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Kidney Week

Abstract: PO2210

The Histopathologic Spectrum of Kidney Biopsies in Patients with Thymoma, Myasthenia Gravis, or Both: A Report of 24 Cases from a Single Institution

Session Information

  • Onco-Nephrology - 2
    October 22, 2020 | Location: On-Demand
    Abstract Time: 10:00 AM - 12:00 PM

Category: Trainee Case Report

  • 1500 Onco-Nephrology

Authors

  • Takahashi, Akira, Cedars-Sinai Medical Center, Los Angeles, California, United States
  • Miyauchi, Takamasa, Cedars-Sinai Medical Center, Los Angeles, California, United States
  • Tatsumoto, Narihito, Cedars-Sinai Medical Center, Los Angeles, California, United States
  • Yamashita, Michifumi, Cedars-Sinai Medical Center, Los Angeles, California, United States
Introduction

Nephropathy in patients (Pts) with thymic diseases such as thymoma and myasthenia gravis (MG) is rare and has been the subject of case reports. Previously, 93 cases have been reported from multiple institutions, and of these, common diseases are minimal change disease (MCD; 45.2 %), membranous nephropathy (MN; 19.4 %), and primary focal segmental glomerulosclerosis (FSGS; 9.7 %). Here we characterize the spectrum of kidney biopsy findings in 24 cases from a single institution.

Case Description

Total 40,268 renal biopsy cases from 2005 through 2019 at Cedars-Sinai Medical Center were reviewed. 24 cases (0.0596 %) of Pts have history of thymoma and/or MG. Main pathological diagnoses are following: MCD (10 cases; 41.7%), Tubulointerstitial nephritis (TIN; 3 cases; 12.5 %), Immune complex-mediated glomerulonephritis (IC-GN; 2 cases; 8.3 %), Diabetic glomerulosclerosis (2 cases; 8.3 %), acute tubular injury/necrosis (ATI/ATN) with myoglobin casts (2 cases; 8.3 %), ATI/ATN (1 case; 4.2 %), IgA nephropathy (1 case; 4.2 %), MN (1 case; 4.2 %), secondary FSGS (1 case; 4.2 %), and Monoclonal Ig deposition disease (1 case; 4.2 %).

Discussion

Consistent with the previous reports, MCD is the most common renal lesion in Pts with thymic diseases. However, we experienced only one case of MN and no primary FSGS, the 2nd and 3rd common diseases in the reports. We, instead, observed kidney diseases that haven’t been reported before: TIN, and ATI/ATN with myoglobin casts. Of 3 TIN cases, 1 showed granulomatous interstitial inflammation without infection; and 1 case showed acute tubulitis with immune complex deposits both in mesangium and along tubular basement membranes. In addition, 40 % of MCD cases showed an atypical feature: IC deposits in mesangial area. The possible mechanisms of thymic disease-associated nephropathy include T cell dysregulation, IC formation containing tumor antigen, and effects of tumor-releasing lymphokines. In conclusion, this is the largest and unique case series of nephropathy in Pts with thymic disease from a single institution.