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Kidney Week

Abstract: PO1912

Lymphomatous Infiltration of the Kidney in a Patient with Waldenstrom Macroglobulinemia

Session Information

Category: Onco-Nephrology

  • 1500 Onco-Nephrology

Authors

  • Ravipati, Prasanth, University of Minnesota Twin Cities, Minneapolis, Minnesota, United States
  • Bu, Lihong, University of Minnesota Twin Cities, Minneapolis, Minnesota, United States
  • Sachs, Zohar, University of Minnesota Twin Cities, Minneapolis, Minnesota, United States
  • Nachman, Patrick H., University of Minnesota Twin Cities, Minneapolis, Minnesota, United States
Introduction

Kidney disease can be an initial presentation or a chronic manifestation of plasma cell dyscrasias. The aim of this case report is to illuminate a rare presentation of kidney disease driven by lymphomatous infiltration of the kidney in a patient with Waldenstrom’s Macroglobulinemia (WM).

Case Description

A 70 year old female with an 8 year history of WM (IgM, kappa) was referred for declining renal function. Four months prior to presentation, she had stable WM disease activity and was without symptoms of worsening disease burden. In November of 2020, she was hospitalized with SARS-CoV-2 infection with respiratory failure and acute kidney injury (AKI). Her serum creatinine (sCr) peaked at 3.7 mg/dL from a baseline of 0.9 mg/dL, but recovered to a sCr of 1.1 mg/dL by the time of discharge. Two months after discharge, her renal function began to decline prompting nephrology referral. Her sCr had risen to 1.9 mg/dL and she had new onset proteinuria of 1.5 g/day. A kidney biopsy showed lymphomatous infiltration of the tubulointerstitium without glomerular involvement. Immunofluorescence microscopy showed strong IgM and kappa stain but minimal lambda stain. Immunohistochemistry showed heavy interstitial staining for CD20 + B cells, and the presence of CD138 + plasma cells. Treatment with rituximab and bendamustine resulted in an improvement in renal function (sCr 1.4 mg/dL).

Discussion

WM is an uncommon hematologic malignancy, and extramedullary involvement is rare. Only 7% of a cohort of patients with WM who underwent kidney biopsy had lymphomatous infiltration of the kidney [Higgins et al., CJASN 2018]. In our case, the differential diagnosis was broad given the patient's modest proteinuria and kidney dysfunction in the context of recent AKI and hospitalization. Considerations included paraprotein related disease, medication related interstitial nephritis, or possibly an undefined sequela of SARS-CoV-2 infection. This case emphasizes the importance of surveillance for kidney dysfunction in patients with plasma cell dyscrasias, even if patients appear to have stable lymphoproliferative disease. Additionally, the effects of SARS-CoV-2 infection in patients with indolent lymphomas is unknown, but it is noteworthy that our patient developed lymphomatous kidney involvement after initial recovery of AKI in the setting of SARS-CoV-2 infection.