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Kidney Week

Abstract: TH-PO555

Rare Case of IgG4-Related Kidney Pseudotumor

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

  • Cui, Shengjie, Indiana University School of Medicine , Indianapolis, Indiana, United States
  • Phillips, Carrie L., Indiana University School of Medicine , Indianapolis, Indiana, United States
  • Sundaram, Chandru, Indiana University School of Medicine, Indianapolis, Indiana, United States
  • Saeed, Omer Abdelaziz mohammed, Indiana University School of Medicine , Indianapolis, Indiana, United States
Introduction

Immunoglobulin G4-related disease (IgG4-RD) is a chronic fibroinflammatory condition that can involve one or multiple organs in the body. It is characterized by tissue lymphoplasmacytic infiltration with IgG4+ plasma cells, storiform fibrosis, and possibly elevated serum IgG4 levels. Renal involvement by IgG4-RD is rare and can be confused with kidney neoplasms as it has the tendency to form pseudotumor.

Case Description

A 40-year-old woman complained of abdominal pain for three months. Abdominal CT and MRI scan revealed an enhancing lesion in the lower pole cortex of the left kidney measuring 2.7 x 2.4 x 2.2 cm. The lesion showed central necrosis with thick enhancing wall and it was minimally exophytic without violation of Gerota's fascia. There were also stable borderline and enlarged retroperitoneal lymph nodes. Kidney function tests including eGFR, BUN, and serum creatinine were normal. The patient’s preliminary diagnosis was renal cell carcinoma and partial nephrectomy was performed. Gross examination showed a 2 X 2 X 1.3 cm white, firm poorly circumscribed irregular lesion with no evidence of necrosis or hemorrhage. Microscopic examination showed large areas of storiform fibrosis with intense lymphoplasmacytic infiltrate and vascular involvement. Immunohistochemical stains showed increased IgG4+ plasma cells (>25 cells/HPF). The IgG4+: IgG+ plasma cell ratio was 50%.

Discussion

IgG4-RKD is the term used to describe multiple kidney lesions including tubulointerstitial nephritis, renal pyelitis, or renal insufficiency as a result of retroperitoneal fibrosis. CT scan of patients with IgG4 tubulointerstitial nephritis usually reveals multiple low density parenchymal lesions. The presence of a solitary lesion with exophytic appearance is rare. In these circumstances, it is usually very difficult to rule out a neoplastic process based on imaging alone. Steroids are the first-line treatment in most patients. A high clinical suspicion, serum IgG4, and a representative biopsy are usually sufficient to make the diagnosis in most cases. Awareness about the unusual instances where imaging studies are worrisome for malignancy can help avoid unnecessary surgery.