be caused by vasculitis of the peritubular capillaries . Most cases of AAV with isolated acute TIN improved with no treatment or prednisolone monotherapy.
Thus, it is important to recognize that isolated acute TIN is an unusual presentation for AAV.