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Abstract: PO1866

Hypocomplementemic Urticarial Vasculitis: Interstitial Nephritis with New Microtubular Deposits and Successful Response to Rituximab

Session Information

Category: Trainee Case Report

  • 1203 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • Dossaji, Adam, Baystate Medical Center, Springfield, Massachusetts, United States
  • Hodgins, Spencer, Baystate Medical Center, Springfield, Massachusetts, United States
  • Landry, Daniel L., Baystate Medical Center, Springfield, Massachusetts, United States
  • Crisi, Giovanna M., Baystate Medical Center, Springfield, Massachusetts, United States
  • Pawlak, Sara Ann, Baystate Medical Center, Springfield, Massachusetts, United States
  • Braden, Gregory Lee, Baystate Medical Center, Springfield, Massachusetts, United States
Introduction

HUV is caused by antibodies to C1q complement and has many features of systemic lupus and cryoglobulinemia. Different patterns of GN often occur such as the mesangial GN, MPGN or membranous GN but interstitial nephritis has never been described.

Case Description

A 57 year old female in 2007 developed recurrent hives, angioedema, leucocytoclastic vasculitis on skin biopsy & 5 g proteinuria with RBC casts. C1q complement was 2 mg/dL, C3 20 mg/dL, C4 6 mg/dL & C1q antibody was 35 mg/mL (NL<10). All other serology and cryos were negative. Serum creatinine was 0.6mg/dL. Her 1st renal biopsy showed mesangial proliferative GN with +3 IF for IgG, IgA, C1q & EM deposits in the mesangial , subendothelial, subepithelial locations & interstitial inflammation. Parallel microtubular structures, 25 nm wide with hollow cores, were present in interstitial capillaries and hilar arterioles but not in the glomeruli. Tubular basement membranes & peritubular capillaries were +3 positive for IgG & C1q with granular deposits on EM. She failed prednisone, mycophenolate & cyclosporin, but after 4 weekly doses of Rituximab 375 mg/m2 she rapidly went into remission within 2 months which was sustained for 6 years.
HUV flared in 2016 with new onset nephrotic syndrome, hives, angioedema, COPD & AKI. Serum creatinine was 2.2 mg/dL & urine total protein/creatinine ratio was 8.7 with RBC casts. C1q was 4 mg/dL, C3 38 mg/dL, C4 4 mg/dL & C1q antibody > 100 mg/ml. A 2nd renal biopsy showed diffuse endocapillary proliferation with membranous GN similar to lupus Class IV &V and interstitial inflammation. IF was +3 for IgG, IgA, C1q and kappa and lambda in the same locations as biopsy 1. Tubules & peritubular capillaries were positive for IgG & C1q, peritubular capillaries had 25 nm hollow microtubule structures as before. Rituximab was initiated at 375 mg/m2 for 4 doses. It induced a complete renal remission after 3 months with a serum creatinine of 0.6 mg/dL & urine total protein of 210 mg.

Discussion

We conclude: In addition to glomerulonephritis HUV can cause interstitial nephritis with +IF for IgG & C1q. HUV causes unique microtubular structures in the interstitium but not the glomeruli. Rituximab rapidly induces clinical renal remission in HUV.