DNAJB9 Staining is Equally Distributed in Monoclonal and Polyclonal Fibrillary Glomerulopathies

Document Type

Conference Proceeding

Publication Date

11-2025

Publication Title

American Journal of Clinical Pathology

Abstract

Introduction/Objective: Fibrillary glomerulopathy (GN) is composed of fibrils twice thicker than that of amyloidosis but stains negatively for Congo red; two characteristics which are sufficient to distinguish from amyloidosis traditionally. Although DNAJB9 has been used as marker to specifically identify fibrillary glomerulopathy, it is not well established if DNAJB9 can help distinguish monoclonal variants of fibrillary GN from polyclonal variants of fibrillary GN. This study aimed to determine if monoclonal variants and polyclonal variants of fibrillary GN can be separated by different pattens of DNAJB9 staining. Methods/Case Report: Four cases of monoclonal fibrillary glomerulopathies and four cases of polyclonal fibrillary glomerulopathies were included for the comparison of DNAJB9 staining by immunohistochemical method. In addition, 10 potential negative controls were also stained for DNAJB9. Results: Patients’ ages ranged from 35 to 76 years old with more female patients than male patients. Both monoclonal fibrillary GN and poly - clonal fibrillary GN showed similar 2-3+ mesangial/intramembranous DNAJB9 stains in all glomeruli of each case without apparent differences. No DNAJB9 staining was seen in vessels or proximal tubules, but weak staining was occasionally seen in distal tubular cytoplasm. The glomeruli and other renal structures of negative control cases, including 3 amyloidosis and other variants of glomerulopathies, stained negatively for DNAJB9. Conclusion: Our data indicates that DNAJB9 is a reliable biomarker to rule out non-fibrillary GN cases including amyloidosis, but this stain cannot differentiate the monoclonal fibrillary GN from the polyclonal fibrillary GN. The findings also support the view that DNAJB9 may be an autoantigen that can attract the binding of polyclonal immunocomplex or monoclonal Ig and monoclonal light chains.

Volume

164

Issue

Suppl 1

First Page

S116

Comments

American Society for Clinical Pathology (ASCP) Annual Meeting, November 17-20, 2025, Atlanta, GA

Last Page

S117

DOI

10.1093/ajcp/aqaf121.284

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