Abstract: TH-PO950
Congophillic Fibrillary Glomerulonephritis: A Diagnostic Challenge
Session Information
- Glomerular Trainee Case Reports
November 07, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Trainee Case Report
- 1202 Glomerular Diseases: Immunology and Inflammation
Authors
- Wijeratne, Viduranga, Gosford Hospital, Gosford, New South Wales, Australia
- Shingde, Meena, ICPMR Westmead Hospital, NSW Pathology, Westmead, New South Wales, Australia
- Renthawa, Jasveen K., ICPMR Westmead Hospital, NSW Pathology, Westmead, New South Wales, Australia
- Kumar, Subramanian K., Gosford Nephrology, Terrigal, New South Wales, Australia
Introduction
Fibrillary glomerulonephritis is characterised by the presence of randomly orientated nonbranching fibrils larger than those found in amyloid and lack the histochemical staining of amyloid. The absence of Congo Red reactivity has traditionally been a defining feature to differentiate it from amyloid glomerulopathy. We examined two cases showing the existence of Congophillic fibrillary glomerulopathy.
Case Description
Case 1: A 67 year old man presented with peripheral oedema and subnephrotic proteinuria on a background of poorly controlled hypertension. Initial renal biopsy suggested a focal segmental glomerulosclerosis with 13.9 nm fibrils on electron microscopy in the previous year. Despite treatment with rituximab, cyclosporin and cyclophosphamide, there was ongoing proteinuria with repeat renal biopsy showing Congo Red positive staining with 15.9 nm fibrils present. A monoclonal gammopathy of uncertain significance with IgM lambda was found.
Case 2: A 51 year old man presented with newly diagnosed diabetes and was found to have subnephrotic proteinuria and microscopic haematuria. He underwent a renal biopsy finding Congo Red positive deposits with ultrastructural findings of 20 nm fibrils. Subsequent screening for malignancy and lymphoproliferative disease were negative. Despite immunosuppression with rituximab, cyclophosphamide and prednisone, the patient continues to have ongoing proteinuria.
Discussion
These two cases highlight the importance of recognising cases of Congophillic fibrillary glomerulonephritis which represents both a diagnostic and management challenge. Differentiating the renally-limited from the systemic immunoglobulin related amyloidosis is crucial to prevent misdiagnosis and inappropriate treatments such as the chemotherapy used to treat amyloid or immunotactoid glomerulopathy. Careful analysis of the ultrastructural characteristics combined with mass spectrometry and the use of novel biomarkers such as DnaJ homolog subfamily B member 9 (DNAJB9) could help discern such cases of Congophillic fibrillary glomerulonephritis.