# Monoclonal Gammopathy of Renal Significance in a Patient With Cryoglobulinemia and Nephrotic Syndrome: A Case Report

## TL;DR

A 65-year-old woman with kidney issues and abnormal proteins in her blood was diagnosed with a rare condition called MGRS and showed improvement after treatment.

## Contribution

This case report presents a rare presentation of IgM kappa-related MGRS with type I cryoglobulinemia.

## Key findings

- The patient exhibited symptoms of nephrotic syndrome and cryoglobulinemia with no evidence of malignancy.
- Kidney biopsy confirmed membranoproliferative glomerulonephritis with cryoglobulin deposition and vasculitis.
- Treatment with rituximab and corticosteroids led to complete resolution of symptoms.

## Abstract

We report a case of monoclonal gammopathy of renal significance (MGRS) in a 65-year-old female patient who presented to the emergency department with uncontrolled hypertension, generalized edema, abdominal distension, and frothy urine. Apart from recently diagnosed hypertension, she had no significant comorbidities. Examination revealed periorbital swelling, bibasal crackles, moderate ascites, and bilateral lower limb pitting edema. Laboratory findings showed proteinuria, low complement levels, elevated IgM, decreased IgG, and the presence of cryoglobulins. Imaging and PET-CT ruled out malignancy. Kidney biopsy revealed membranoproliferative glomerulonephritis with cryoglobulin deposition and vasculitis. Bone marrow biopsy confirmed plasma cell dyscrasia with kappa light chain restriction. Despite suspicion of Waldenström macroglobulinemia or IgM myeloma, cytogenetics and fluorescence in situ hybridization were negative. The patient was treated with rituximab and corticosteroids, with complete resolution of ascites, edema, and proteinuria. This case highlights an uncommon presentation of IgM kappa-related MGRS with type I cryoglobulinemia.