Case Report
Copyright ©The Author(s) 2024. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Clin Cases. Jun 16, 2024; 12(17): 3200-3205
Published online Jun 16, 2024. doi: 10.12998/wjcc.v12.i17.3200
Congophilic fibrils in the glomeruli with polyclonal immunoglobulin gamma staining - another cause for diagnostic overlap: A case report
Maria Bernadette Che-Ying Chow, Lucas Bushrow, Irmeen Siddiqui, April Chiu, Mirza Hamirani, Anjali A Satoskar
Maria Bernadette Che-Ying Chow, Lucas Bushrow, Irmeen Siddiqui, Anjali A Satoskar, Department of Pathology, The Ohio State University Medical Center, Columbus, OH 43210, United States
Maria Bernadette Che-Ying Chow, Department of Pathology, North District Hospital, Sheung Shui, Hong Kong, China
April Chiu, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, United States
Mirza Hamirani, Department of Internal Medicine, S. Joseph's Hospital, Parkersburg, WV 26101, United States
Author contributions: Chow MBCY drafted and revised the manuscript; Bushrow L helped draft the manuscript; Siddiqui I helped with serum immunofixation results; Chiu A provided mass spectrometry result and Figure 2; Hamirani H provided clinical follow-up and obtained patient consent; Satoskar AA conceptualized and the idea and implemented the collaborative effort, drafted and revised the manuscript, and provided immunofluorescence images.
Informed consent statement: Study participant provided informed written consent prior to study.
Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article.
CARE Checklist (2016) statement: The authors have read the CARE Checklist (2016), and the manuscript was prepared and revised according to the CARE Checklist (2016).
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Anjali A Satoskar, MD, Professor, Department of Pathology, The Ohio State University Medical Center, B073 Graves Hall 333 W 10th Ave, Columbus, OH 43210, United States. anjali.satoskar@osumc.edu
Received: February 6, 2024
Revised: March 15, 2024
Accepted: April 23, 2024
Published online: June 16, 2024
Processing time: 118 Days and 16.2 Hours
Abstract
BACKGROUND

Glomerulopathy with fibrillary deposits is not uncommon in routine nephropathology practice, with amyloidosis and fibrillary glomerulonephritis being the two most frequently encountered entities. Renal amyloid heavy and light chain (AHL) is relatively uncommon and its biopsy diagnosis is usually limited to cases that show strong equivalent staining for a single immunoglobulin (Ig) heavy chain and a single light chain, further supported by mass spectrometry (MS) and serum studies for monoclonal protein. But polyclonal light chain staining can pose a challenge.

CASE SUMMARY

Herein we present a challenging case of renal AHL with polyclonal and polytypic Ig gamma (IgG) staining pattern by immunofluorescence. The patient is a 62-year-old Caucasian male who presented to an outside institution with a serum creatinine of up to 8.1 mg/dL and nephrotic range proteinuria. Despite the finding of a polyclonal and polytypic staining pattern on immunofluorescence, ultrastructural study of the renal biopsy demonstrated the presence of fibrils with a mean diameter of 10 nm. Congo red was positive while DNAJB9 was negative. MS suggested a diagnosis of amyloid AHL type with IgG and lambda, but kappa light chains were also present supporting the immunofluorescence staining results. Serum immunofixation studies demonstrated IgG lambda monoclonal spike. The patient was started on chemotherapy. The chronic renal injury however was quite advanced and he ended up needing dialysis shortly after.

CONCLUSION

Tissue diagnosis of AHL amyloid can be tricky. Thorough confirmation using other available diagnostic techniques is recommended in such cases.

Keywords: Heavy and light chain amyloid; Fibrillary glomerulonephritis; DNAJB9; Serum immunofixation; Protein electrophoresis; Mass spectrometry; Congo red; Case report

Core Tip: Amyloidosis and fibrillary glomerulonephritis are the two most commonly encountered glomerulopathies with fibrillary deposits. Accurate diagnosis and differentiation between these two entities are important for patient management. Furthermore, accurate subtyping is also required for amyloidosis cases to further guide treatment. This case report highlights an uncommon diagnostic pitfall that a nephropathologist may encounter while distinguishing light and heavy chain amyloid from fibrillary glomerulopathy. The possible underlying mechanisms are discussed, and we reiterate the importance of a clinical-pathological correlation and the use of multiple available diagnostic modalities if needed, particularly for these overlapping diagnostic entities.