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Abstract: FR-PO694

Early-Stage IgG4-Related Tubulointerstitial Nephritis Incidentally Detected with a Tumor Lesion of the Ureteropelvic Junction

Session Information

Category: Trainee Case Report

  • 1602 Pathology and Lab Medicine: Clinical

Authors

  • Miyanaga, Tatsuhito, Kanazawa University Hospital, Kanazawa, Ishikawa, Japan
  • Hara, Satoshi, Kanazawa University Hospital, Kanazawa, Ishikawa, Japan
  • Zoshima, Takeshi, Kanazawa University Hospital, Kanazawa, Ishikawa, Japan
  • Nishioka, Ryo, Kanazawa University Hospital, Kanazawa, Ishikawa, Japan
  • Ito, Kiyoaki, Kanazawa University Hospital, Kanazawa, Ishikawa, Japan
  • Mizushima, Ichiro, Kanazawa University Hospital, Kanazawa, Ishikawa, Japan
  • Fujii, Hiroshi, Kanazawa University Hospital, Kanazawa, Ishikawa, Japan
  • Sato, Yuki, Department of Nephrology, Kyoto University Graduate School of Medicine, Kyoto, Japan
  • Yanagita, Motoko, Department of Nephrology, Kyoto University Graduate School of Medicine, Kyoto, Japan
  • Kawano, Mitsuhiro, Kanazawa University Hospital, Kanazawa, Ishikawa, Japan

Group or Team Name

  • Department of Rheumatology, Kanazawa University Hospital, Kanazawa, Japan
Introduction

Histological examination of IgG4-related kidney disease (IgG4-RKD) is typically performed when kidney function decreases or when multiple low-density lesions are found in enhanced computed tomography (CT) images; thus, advanced-phase rather than early-phase IgG4-TIN is often detected. Here, we report a case of very early-stage IgG4-related tubulointerstitial nephritis (TIN) incidentally detected with involvement of the ureteropelvic junction (UPJ).

Case Description

A 72-year-old Japanese man was admitted to our hospital for progressive renal dysfunction. He had been followed-up for 18 years after surgical resection of a bladder tumor. Six months prior to presenting at our hospital, periodic CT showed a mass lesion on his right UPJ. He was clinically diagnosed with right ureter cancer and received neoadjuvant therapy followed by a right nephroureterectomy. Histology revealed IgG4-positive cell (IgG4+PC) infiltration, obliterative phlebitis, and storiform fibrosis in the removed mass, leading to the diagnosis of IgG4-RKD. Notably, IgG4+PCs also infiltrated the tubulointerstitium of the cortex of the right kidney without storiform fibrosis, although no imaging abnormality was viewed in preoperative CT, indicative of very early-phase IgG4-TIN. In addition, mononuclear cells gathered only beneath the kidney capsule and around arteries and veins, and based on immunofluorescence, most of these aggregations were composed of T cells, B cells, and CD21-positive follicular dendritic cells, suggestive of mature tertiary lymphoid tissue (TLT). IgG4+PCs surrounded the TLT. Because renal function gradually worsened, the patient was admitted. Although neither extra-renal organ involvement nor an imaging abnormality of the left kidney was noted, glucocorticoids were initiated and prevented renal deterioration, suggesting that IgG4-TIN was also present in the left kidney.

Discussion

IgG4-TIN was incidentally detected with involvement of the UPJ regardless of a lack of abnormalities in images of the kidney. IgG4+PC was distributed beneath the kidney capsule and around arteries and veins accompanying TLT. This case suggests that IgG4-TIN develops from common sites of TLT with TLT formation prior to the appearance of imaging abnormalities.