Kidney Week

Abstract: SA-PO704

Monoclonal IgG Deposit on Tubular Basement Membrane in Original Kidney

Session Information

• Pathology and Lab Medicine: Clinical
  November 09, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Pathology and Lab Medicine

• 1602 Pathology and Lab Medicine: Clinical

Authors

• Sawada, Anri, Nippon Medical University, Tokyo, Japan

Anri Sawada,

• Okumi, Masayoshi, Tokyo Women's Medical University, Tokyo, Japan

Masayoshi Okumi,

• Taneda, Sekiko, Tokyo Women's Medical University, Tokyo, Japan

Sekiko Taneda,

• Fuchinoue, Shohei, Tokyo Women's Medical University, Tokyo, Japan

Shohei Fuchinoue,

• Ishida, Hideki, Tokyo Women's Medical University, Tokyo, Japan

Hideki Ishida,

• Hattori, Motoshi, Tokyo Women's Medical University, Tokyo, Japan

Motoshi Hattori,

• Tanabe, Kazunari, Tokyo Women's Medical University, Tokyo, Japan

Kazunari Tanabe,

• Honda, Kazuho, Showa University School of Medicine, Tokyo, Japan

Kazuho Honda,

• Nitta, Kosaku, Tokyo Women's Medical University, Tokyo, Japan

Kosaku Nitta,

• Koike, Junki, St. Marianna University, Kawasaki, Japan

Junki Koike,

• Nagashima, Yoji, Tokyo Women's Medical University, Tokyo, Japan

Yoji Nagashima,

• Shimizu, Akira, Nippon Medical University, Tokyo, Japan

Akira Shimizu,

Background

Tubular basement membrane immune deposit (TBMID) are often observed during renal biopsies. We recently reported that monoclonal IgG TBMID is associated with the progression of interstitial fibrosis and tubular atrophy (IFTA) in renal allografts; however, its significance in original kidneys remains unclear.

Methods

This retrospective study includes 3,126 patients who underwent native renal biopsy and 1,724 patients who underwent 0-hour biopsy between 2008 and 2018 at Tokyo Women’s Medical University. We performed light microscopic, electron microscopic, and immunofluorescence studies.

Results

IgG TBMID was identified in 164 (5.2%) patients who had undergone native renal biopsy and in six (0.4%) patients who underwent 0-hour biopsy. The IgG subclass was identified in 94 patients. Monoclonal IgG TBMID was found in seven patients, including three patients who underwent 0-hour biopsy. Pathological diagnosis was that of IgA nephropathy (n = 3, including one patient who underwent of 0-hour biopsy), minor glomerular abnormalities (n = 2), antineutrophil cytoplasmic antibody-related vasculitis (n = 1), and light and heavy chain deposition disease (LHCDD) (n = 1). Upon IF, glomerular IgG deposition was negative for all patients. The combinations of IgG subclass and light chain were IgG1κ (n = 2), IgG1λ (n = 3), and IgG2κ (n = 2). Complement C3, C4, and C1q staining in the tubular basement membrane (TBM) was negative for all patients. Upon electron microscopy (EM), all patients showed a powdery electron-dense deposition (EDD). Median IFTA was 5% (range: 0–30%). Based on bone marrow examination, the diagnosis of monoclonal gammopathy of undetermined significance was made in one patient, which was different from the patient with LHCDD. Median follow-up period from biopsy was 3.5 (range: 0.5–6) years. Although one patient with LHCDD developed renal graft failure, all other patients had stable renal function.

Conclusion

Unlike cases of renal allograft, IgG TBMID in the original kidneys does not appear to be associated with renal prognosis. However, it is necessary to investigate for hematological disorders and evaluate the type of deposit in the TBM by EM.