Kidney Week

Abstract: TH-PO816

Proliferative Glomerulonephritis with Monoclonal IgG1λ Deposits, Characterized by Intracapillary λ-Containing Macrophages Infiltration

Session Information

• Pathology and Lab Medicine - I
  November 02, 2023 | Location: Exhibit Hall, Pennsylvania Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Pathology and Lab Medicine

• 1800 Pathology and Lab Medicine

Authors

• Kasahara, Natsumi, Kanazawa Daigaku Fuzoku Byoin, Kanazawa, Ishikawa, Japan

Natsumi Kasahara,

• Nishioka, Ryo, Kanazawa Daigaku Fuzoku Byoin, Kanazawa, Ishikawa, Japan

Ryo Nishioka,

• Kaikoi, Daichi, Toyama Kenritsu Chuo Byoin, Toyama, Toyama, Japan

Daichi Kaikoi,

• Mori, Anri, Kanazawa Daigaku Fuzoku Byoin, Kanazawa, Ishikawa, Japan

Anri Mori,

• Akamatsu, Hiromitsu, Kanazawa Daigaku Fuzoku Byoin, Kanazawa, Ishikawa, Japan

Hiromitsu Akamatsu,

• Saito, Hiroaki, Kanazawa Daigaku Fuzoku Byoin, Kanazawa, Ishikawa, Japan

Hiroaki Saito,

• Sanada, Hajime, Kanazawa Daigaku Fuzoku Byoin, Kanazawa, Ishikawa, Japan

Hajime Sanada,

• Takahashi, Yoshinori, Kanazawa Daigaku Fuzoku Byoin, Kanazawa, Ishikawa, Japan

Yoshinori Takahashi,

• Tsuge, Shunsuke, Kanazawa Daigaku Fuzoku Byoin, Kanazawa, Ishikawa, Japan

Shunsuke Tsuge,

• Hara, Satoshi, Kanazawa Daigaku Fuzoku Byoin, Kanazawa, Ishikawa, Japan

Satoshi Hara,

• Ito, Kiyoaki, Kanazawa Daigaku Fuzoku Byoin, Kanazawa, Ishikawa, Japan

Kiyoaki Ito,

• Mizushima, Ichiro, Kanazawa Daigaku Fuzoku Byoin, Kanazawa, Ishikawa, Japan

Ichiro Mizushima,

• Kawano, Mitsuhiro, Kanazawa Daigaku Fuzoku Byoin, Kanazawa, Ishikawa, Japan

Mitsuhiro Kawano,

Introduction

Monoclonal gammopathy of renal significance (MGRS) encompasses kidney disorders caused by monoclonal proteins. We report a rare case of proliferative glomerulonephritis with monoclonal IgG1λ deposits (PGNMID) in a patient with monoclonal gammopathy of undetermined significance (MGUS). Notably, the case is characterized by the infiltration of intracapillary macrophages containing λ immunoglobulin.

Case Description

A 69-year-old Japanese female with MGUS presented with renal dysfunction and proteinuria. She had a history of persistent proteinuria (urinary protein 3.4 g/g Creatinine), microscopic hematuria, and kidney dysfunction (serum Creatinine 1.3 mg/dL) for the past 2 years. Due to refractory symptoms, she was admitted to our hospital. On admission, her urinary protein was 1.1 g/day, with microscopic hematuria, and serum Creatinine 1.9 mg/dL. Immunofixation analysis detected monoclonal IgGλ in both serum and urine, while cryoglobulins were absent. Renal biopsy revealed diffuse endocapillary proliferative glomerulonephritis with subendothelial deposition. Immunofluorescence demonstrated IgG1, C3, and λ deposition with an infringe pattern, confirming the diagnosis of PGNMID. Remarkably, the intracapillary cells exhibited a foamy appearance and showed double positivity for CD68 and λ. Electron microscopy confirmed electron dense deposits (EDD) in the subendothelial area, and intracapillary foam cells contained EDD. Due to the presence of other life-threatening factors, the patient received renal protection therapy without anti-tumor treatment. Over a four-year period, renal dysfunction progressively worsened, with a serum creatinine level of 2.9 mg/dL and persistent proteinuria.

Discussion

We present a rare case of PGNMID characterized by the infiltration of intracapillary monoclonal λ-containing macrophages. The underlying pathophysiology remains unknown, but it may share similarities with crystal-soring histiocytosis, where macrophages engulf monoclonal immunoglobulins. To our knowledge, only one similar case has been previously, suggesting that this histological finding could represent a novel manifestation of MGRS.