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Kidney Week

Abstract: TH-PO700

An Unusual Presentation of a Common Disease: Primary Membranous Glomerulopathy with Light-Chain Deposits: Case Report

Session Information

Category: Glomerular Diseases

  • 1402 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • Moreno, Rodolfo Alejandro, Centro Medico Militar, Guatemala, Guatemala, Guatemala
  • Navarro Blackaller, Guillermo, Hospital Civil de Guadalajara Unidad Hospitalaria Fray Antonio Alcalde, Guadalajara, Jalisco, Mexico
  • De león, Werner, SERPAT, Guatemala, Guatemala, Guatemala
  • Armas, David Alejandro, Centro Medico Militar, Guatemala, Guatemala, Guatemala
Introduction

Membranous glomerulopathy (MG) is a common cause of nephrotic syndrome (NS) caused by the formation of immune complexes along the subepithelial slope of the glomerular basement membrane (GBM) and considered as the main cause of idiopathic NS in adults. Deposits of light chain isotype are rarely seen.

Case Description

A 56-year-old Guatemalan male patient with a 3-month history of lower-limbs edema. No previous medical history. On first evaluation presented AKI with SCr of 1.58mg/dl associated with proteinuria (12.8gr/day), hematuria (5 RBC/HPF) and oval fatty bodies and fat droplets. Laboratories with hyperlipidemia (cholesterol 692mg/dl, triglycerides 396mg/dl), C3-C4 normal, FANA+ 1:80, ANCAs, HIV, HBV, HCV, rheumatoid factor were negatives and serum anti-PLA2R+ (353 RU/ml (positive >20)), serum and urine electrophoresis negative for monoclonal protein. Kidney biopsy was performed and reported homogenous thickening of the GBM with mesangial proliferation; Jones stain with pin hole pattern on the capillary wall. Negative for endocapillary or extra capillary hypercellularity, double contours or interstitial fibrosis IF: IgG (+), IgM (+), Kappa (++) and PLA2R (++) with granular pattern in GBM. The patient is on RAASi with losartan 100mg/day while decides to accept rituximab protocol. With improvement of SCr (1.04mg/dl) controls after 1-month but still with nephrotic range proteinuria.

Discussion

The pathophysiology of MG results from the formation of immune complexes, predominantly by polytypic deposits along the subepithelial slope of the GBM. Usually, these immune complexes are against PLA2R and HTSD7A but about 10% of patients with typical PMN are negative for both antibodies making it probable that more autoantibodies to podocyte antigens will be found such as light-chain deposits. Though, positive serum antiPLA2R suggest a primary etiology, the rarely seen deposition of single IgG subclass should prompt a clinical workup to exclude the presence of an underlying etiology.