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Abstract: TH-PO542

Thymic Disease-Associated Nephropathy: A Report of 21 Cases from a Single Institution

Session Information

  • Trainee Case Reports - I
    October 25, 2018 | Location: Exhibit Hall, San Diego Convention Center
    Abstract Time: 10:00 AM - 12:00 PM

Category: Trainee Case Reports

  • 1502 Pathology and Lab Medicine: Clinical

Authors

  • 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 with thymic diseases such as thymoma and myasthenia gravis (MG) is rare. Previously, 69 cases have been reported from multiple institutions, and of these, common diseases are minimal change disease (MCD; 56.5%), membranous nephropathy (MN; 20.3%), and focal segmental glomerulosclerosis (FSGS; 17.4%). Here we characterize the spectrum of new 21 renal disease cases associated with thymic disease from a single hospital.

Case Description

Total 36,562 renal biopsy cases from 2005 through mid 2018 were reviewed at Cedars-Sinai Medical Center. 21 cases (0.057%) of patients have history of thymoma and/or MG. Pathological diagnoses are following: MCD (9 cases; 42.9%), Immune complex-mediated glomerulonephritis (IC-GN; 4 cases; 19.0%), FSGS (2 cases; 9.5%), IgA nephropathy (IgAN; 2 cases; 9.5%), acute tubular injury/necrosis (ATI/ATN) with myoglobin casts (2 cases; 9.5%), and acute interstitial nephritis (AIN; 2 cases; 9.5%).

Discussion

Consistent to the previous reports, MCD is the most common renal lesion in patients with thymic diseases. However, we did not observed MN, the second most common disease in the reports. We, instead, observed 4 cases of IC-GN that did not fit to MN: 2 showed mild IC-GN superimposing on MCD; 1 showed lupus nephritis-like GN (ISN/RPS CLASS II) without proliferative features; and 1 showed lupus nephritis-like GN (CLASS II) with segmental membranous change. We also experienced kidney diseases that haven't been reported before as an association with thymic disease: IgAN, ATI/ATN with myoglobin casts, and AIN. 2 cases of IgAN were low-grade without hypercellularity (endocapillary hypercellularity or crescents). 2 cases of ATI/ATN with myoglobin casts showed multiple myoglobin-positive tubular casts. Of AIN cases, one showed mild tubulitis with mild immune complex deposits both in mesangium and along tubular basement membranes. Another case showed granulomatous AIN. In conclusion, this is the largest and unique case series of nephropathy in patients with thymic disease from a single institution.

Summary