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Abstract: PO1815

A Case with Immunotactoid Glomerulonephritis with Masked Monoclonal Light-Chain Deposition Disease

Session Information

Category: Trainee Case Report

  • 1202 Glomerular Diseases: Immunology and Inflammation

Author

  • Postalcioglu, Merve, Kent Hospital, Warwick, Rhode Island, United States
Introduction

The immunotactoid glomerulonephritis (ITG) is a rare disorder that is characterized by proteinuria, hematuria, hypertension, and kidney failure. Its diagnosis and timely treatment are important in order to decrease morbidity, conserve kidney function, and improve survival.

Case Description

An 82-year old man with a past medical history of uncontrolled hypertension and cerebrovascular disease presented with myalgia, profound weakness and persistent vomiting for 9 days. In the emergency department, his vital signs were significant for blood pressure 220/109 mmHg. BMP revealed creatinine as 3.48 mg/dl, which was 0.9 mg/dl at baseline. The patient was diagnosed with hypertensive urgency and acute kidney injury. Urinalysis showed 107/HPF red blood cells and protein >500 mg/dl. Spot urine albumin/creatinine ratio was 869.9 mg/g. Serum C3 decreased to 29.5 mg/dl (reference: 88-201) and C4 decreased to 2.5 mg/dl (reference: 16-47). Hepatitis B and C were non-reactive. Kidney biopsy was planned and pulse dose steroid, 500 mg IV daily, was prescribed for 3 days. The patient’s kidney function continued to worsen and he required hemodialysis. His serum free kappa level elevated to 4.54 mg/dl (reference 0.33-1.54), lambda level was normal 2.54 mg/dl (reference 0.57-2.63), free kappa/lambda ratio elevated to 1.80 (normal 0.26-1.65). Serum immunofixation study showed IgG kappa monoclonal ab without M-spike; urine protein electrophoresis showed elevated protein level with no apparent M-spike. Initially, kidney biopsy suggested proliferative glomerulonephritis with C3 deposits with light-microscopy. However, repeat immunofluorescence was consistent with diffuse proliferative immunotactoid glomerulonephritis with "masked" monoclonal IgG1-kappa deposits. Congo red stain was negative, ruling out amyloidosis. The patient was continued on daily high-dose steroid treatment. He was referred to Hematology/Oncology for bone marrow biopsy for concern of plasma cell neoplasm or lymphoproliferative disorder. Dialysis was discontinued at the time of discharge as patient’s kidney function improved with steroid treatment.

Discussion

It is important to keep ITG in the differential diagnosis as high-dose steroid or cyclophosphamide might prevent rapid glomerulonephritis progression. Treatment of underlying disease such as light-chain deposition disease might have some benefit on renal disease.