Fibrillary Glomerulonephritis Presenting as Rapidly Progressive Renal Failure in a Young Female: A Case Report

Fibrillary glomerulonephritis or complement 3 glomerulopathy: a rare case of diffuse necrotising crescentic glomerulonephritis with C3-dominant glomerular deposition and positive DNAJB9

Fibrillary glomerulonephritis (FGN) and complement 3 glomerulopathy (C3G) are rare forms of glomerulonephritis with distinct aetiologies. Both FGN and C3G can present with nephritic syndrome. FGN is associated with autoimmune disease, dysproteinaemia, malignancy and hepatitis C infection. C3G is caused by the unregulated activation of the alternative complement pathway. We present a rare case of diffuse necrotising crescentic glomerulonephritis with dominant C3 glomerular staining on immunofluorescence-consistent with C3G-but electron microscopy (EM) findings of randomly oriented fibrils with a mean diameter of 14 nm and positive immunohistochemistry for DNAJB9-suggestive of FGN. To the best of our knowledge, this is the first reported case of FGN to show dominant C3 glomerular deposits. This case report reaffirms the utility of EM in the evaluation of nephritic syndrome and highlights the value of DNAJB9-a novel biomarker with a sensitivity and specificity near 100% for FGN.

Fibrillary Glomerulonephritis and DnaJ Homolog Subfamily B Member 9 (DNAJB9)

Fibrillary GN (FGN) is a rare glomerular disease that is diagnosed based on the presence of fibrils in glomeruli. The fibrils are typically noncongophilic, randomly oriented, and measure 12–24 nm. Traditionally, electron microscopy (EM) has been an important tool to aid in the diagnosis of FGN by identifying the fibrils and to distinguish it from other entities that could mimic FGN. However, recently DnaJ homolog subfamily B member 9 (DNAJB9) has emerged as both a specific and sensitive biomarker in patients with FGN. It allows prompt diagnosis and alleviates reliance on EM. DNAJB9 is a cochaperone of heat shock protein 70 and is involved in endoplasmic reticulum protein-folding pathways. But its role in the pathogenesis of FGN remains elusive. DNAJB9 may act as a putative antigen or alternatively it may secondarily bind to misfolded IgG in the glomeruli. These hypotheses need future studies to elucidate the role of DNAJB9 in the pathogenesis of FGN. The treatment regimen for FGN has been limited due to paucity of studies. Most patients receive combination immunosuppressive regimens. Rituximab has been studied the most in FGN and it may delay disease progression. Prognosis of FGN remains poor and 50% require dialysis within 2 years of diagnosis. Despite its poor prognosis in native kidneys, the rate of recurrence post-transplantation is low (20%) and patient as well as allograft outcomes are similar to patients without FGN.

Rapidly progressive glomerulonephritis due to coexistent anti-glomerular basement membrane disease and fibrillary glomerulonephritis

Anti-glomerular basement membrane (anti-GBM) disease is a major cause of rapidly progressive glomerulonephritis (RPGN). On the other hand, fibrillary glomerulonephritis (GN) typically presents as proteinuria, hematuria and renal insufficiency, but rarely as RPGN. Without electron microscopy, the diagnosis of fibrillary GN can be missed. We report a 68-year-old white woman who presented with RPGN with kidney biopsy demonstrating diffuse crescentic GN on light microscopy. By immunofluorescence, there was bright linear staining of the GBMs and smudgy mesangial staining for immunoglobulin G, C3, and kappa and lambda light chain. Electron microscopy revealed fibrillary deposits in the GBM and mesangium. A serum test for anti-GBM antibody was positive. To our knowledge, this is the first report of coexistence of fibrillary GN in a patient with anti-GBM disease. Electron microscopy is critical to identify the coexistence of other GN in patients presenting with crescentic GN.

Long-term kidney disease outcomes in fibrillary glomerulonephritis: a case series of 27 patients

BACKGROUND

Fibrillary glomerulonephritis (GN) is a rare disorder with poor renal prognosis. Therapeutic strategies, particularly the use of immunosuppressive drugs, are debated.

STUDY DESIGN

Case series.

SETTING & PARTICIPANTS

27 adults with fibrillary GN referred to 15 nephrology departments in France between 1990 and 2011 were included. All patients were given renin-angiotensin system blockers and 13 received immunosuppressive therapy, including rituximab (7 patients) and cyclophosphamide (3 patients).

OUTCOMES & MEASUREMENTS

Clinical and histologic features of patients and kidney disease outcome. Renal response was defined as a >50% decrease in 24-hour proteinuria with <15% decline in estimated glomerular filtration rate (eGFR).

RESULTS

All patients presented with proteinuria, associated with nephrotic syndrome (41%), hematuria (73%), and hypertension (70%). Baseline median eGFR was 49 mL/min/1.73 m(2). Eight patients had a history of autoimmune disease and none had evidence of hematologic malignancy during follow-up. Light microscopic studies showed mesangial GN (70%), predominant pattern of membranous GN (19%), or membranoproliferative GN (11%). By immunofluorescence, immunoglobulin G (IgG) deposits (IgG4, 15/15; IgG1, 9/15) were polyclonal in 25 cases. Serum IgG subclass distribution was normal in the 6 patients tested. After a median 46-month follow-up, renal response occurred in 6 of 13 patients who received immunosuppressive therapy with rituximab (5 patients) or cyclophosphamide (1 patient). Of these, 5 had a mesangial or membranous light microscopic pattern, and median eGFR before therapy was 76 mL/min/1.73 m(2). In contrast, chronic kidney disease progressed in 12 of 14 patients who were not given immunosuppressive therapy, 10 of whom reached end-stage renal disease.

LIMITATIONS

Number of patients, retrospective study, use of multiple immunosuppressive regimens.

CONCLUSIONS

The therapeutic approach in fibrillary GN remains challenging. The place of immunosuppressive therapy, particularly anti-B-cell agents, needs to be assessed in larger collaborative studies.

Fibrillary glomerulonephritis and renal failure in a child with systemic lupus erythematosus

Fibrillary glomerulonephritis (FGN) is a rare immune-mediated glomerulopathy characterized by randomly arranged immunoglobulin (Ig) deposits on electron microscopy. Only seven pediatric cases have been reported, and the incidence in adults is about 1.5%. A 12-year-old boy presented with systemic lupus erythematosus (SLE) with World Health Organization Class IV lupus nephritis. A repeat biopsy carried out due to a poor response to standard immunosuppressive therapy and worsening renal functions revealed diffuse proliferative glomerulonephritis with fibrillary deposits. Despite aggressive immunosuppression with plasmapheresis and rituximab, the patient developed end stage renal disease. This is an atypical pediatric case characterized by SLE-associated FGN and a poor prognosis.

Fibrillary glomerulonephritis with small fibrils in a patient with the antiphospholipid antibody syndrome successfully treated with immunosuppressive therapy

BACKGROUND

Fibrillary glomerulonephritis is a rare cause of progressive renal dysfunction, often leading to the need for dialysis within a few years. The role of immunosuppressive treatment is still uncertain although this has been tried with variable success.

CASE PRESENTATION

A 56 year old woman with the antiphospholipid antibody syndrome (IgM anticardiolipin antibodies) was seen in the nephrology clinic with haematuria, proteinuria, and worsening renal function. A renal biopsy demonstrated a mesangial proliferative glomerulonephritis on light microscopy and smaller fibrils (10.6-13.8 nm in diameter) than is usual for fibrillary glomerulonephritis (typically 18-22 nm) on electron microscopy. Amyloidosis was excluded following detailed evaluation. On account of rapidly worsening renal failure she was started on cyclophosphamide and prednisolone which led to the partial recovery and stabilization of her renal function.

CONCLUSION

This case highlights the need for routine electron microscopy in native renal biopsies, where the differential diagnosis is wide and varied and the light and immunofluorescence microscopic findings may be non specific.