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Kidney Week

Abstract: FR-PO668

A Case of IgG4-RD Manifesting as Kidney Disease: Idiopathic or Lymphoproliferative Etiology?

Session Information

Category: Trainee Case Report

  • 1202 Glomerular Diseases: Immunology and Inflammation

Authors

  • Bond, Michael, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States
  • Kanwar, Yashpal S., Northwestern University, Chicago, Illinois, United States
  • Ahya, Shubha, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States
Introduction

IgG4-RD is a systemic inflammatory disorder characterized by infiltration of IgG4+ plasma cells into affected tissues. When IgG4-RD involves the kidneys it manifests most frequently as tubulointerstitial nephritis and/or membranous nephropathy. Imaging often demonstrates bilateral cortical nodular lesions.

Case Description

A 61-year-old male with hypertension presented for evaluation of elevated serum creatinine to 1.89 mg/dL. He noted NSAID use 2-4 times/week for back pain for much of the year prior, and home systolic BP readings 140-150mmHg. Additional workup revealed 378mg protein on 24-hour urine; and elevated free kappa and lambda light chains. SPEP showed hypergammaglobulinemia, with immunofixation electrophoresis negative for monoclonal bands. Bone marrow biopsy demonstrated multilineage hematopoiesis and 3% polytypic plasma cells without evidence of clonality; Congo red stain was negative for amyloid. Spine MRI showed no lytic lesions, but did identify a 2cm L thyroid nodule. PET/CT revealed markedly enlarged and hypermetabolic kidneys bilaterally. A diagnosis of plasma cell disorder was made. Renal biopsy showed severe lymphoplasmacytic tubulointerstitial disease with abundant IgG4+ plasma cells. Molecular analysis of the plasma cell infiltrate detected a clonal IgH gene rearrangement in a polyclonal background. Thyroid tissue from a left hemithyroidectomy for the above nodule was negative for IgG4, but an included adjacent lymph node was diffusely IgG4+. The patient’s serum creatinine demonstrated a stable improvement to 1.3-1.4 mg/dL since initiation of workup.

Discussion

This is an unusual presentation of an uncommon disease, IgG4-related disease. Immunohistochemical staining indicated a polytypic plasma cell infiltrate on renal biopsy, while molecular testing identified a clonal cell population with IgH gene rearrangement, raising the possibility of multiple populations of plasma cells: one polyclonal, another IgG4+, and a third that is clonal and producing paraprotein. Further workup is needed to determine the etiology.