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Abstract: PO1573

Proliferative Glomerulonephritis in a Patient with NK Cell Lymphocytosis

Session Information

Category: Glomerular Diseases

  • 1203 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • Angle, Hannah, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, United States
  • Yi, Jia, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, United States
  • Jain, Koyal, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, United States
Introduction

Monoclonal gammopathy of renal significance (MGRS) occurs in patients with non-malignant lymphoproliferative disorders who present with kidney injury secondary to monoclonal immunoglobulin deposition.1 We present a rare case of proliferative glomerulonephritis (PGN) likely due to NK cell lymphocytosis.

Case Description

A 57-year-old male with NK lymphocytosis and HTN presented with progressively worsening oliguric renal failure (creatinine 1.1 to 6.2 mg/dL over 3 months) and elevated lambda free light chains (FLC) with a κ/λ ratio of 0.06 (κ=3.14, λ=52.58). Urine sediment showed numerous dysmorphic RBCs and granular casts. Renal biopsy (limited specimen) revealed PGN with polyclonal-IgG-dominant deposition and background of moderate interstitial fibrosis and tubular atrophy. Although obvious monoclonal lesions were absent and the PGN may have been coincidental, there was concern for a potential paraneoplastic GN induced by NK lymphocytosis or, less likely, MGRS. Thus, patient was treated with Cyclophosphamide-Bortezomib-Dexamethasone (CyBorD). However, due to worsening kidney function patient was started on hemodialysis, hoping for potential renal recovery. Despite significant hematologic response (plasma cell burden <1%), chemotherapy was discontinued after 7 months due to lack of renal improvement and worsening medication side effects.

Discussion

This case suggests a potential rare cause of PGN with polyclonal-IgG-dominant deposition due to NK cell lymphocytosis. This is the first case to describe a potential association between them. Additionally, while the patient did have a hematologic response to the CyBorD, there was no renal recovery. Although the PGN may have been coincidental, CyBorD therapy should have had some effect while treating PGN. This suggests a potentially aggressive form of the disease resulting in end-stage kidney disease within 3 months in our patient. It also brings up the question of whether it was the presence of NK cell lymphocytosis that worsened the renal prognosis. Such cases are extremely difficult to treat and likely have a poor prognosis.
Reference: Leung, N., et al. The evaluation of monoclonal gammopathy of renal significance: a consensus report of the International Kidney and Monoclonal Gammopathy Research Group. Nat Rev Nephrol 15, 45–59 (2019). https://doi.org/10.1038/s41581-018-0077-4