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Abstract: PO1960

Anti-Glomerular Basement Membrane (GBM) Disease with Atypical Clinical and Histologic Features Precipitated by Parainfluenza

Session Information

Category: Trainee Case Report

  • 1203 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • Fouhy, Fergal, Cork University Hosptial, Cork, Ireland
  • Burke, Louise M., Cork University Hosptial, Cork, Ireland
  • Mayer, Nick, Cork University Hosptial, Cork, Ireland
  • O'Shaughnessy, Michelle M., Cork University Hosptial, Cork, Ireland
Introduction

Anti-GBM disease typically presents with rapidly progressive glomerulonephritis (RPGN) and linear GBM staining for IgG1 or IgG3. We describe a case of anti-GBM disease with an initially indolent course that progressed to RPGN following parainfluenza infection. Serum anti-GBM antibodies were only mildly elevated and kidney biopsy showed linear GBM staining for IgG4.

Case Description

An otherwise healthy 23-year old male presented with a 2-week history of cough, dyspnea, and hemoptysis. He recently returned from China, where he smoked tobacco heavily. Hematuria and proteinuria were noted during a routine medical exam 2 months prior. Physical exam notable for BP 150/90mmHg, bibasilar chest crackles, and bipedal edema. Investigations: sCr 2.6mg/dL (1.5mg/dL 2 weeks prior); 3+blood and 3+protein by UA; negative/normal C3, C4, ANA, anti-dsDNA, ANCA; viral respiratory PCR positive for parainfluenza; serum anti-GBM 15u/ml (nl <10u/ml). CT Thorax showed bilateral pleural effusions and groundglass nodularity within the right middle and lower lobes. Kidney biopsy showed linear GBM staining for IgG4, wtih glomerular necrosis, crescents, and unusually prominent endocapillary proliferation (Figure).

Treatment included diuretics, antibiotics, IV methylprednisolone, oral cyclophosphamide, and 8 plasma exchanges over 11 days. Serum anti-GBM was undetectable after 2 days. He progressed to dialysis-requiring ESRD over the next 6 weeks: a repeat kidney biopsy showed peristent crescentic GN with endocapillary proliferation and strong linear IgG4 staining, despite repeatedly negative serum anti-GBM.

Discussion

This case highlights complexities in the pathogenesis and diagnosis of anti-GBM disease. RPGN was likely triggered by parainfluenza infection, a rarely described association. Low anti-GBM antibody levels were likely explained by the poor sensitivity of ELISA to detect IgG4. Finally, prominent endocapillary proliferation is characteristic of "atypical anti-GBM disease", yet serum anti-GBM was positive in this case.