Clinical and pathologic features of fibrillary glomerulonephritis

Updates on the Diagnosis and Management of Fibrillary Glomerulonephritis

Fibrillary glomerulonephritis (FGN) is a rare kidney disease typically affecting individuals in middle age, frequently presenting with advanced renal failure, proteinuria, and hypertension. FGN can be associated with autoimmune diseases, hepatitis C infection, and malignancies. Its exact pathogenesis remains elusive, and the exact role of DnaJ homolog subfamily B member 9 is yet to be determined. On renal biopsy, FGN exhibits distinctive Congo-red-negative, nonbranching fibrils, approximately 20 nm in diameter. DnaJ homolog subfamily B member 9 immunohistochemical staining has become a gold standard for diagnosis. Atypical variants exist, including congophilic, monotypic, and crescentic FGN, highlighting the disease's heterogeneity. Treatment with immunosuppression, including rituximab, has shown variable success, with no standard therapy established. FGN often leads to end-stage kidney disease, with a median progression time of 2-4 years postdiagnosis. Kidney transplantation is a viable option for FGN-related end-stage kidney disease, but recurrence in transplanted kidneys is not rare.

[Fibrillary glomerulonephritis]

Fibrillary glomerulonephritis (FGN) is a glomerular disease described since 1977, with a prevalence in renal biopsies of less than 1%. It presents as renal failure, proteinuria, haematuria and hypertension in middle-aged adults. It is defined histologically, using light microscopy, which reveals organised deposits of fibrils measuring around 20nm, which are negative for Congo red staining. Electron microscopy, the first gold standard for diagnosis, has now been superseded by immunohistochemistry using the anti-DNAJB9 antibody. The discovery of this molecule has revolutionised the diagnosis of GNF, thanks to its excellent sensitivity and specificity (98% and 99% respectively). The association of GNF with hepatitis C virus, autoimmune diseases, neoplasia or haemopathy is debated. Renal prognosis is guarded, with 50% of patients progressing to end-stage renal failure within 2 to 4years of diagnosis. In the absence of randomised controlled trials, the recommended treatment is based on nephroprotective measures, corticosteroid therapy and possibly a second-line immunosuppressant such as rituximab. After renal transplantation, recovery or recurrence is possible. The pathophysiology of the disease is still poorly understood, and further studies are needed.

Ultrastructural Examination of Glomerular Fibrillary Deposits in Diabetic Nephropathy

Glomerular fibrillary deposits have occasionally been reported in diabetic nephropathy, but no large-scale, ultrastructural evaluation of these deposits has been reported so far. Here, we report our study of glomerular non-Congophilic, DnaJ homolog subfamily B member 9 negative fibrillary deposits in diabetic nephropathy as characterized by transmission electron microscopy. Clinical data from 55 patients with biopsy-confirmed diabetic nephropathy and 18 healthy living donors were reviewed, and their biopsies were evaluated by light microscopy, immunofluorescence, and electron microscopy. Small fibrillary structures with a diameter of 10 ± 1 nm were present in all cases with diabetic nephropathy, regardless of the histologic class. In addition, glomerular fibrillary structures with a diameter of 23 ± 5 nm or 30 ± 7 nm were present in 35 cases. Interestingly, especially the small- and medium-sized fibrils, usually without apparent organization, were comparable with fibrils in fibrillary glomerulopathy. We conclude that glomerular fibrillary deposits occur far more commonly in renal biopsies of patients with diabetic nephropathy than generally considered. This is an important finding because their similarity to fibrils in fibrillary glomerulonephritis may complicate the histologic diagnostic process, especially in cases of overlapping clinical manifestations. Therefore, when encountering fibrillary deposits on electron microscopy, it is important to consider diabetic nephropathy as an alternative diagnosis.

Immunofluorescence Staining for IgG Subclass: Cause for Discrepancy in the Detection of IgG1

Introduction

Immunofluorescence (IF) staining for IgG subclasses plays an important role in the classification of kidney disease. However, widely used IgG subclass-specific antibodies are now commercially unavailable. Thus, we compared alternative antibodies for performing IgG subclass staining.

Methods

A total of 21 cases were stained by 3 different methods: direct IF using fluorescein isothiocyanate (FITC)-conjugated polyclonal antibodies against IgG1-4 (commercially unavailable method), direct IF using FITC-conjugated monoclonal antibodies (clones HP-6091, 6014, 6050, and 6025), indirect IF using monoclonal antibodies (clones HP-6069, 6002, 6050, and 6025), and FITC-conjugated polyclonal secondary antibody. For cases with discrepancy in IgG1 staining, additional direct IF using FITC-conjugated monoclonal antibody (clone 4E3) was performed.

Results

Of 21 cases, 11 (52%) had no staining for IgG1 by direct IF using the clone HP-6091 despite ≥1+ staining by the direct IF using polyclonal antibodies. Similarly, direct IF for IgG1 using the clone 4E3 had negative result in all 10 cases with available tissue. However, indirect IF for IgG1 using the clone HP-6069 had similar staining intensity (within 1 order of magnitude) as direct IF using the polyclonal antibodies (10 of 10). Results of IF for IgG2, IgG3, and IgG4 were similar in most cases.

Conclusion

The choice of antibodies influences the result of IgG subclass staining, especially for anti-IgG1 antibodies, in which 2 monoclonal antibodies (HP6091 and 4E3) appear less sensitive. Although this may be due to unaccounted variables and requires confirmation, our results may partially explain the difference in IgG1 staining in the literature and underscore the need for careful validation.

DNAJB9 Fibrillary Glomerulonephritis With Membranous-Like Pattern: A Case-Based Literature Review

Fibrillary glomerulonephritis (FGN) is a rare immune-mediated glomerular disease traditionally characterized by the presence of amyloid-like, randomly aligned, fibrillary deposits in the capillary wall, measuring approximately 20 nm in diameter and composed of polyclonal IgG. FGN is usually a primary disease with no pathognomonic clinical or laboratory findings. More than that, on light microscopic evaluation, it can receive various histological patterns, rendering its diagnosis indistinguishable. However, the identification by immunohistochemistry of a novel biomarker, DNA-J heat-shock protein family member B9 (DNAJB9), has created a new era in FGN diagnosis even in the absence of electron microscopy. Typically, most patients manifest various degrees of renal insufficiency, hypertension, microscopic hematuria, proteinuria, and occasionally frank nephrotic syndrome. The prognosis is usually severe and progression to end-stage kidney disease (ESKD) is the rule, given that no specific treatment is available until now, despite the fact that in small studies rituximab-based therapy seems to alleviate the severity and improve the disease progression. Herein, we report the case of a 63-year-old Caucasian man presenting with uncontrolled hypertension, headache, shortness of breath, and lower limb edema. Diagnostic evaluation revealed mild deterioration of kidney function, nephrotic range proteinuria, and faint IgGκ monoclonal bands in serum and urine immunofixation. After negative meticulous investigation for secondary nephrotic syndrome causes, the patient underwent a kidney biopsy. Biopsy sample showed two glomeruli with mesangial expansion and thickened glomerular basement membrane (GBM) on light microscopy, a pattern masquerading as membranous nephropathy stage III-IV, while IgG and C3 were 1-2+ on GBM and mesangium in immunofluorescence. Thickened GBM with fibrils on electron microscopy were found, while DNAJB9 in immunohistochemistry was positive, confirming FGN. Once diagnosis of FGN was made, a combination of steroids with rituximab was initiated while the patient was receiving the standard anti-hypertensive therapy, simultaneously with a sodium-glucose cotransporter-2 (SGLT2) inhibitor. The 12-month follow-up showed approximately 85% decrease in proteinuria alongside stabilization of kidney function and blood pressure normalization. Hence, in this article, we aim to highlight that DNAJB9-associated FGN may mimic membranous glomerulopathy stage III-IV on light microscopy, especially when a small kidney sample with extensive involvement by fibrils of GBM is examined. Moreover, we underscore the fact that ultramicroscopic examination is of crucial importance in the differential diagnosis of glomerular deposition diseases and that DNAJB9 identification on immunohistochemistry consists of a revolutionary and robust biomarker in FGN diagnosis.

Fibrillar glomerulonephritis in a patient with systemic lupus erythematosus with no evidence of lupus nephritis

Fibrillar glomerulonephritis (FGN) is a rare proliferative form of glomerular disease characterised by randomly oriented fibrillar deposits with a mean diameter of 20 nm. It has a rare association with systemic lupus erythematosus (SLE). We report the case of a female in her mid-50's with a 20 year history of SLE, who developed proteinuria due to FGN and had no histological evidence of lupus nephritis. She was maintained on azathioprine and prednisolone. A renal biopsy revealed randomly arranged fibrillar deposits that positively stained for DNAJB9, consistent with a diagnosis of FGN. Azathioprine was switched to mycophenolate mofetil, and the patient showed significant improvement in proteinuria. This case-based review describes the diagnosis, management and clinical outcome of FGN in association with SLE in the absence of lupus nephritis.

Hepatitis Virus C-associated Nephropathy: A Review and Update

Hepatitis C virus (HCV) infection causes hepatic and extrahepatic organ involvement. Chronic kidney disease (CKD) is a prevalent non-communicable disorder, accounting for significant morbidity and mortality worldwide. Acute kidney injury and CKD are not uncommon sequels of acute or chronic HCV infection.

The pathogenesis of HCV-associated kidney injuries is not well explored. Excess cryoglobulin production occurs in HCV infection. The cryoglobulin may initiate immune complex-mediated vasculitis, inducing vascular thrombosis and inflammation due to cryoglobulin deposits.

Furthermore, direct damage to nephron parts also occurs in HCV patients. Other contributory causes such as hypertension, diabetes, and genetic polymorphism enhance the risk of kidney damage in HCV-infected individuals. Implementing CKD prevention, regular evaluation, and therapy may improve the HCV burden of kidney damage and its related outcomes.

Therefore, in this review, we discuss and update the possible mechanism(s) of kidney injury pathogenesis with HCV infection. We searched for related published articles in EMBASE, Google Scholar, Google, PubMed, and Scopus. We used various texts and phrases, including hepatitis virus and kidney, HCV and CKD, kidney pathology in viral hepatitis, kidney transplantation in HCV-infected patients, kidney allograft survival in viral hepatitis patients, mechanism of kidney pathology in viral hepatitis, dialysis and viral hepatitis, HCV infection and kidney injuries, and viral hepatitis and CKD progression, etc. to identify relevant articles.

Fibrillary Glomerulonephritis: A Great Mimicker of Rapidly Progressive Glomerulonephritis

Fibrillary glomerulonephritis (FGN) is a rare but severe kidney disease found to have non-amyloid fibrillary deposits in the mesangium and/or glomerular capillary wall. It was initially thought to be idiopathic, but recent studies show an association with autoimmune disease, malignancy, and hepatitis C infection. We report a case of a non-diabetic patient presenting with long-standing microscopic hematuria, progressive proteinuria, hypertension, and worsening kidney function. The kidney biopsy demonstrated subepithelial fibrillar deposits of size 17 mm randomly oriented with one partial cellular crescent on electron microscopy. Direct immunofluorescence showed no staining for IgG or light chains. It was weakly positive for Congo red staining with a slightly higher serum free kappa/lambda light chain ratio, but serum immunofixation showed no monoclonal protein detection. We empirically treated with rituximab but with no clear benefit or no renal recovery and eventually started on hemodialysis. FGN has an extremely poor prognosis with very few treatment options available. We report this case to emphasize the need for larger, multi-center studies for treatment approaches with collaborating and consolidating data from case reports and case series due to the rarity of the disease.

Characteristics and renal survival of patients with lupus nephritis with glomerular immunoglobulin G4 deposition: a single-centre retrospective analysis

OBJECTIVE

Renal injury is common in SLE. Immune complex deposition plays an important role in the development of lupus nephritis (LN), while little is known about glomerular IgG₄ deposition in patients with LN. This study aimed to investigate the characteristics and renal outcome of patients with LN with glomerular IgG₄ deposition.

METHODS

This is a single-centre retrospective study enrolling 89 patients with biopsy-proven LN. Clinicopathological features, treatment responses and renal outcomes were collected and compared between patients with and without glomerular IgG₄ deposition. Renal outcome events include progression of renal dysfunction and end-stage renal disease.

RESULTS

Thirty (33.7%) patients had glomerular IgG₄ deposition. Patients with glomerular IgG₄ deposition had lower serum albumin level (25.06±8.61 g/L vs 28.29±6.31 g/L, p=0.05), more class V LN (60.0% vs 35.6%, p=0.03), more positive phospholipase A2 receptor (PLA2R) staining (43.3% vs 18.6%, p=0.01), more IgG₁ deposits (96.7% vs 64.4%, p=0.01) and less C3 deposits (46.7% vs 72.9%, p=0.02) than those without glomerular IgG₄ deposition. They also had better renal survival than those without glomerular IgG₄ deposition (96.7% vs 79.7%, p=0.03). Multivariate Cox regression showed that high serum creatinine level (relative risk (RR)=1.005, 95% CI 1.002 to 1.008, p=0.01) and high Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) scores (RR=1.078, 95% CI 1.004 to 1.157, p=0.04) independently correlated with poor renal outcome, while glomerular IgG₄ deposition tended to correlate with good renal outcome (RR=5.95, 95% CI 0.759 to 45.97, p=0.09). Further, patients with both glomerular IgG₄ and PLA2R positivity (n=13) had higher levels of serum C3 and C4 and less glomerular C3 deposits compared with those with positive IgG₄ but negative PLA2R in the glomerulus (n=17), and had a tendency of low SLEDAI score (p=0.07).

CONCLUSIONS

Patients with LN with glomerular IgG₄ deposits may have better renal survival, and patients with LN with simultaneous glomerular IgG₄ and PLA2R deposits may have low disease activity.

Clinicopathologic features and treatment outcomes of patients with fibrillary glomerulonephritis: A case series

ABSTRACT

Fibrillary glomerulonephritis (FGN) is a diverse glomerular disease with poor renal prognosis. The optimal therapeutic approach remains undetermined, as treatment outcomes vary across different studies.We retrospectively reviewed the medical data of 10 patients diagnosed with biopsy-proven FGN at our center between 2004 and 2019. Clinical and histological features, as well as therapeutic regimens and treatment response, are reported.The patients were predominantly men (2.5/1 men-female ratio) with a mean age at diagnosis of 46.5 years (IQR: 41.5-59.5). The median proteinuria and creatinine levels at presentation were 2.55 g/day (IQR: 0.4-8.9) and 1.35 mg/dl (IQR: 0.94-1.88), respectively. Four out of 10 patients presented with nephrotic syndrome, 5 patients with nephritic syndrome and 1 with isolated microscopic hematuria. Light microscopy showed mesangial proliferative (n = 7), membranoproliferative-like (n = 2), and diffuse sclerosing patterns (n = 1). Rituximab was used in 7/10 patients, either as monotherapy (n = 3) or combined with cyclophosphamide and corticosteroids (n = 4). Patients who were treated with immunosuppression had higher median levels of creatinine (1.40 mg/dl) and proteinuria (3.5 g/d) compared to those who received supportive treatment alone (0.94 mg/dl and 0.6 g/d, respectively). After a median follow-up of 30 months (IQR:18-66.5), 4 out of 7 patients (57%) treated with immunosuppression achieved a clinical response, 1 had persistent renal dysfunction and 2 patients progressed to end-stage renal disease.The present case series extends the existing literature on the clinical features and outcomes of FGN, as well as the use of rituximab-based regimens for the treatment of the disease. Further research is needed to establish the proper management of the disease.

A Fresh Perspective on Monoclonal Gammopathies of Renal Significance

Monoclonal gammopathies of renal significance (MGRS) encompass a remarkable variety of kidney diseases that result from intrinsic nephrotoxic properties of certain monoclonal Igs or their subunits. Effective disease-modifying treatments rely on the targeting of a malignant B-cell clone that may be demonstrable but often is quite hypothetical. Hence, convincing arguments for the genuine monoclonal character of the causative mono-isotypic Ig tissue deposits is needed for design of appropriate treatment strategies. The purpose of this article was to critically analyze distinct situations of suspected MGRS that occur in the practice of pathologists, nephrologists, hematologists, and immunologists. A particular focus of interest is the group of conditions known as proliferative glomerulonephritis with mono-isotypic immunoglobulin deposits (PGNMIDs), which illustrates the difficulties and ambiguities surrounding a definitive assignment of MGRS status.

DNA J homolog subfamily B member 9 and other advances in fibrillary glomerulonephritis

PURPOSE OF REVIEW

Fibrillary glomerulonephritis (FGN) involves ∼1% of native kidney biopsies and is characterized by glomerular deposition of fibrils larger than amyloid (12-24 nm diameter) composed of polyclonal immunoglobulin G (IgG). The recent discovery of DNA J homolog subfamily B member 9 (DNAJB9) in FGN glomerular deposits has contributed a specific and sensitive biomarker, informing morphologic classification and pathogenesis. This review will consider contemporary FGN incidence and genetics, pathogenesis, (lack of) paraprotein association, variants, treatment, and transplantation.

RECENT FINDINGS

DNAJB9 tissue assays have enabled the identification of morphologic variants and improved classification of fibrillary-like glomerular diseases. Together with paraffin immunofluorescence and IgG subclass studies, these have established that FGN is only rarely monoclonal and these patients usually do not have an monoclonal gammopathy. The discovery of DNAJB9 opens new avenues of investigation into FGN pathogenesis, especially those of the unfolded protein response. Treatment for FGN remains empiric, with some encouraging data on rituximab-based therapy. Transplantation is a good option for patients progressing to end-stage kidney disease.

SUMMARY

Advances building on the discovery of DNAJB9 in FGN should lead to long-term evolution in targeted treatment and outcome of this glomerular disease.

Treatment of fibrillary glomerulonephritis with rituximab: a 12-month pilot study

BACKGROUND

Fibrillary glomerulonephritis (FGN) is a rare type of glomerulonephritis with poor prognosis, with no known effective therapies available for treatment. The objective of the study was to evaluate the efficacy and safety of rituximab in treatment of patients with FGN and to investigate the effect of rituximab on DNAJB9 levels.

METHODS

This was a pilot prospective clinical trial in which patients with idiopathic FGN were treated with two courses of rituximab (1 g each) 2 weeks apart at the beginning and then again at 6 months. Primary outcome was defined as preservation of kidney function at 12 months with stable or increased creatinine clearance. Secondary outcome was defined as achieving complete remission (CR) defined as proteinuria <300 mg/24 h or partial remission (PR) with proteinuria <3 g/24 h and at least 50% reduction in the proteinuria. DNAJB9 levels were also measured in the serum at baseline, 6 and 12 months.

RESULTS

The creatinine clearance did not change significantly during this time, from 47.7 mL/min/1.73 m2 at baseline to 43.7 mL/min/1.73 m2 during follow-up (P = 0.15). Proteinuria declined from 4.43 (1.6-5.53) g/24 h at baseline to 1.9 (0.46-5.26) g/24 h at 12 months but did not reach significance (P = 0.06). None of the patients reached CR, and 3 of the 11 achieved PR. There was no change in the DNAJB9 levels following treatment with rituximab. The most common adverse event was nasal congestion, fatigue and muscle cramps.

CONCLUSIONS

Treatment of patients with two courses of rituximab over a span of 6 months was associated with stabilization of renal function but did not result in a significant change in proteinuria and with no change in the DNAJB9 levels.

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.

Renal amyloidosis with emphasis on the diagnostic role of electron microscopy

Our understanding of renal diseases with structured deposits has improved in the last two decades with the development of new diagnostic techniques that also changed the role of ultrastructural pathology in diagnostic decision-making. This review article addresses the current role of electron microscopy in the evaluation of structured deposits and discusses the impact of new developments. The diagnosis in a subset of structured deposits, amyloidosis, relies on morphologic and tinctorial characteristics at the light microscopic level. Congo red staining of tissue with demonstrable birefringence upon polarization has been regarded as the mainstay during tissue evaluation; however, there are pitfalls that must be considered, and electron microscopy remains a crucial adjunct investigative tool. Ultrastructurally the amyloid fibrils are unique with their characteristic appearance. They are randomly arranged, rigid, criss-crossing, non-branching, 7-15 nm (0.07-0.15 um) in diameter and of variable length. The morphology of fibrils is very similar in the different types of amyloidosis. By scanning electron microscopy amyloid fibrils appear artfully displayed. Immunofluorescence and immunohistochemical stains can be used to characterize the type of amyloidosis while mass spectroscopy is extremely useful in cases where typing of the amyloid using the above-mentioned techniques is difficult or equivocal.

Immunoglobulin-Negative DNAJB9-Associated Fibrillary Glomerulonephritis: A Report of 9 Cases

Fibrillary glomerulonephritis (FGN) was previously defined by glomerular deposition of haphazardly oriented fibrils that stain with antisera to immunoglobulins but do not stain with Congo red. We report what is to our knowledge the first series of immunoglobulin-negative FGN, consisting of 9 adults (7 women and 2 men) with a mean age at diagnosis of 66 years. Patients presented with proteinuria (100%; mean protein excretion, 3g/d), hematuria (100%), and elevated serum creatinine level (100%). Comorbid conditions included carcinoma in 3 and hepatitis C virus infection in 2; no patient had hypocomplementemia or monoclonal gammopathy. Histologically, glomeruli were positive for DNAJB9, showed mostly mild mesangial hypercellularity and/or sclerosis, and were negative for immunoglobulins by immunofluorescence on frozen and paraffin tissue. Ultrastructurally, randomly oriented fibrils measuring 13 to 20nm in diameter were seen intermingling with mesangial matrix in all and infiltrating glomerular basement membranes in 5. On follow-up (mean duration, 21 months), 2 had disease remission, 4 had persistently elevated serum creatinine levels and proteinuria, and 3 required kidney replacement therapy. Thus, rare cases of FGN are not associated with glomerular immunoglobulin deposition, and the diagnosis of FGN in these cases can be confirmed by DNAJB9 immunostaining. Pathogenesis remains to be elucidated.

Fibrillary glomerulonephritis presenting as crescentic glomerulonephritis in a young female: a case study

Fibrillary glomerulonephritis (FGN) is a rare disorder accounting for up to 1% of all glomerulonephritis (GN). FGN usually manifests as nephrotic or subnephrotic proteinuria, hematuria, and hypertension in patients after the sixth decade. The overall prognosis of FGN is very poor. Crescentic presentation of FGN is uncommon which may be diagnosed as rapidly progressive glomerulonephritis (RPGN) unless electron microscopy and/or special stains are done. We report a case of a young female who presented as RPGN but diagnosis was revised to crescentic FGN after electron microscopy and immunohistochemical staining with DNAJB9 stain. Patient remained dialysis-dependent after treatment with steroid and cyclophosphamide for 2 months and progressed to end-stage renal disease (ESRD). Crescentic FGN usually does not respond to treatment and invariably progresses to ESRD over few months. This case emphasizes the defining role of electron microscopy and special stains in diagnosing uncommon glomerular diseases.

Successful treatment of a unique case of congophilic fibrillary glomerulonephritis: A case report

INTRODUCTION

Amyloidosis and fibrillary glomerulonephritis (FGN) share similar electron microscopic signatures including random arrangement of fibrils. However, distinction between the 2 can often be made using Congo Red staining.

PATIENT CONCERNS

Here we describe a unique case of FGN, which stained positive for Congo Red, as well as DnaJ heat shock protein family (Hsp40) member B9 which is more specific for FGN. The patient presented with acute kidney injury and severe proteinuria.

DIAGNOSIS

Congophilic FGN.

INTERVENTIONS

Six-month course of mycophenolate mofetil and prednisone.

OUTCOMES

complete resolution of acute kidney injury and proteinuria TAKE HOME LESSONS:: To our knowledge, this is the first reported case of successful treatment of this rare condition using mycophenolate mofetil and prednisone.

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.

Recurrence of DNAJB9-Positive Fibrillary Glomerulonephritis After Kidney Transplantation: A Case Series

RATIONALE & OBJECTIVE

Fibrillary glomerulonephritis (FGN) is a rare glomerular disease that often progresses to kidney failure requiring kidney replacement therapy. We have recently identified a novel biomarker of FGN, DnaJ homolog subfamily B member 9 (DNAJB9). In this study, we used sequential protocol allograft biopsies and DNAJB9 staining to help characterize a series of patients with native kidney FGN who underwent kidney transplantation.

STUDY DESIGN

Case series.

SETTING & PARTICIPANTS

Between 1996 and 2016, kidney transplantation was performed on 19 patients with a reported diagnosis of FGN in their native/transplant kidneys. Using standard diagnostic criteria and DNAJB9 staining, we excluded 5 patients (4 atypical cases diagnosed as possible FGN and 1 donor-derived FGN). Protocol allograft biopsies had been performed at 4, 12, 24, 60, and 120 months posttransplantation. DNAJB9 immunohistochemistry was performed using an anti-DNAJB9 rabbit polyclonal antibody. Pre- and posttransplantation demographic and clinical characteristics were collected. Summary statistical analysis was performed, including nonparametric statistical tests.

OBSERVATIONS

The 14 patients with FGN had a median posttransplantation follow-up of 5.7 (IQR, 2.9-13.8) years. 3 (21%) patients had recurrence of FGN, detected on the 5- (n=1) and 10-year (n=2) allograft biopsies. Median time to recurrence was 10.2 (IQR, 5-10.5) years. Median levels of proteinuria and iothalamate clearance at the time of recurrence were 243mg/d and 56mL/min. The remaining 11 patients had no evidence of histologic recurrence on the last posttransplantation biopsy, although the median time of follow-up was significantly less at 4.4 (IQR, 2.9-14.4) years. 3 (21%) patients had a monoclonal protein detectable in serum obtained pretransplantation; none of these patients had recurrent FGN.

LIMITATIONS

Small study sample and shorter follow-up time in the nonrecurrent versus recurrent group.

CONCLUSIONS

In this series, FGN had an indolent course in the kidney allograft in that detectable histologic recurrence did not appear for at least 5 years posttransplantation.

DNAJB9-positive monotypic fibrillary glomerulonephritis is not associated with monoclonal gammopathy in the vast majority of patients

The association of fibrillary glomerulonephritis (FGN) with monoclonal gammopathy has been controversial, although monotypic FGN is currently classified as a monoclonal gammopathy of renal significance (MGRS) lesion. To define this lesion, we correlated findings by immunofluorescence on frozen and paraffin tissue, IgG subtype staining and serum protein electrophoresis with immunofixation in patients with monotypic FGN. Immunofluorescence was performed on paraffin sections from 35 cases of DNAJB9-associated FGN that showed apparent light chain restriction of glomerular IgG deposits by standard immunofluorescence on frozen tissue. On paraffin immunofluorescence, 15 cases (14 lambda and one kappa restricted cases on frozen tissue immunofluorescence) showed no light chain restriction, 19 showed similar light chain restriction, and one was negative for both light chains. Seven of the 15 cases with masked polyclonal deposits also had IgG subclass restriction and these cases would have been diagnosed as a form of monoclonal protein-associated glomerulonephritis if paraffin immunofluorescence was not performed. Monotypic FGN (confirmed by paraffin immunofluorescence and IgG subclass restriction) accounted for only one of 151 (0.7%) patients with FGN encountered during the last two years. Only one of 11 of cases had a detectable circulating monoclonal protein on serum protein electrophoresis with immunofixation. We propose that paraffin immunofluorescence is required to make the diagnosis of lambda-restricted monotypic FGN as it unmasked polytypic deposits in over half of patients. When confirmed by paraffin immunofluorescence and IgG subclass staining, DNAJB9-positive monotypic FGN is very rare and is not associated with monoclonal gammopathy in the vast majority of patients. Thus, there is a question whether this lesion should be included in MGRS-related diseases.

Fibrillary Glomerulopathy with a High Level of Myeloperoxidase-ANCA: A Case Report

An elderly woman was admitted with the chief complaint of gross hematuria. Laboratory values indicated a high myeloperoxidase-ANCA level. In renal histological examination, 40% of the glomeruli showed crescent formation, but immunofluorescence staining showed positivity for IgG, C3, and C1q. Furthermore, the deposition of fibrils in the glomerulus was noted on electron microscopy, and immunohistochemical staining showed strong positivity for DNA-J heat shock protein family member B9 (DNAJB9). Crescent formation is a common feature of fibrillary glomerulonephritis (FGN). Thus, in ANCA-positive crescentic glomerulonephritis, immunohistochemical assessments for immunoglobulins and DNAJB9, as well as electron microscopy, are important to correctly diagnose FGN.

Treatment of hepatitis C virus infection in patients with mixed cryoglobulinemic syndrome and cryoglobulinemic glomerulonephritis

Cryoglobulinemia is a common extrahepatic manifestation of infection with hepatitis C virus (HCV). When signs and symptoms of systemic vasculitis or glomerulonephritis occur in the presence of circulating cryoglobulins, this syndrome is called "mixed cryoglobulinemia syndrome" (MCS). Historically, interferon-based therapies in HCV have been associated with lower rates of viral cure in patients with MCS than in the general HCV-infected population. The advent of direct-acting antiviral therapies have revolutionized the treatment of HCV, dramatically increasing rates of cure. Early studies of first-generation protease inhibitors (telaprevir and boceprevir) in combination with interferon and ribavirin demonstrated HCV cure rates of 67% and complete clinical response rates of vasculitis symptoms in 60% of patients with MCS; however, regimens were poorly tolerated by patients, 22% discontinued treatment early. More recently, all-oral, interferon-free regimens have become available and combination therapies are now being approved for patients with and without renal impairment. Patients with HCV-MCS achieved sustained virologic response in 297 out of 313 patients (95%) treated with direct-acting antiviral therapy, and 85% had a complete or partial clinical response of MCS symptoms. Current direct-acting antiviral therapies are well tolerated in patients with HCV-MCS and only 1.6% discontinued treatment early. Patients with cryoglobulinemic glomerulonephritis also had an excellent cure rate (94%). The majority improved; 17/52 (33%) experienced full remission and 15/52 (29%) experienced partial remission. There were no reports of worsening kidney function in patients treated with direct-acting antiviral therapies. Less than 5% of patients with HCV-MCS treated with IFN-free direct-acting antiviral therapy required immunosuppression. However, patients with severe vasculitis appear to still require concomitant immunosuppression.

Fibrillary Glomerulonephritis: An Update

Fibrillary glomerulonephritis (FGN) is a rare proliferative form of glomerular disease characterized by randomly oriented fibrillar deposits with a mean diameter of 20 nm. By immunofluorescence (IF), the deposits stain for IgG, C3, and κ and λ light chains, suggesting that the fibrils may be composed of antigen-antibody immune complexes. A recent major advance in our understanding of the pathogenesis of FGN resulted from the discovery that a major component of the fibrils is DNA-J heat-shock protein family member B9 (DNAJB9), and immunohistochemical staining for DNAJB9 now makes it possible to diagnose FGN in the absence of ultrastructural evaluation. FGN has a poor prognosis, treatment options are currently limited, and transplant recurrence is not uncommon.

Segmentation of Glomeruli Within Trichrome Images Using Deep Learning

Introduction

The number of glomeruli and glomerulosclerosis evaluated on kidney biopsy slides constitute standard components of a renal pathology report. Prevailing methods for glomerular assessment remain manual, labor intensive, and nonstandardized. We developed a deep learning framework to accurately identify and segment glomeruli from digitized images of human kidney biopsies.

Methods

Trichrome-stained images (n = 275) from renal biopsies of 171 patients with chronic kidney disease treated at the Boston Medical Center from 2009 to 2012 were analyzed. A sliding window operation was defined to crop each original image to smaller images. Each cropped image was then evaluated by at least 3 experts into 3 categories: (i) no glomerulus, (ii) normal or partially sclerosed (NPS) glomerulus, and (iii) globally sclerosed (GS) glomerulus. This led to identification of 751 unique images representing nonglomerular regions, 611 images with NPS glomeruli, and 134 images with GS glomeruli. A convolutional neural network (CNN) was trained with cropped images as inputs and corresponding labels as output. Using this model, an image processing routine was developed to scan the test images to segment the GS glomeruli.

Results

The CNN model was able to accurately discriminate nonglomerular images from NPS and GS images (performance on test data: Accuracy: 92.67% ± 2.02% and Kappa: 0.8681 ± 0.0392). The segmentation model that was based on the CNN multilabel classifier accurately marked the GS glomeruli on the test data (Matthews correlation coefficient = 0.628).

Conclusion

This work demonstrates the power of deep learning for assessing complex histologic structures from digitized human kidney biopsies.

New developments in the diagnosis of fibrillary glomerulonephritis

Fibrillary glomerulonephritis is a glomerular disease historically defined by glomerular deposition of Congo red-negative, randomly oriented straight fibrils that lack a hollow center and stain with antisera to immunoglobulins. It was initially considered to be an idiopathic disease, but recent studies highlighted association in some cases with autoimmune disease, malignant neoplasm, or hepatitis C viral infection. Prognosis is poor with nearly half of patients progressing to end-stage renal disease within 4 years. There is currently no effective therapy, aside from kidney transplantation, which is associated with disease recurrence in a third of cases. The diagnosis has been hampered by the lack of biomarkers for the disease and the necessity of electron microscopy for diagnosis, which is not widely available. Recently, through the use of laser microdissection-assisted liquid chromatography-tandem mass spectrometry, a novel biomarker of fibrillary glomerulonephritis, DnaJ homolog subfamily B member 9, has been identified. Immunohistochemical studies confirmed the high sensitivity and specificity of DnaJ homolog subfamily B member 9 for this disease; dual immunofluorescence showed its colocalization with IgG in glomeruli; and immunoelectron microscopy revealed its localization to individual fibrils of fibrillary glomerulonephritis. The identification of this tissue biomarker has already entered clinical practice and undoubtingly will improve the diagnosis of this rare disease, particularly in developing countries where electron microscopy is less available. Future research is needed to determine whether DnaJ homolog subfamily B member 9 is an autoantigen or just an associated protein in fibrillary glomerulonephritis, whether it can serve as a noninvasive biomarker, and whether therapies that target this protein are effective in improving prognosis.

Serum levels of DNAJB9 are elevated in fibrillary glomerulonephritis patients

Fibrillary glomerulonephritis (FGN) is a rare glomerular disease. Kidney biopsy is required to establish the diagnosis. Recent studies have identified abundant glomerular deposition of DNAJB9 as a unique histological marker of FGN. We developed an immunoprecipitation-based multiple reaction monitoring method to measure serum levels of DNAJB9. We detected a 4-fold higher abundance of serum DNAJB9 in FGN patients when compared to controls, including patients with other glomerular diseases. Serum DNAJB9 levels were also negatively associated with estimated glomerular filtration rate in patients with FGN. Serum DNAJB9 levels accurately predicted FGN with moderate sensitivity (67%) and with high specificity (98%) and positive and negative predictive value (89% and 95%, respectively). A receiver operating curve analysis demonstrated an AUC of 0.958. These results suggest that serum levels of DNAJB9 could be a valuable marker to predict FGN, with the potential to complement kidney biopsy for the diagnosis of FGN.

HCV-Associated Nephropathies in the Era of Direct Acting Antiviral Agents

Hepatitis C virus (HCV) infection is a systemic disorder that frequently associates with extrahepatic manifestations, including nephropathies. Cryoglobulinemia is a typical extrahepatic manifestation of HCV infection that often involves kidneys with a histological pattern of membranoproliferative glomerulonephritis. Other, less common renal diseases related to HCV infection include membranous nephropathy, focal segmental glomerulosclerosis, IgA nephropathy, fibrillary and immunotactoid glomerulopathy. Over the last decades, the advent of direct-acting antiviral therapies has revolutionized treatment of HCV infection, dramatically increasing the rates of viral clearance. In patients where antiviral therapy alone fails to induce renal disease remission add-on B-cell depleting agents represent an alternative to counteract the synthesis of pathogenic antibodies. Immunosuppressive therapies, such as steroids, alkylating agents, and plasma exchanges, may still represent an effective option to inhibit immune-complex driven inflammatory response, but the potentially associated increase of HCV replication and worsening of liver disease represent a serious limitation to their use.

Rare diagnosis in a patient with diabetes with nephrotic proteinuria

We report a 63-year-old man with well-controlled type 2 diabetes mellitus and hypertension, who presented with new onset nephrotic proteinuria and rapid deterioration in renal function. The atypical clinical presentation prompted us to consider a non-diabetic and non-hypertensive cause and to perform a renal biopsy. A diagnosis of fibrillarglomerulonephritis (FGn) was made based on electronic microscopy. Proteinuria remained in nephrotic range despite treatment with prednisolone, and renal function deteriorated. We suggest that other causes of proteinuria should be considered in patients with diabetes who present with the nephrotic syndrome when there is no other evidence of microvascular disease. We review the spectrum of fibrillar glomerulopathies including FGn, primary and secondary amyloidosis and immunotactoid glomerulonephritis.

Fibrillary Glomerulonephritis with Crescentic and Necrotizing Glomerulonephritis and Concurrent Thrombotic Microangiopathy

We present a 77-year-old Caucasian woman who presented with nephrotic-range proteinuria, microhematuria, renal impairment, and extremely elevated blood pressure. She had a long history of well-controlled type 2 diabetes. Renal biopsy revealed fibrillary deposits in the mesangium and glomerular basement membrane consistent with fibrillary glomerulopathy (FGN), with crescentic changes and thrombotic microangiopathy (TMA). We could not identify any radiological, clinical, or laboratory evidence of autoimmune disorders, lymphoproliferative disorders, and malignancy. It was decided not to offer her any immunosuppressive therapy, as she was frail with substantial renal damage on the biopsy. Five months after presentation, she gradually progressed to requiring renal replacement therapy and is currently on maintenance hemodialysis. Crescentic changes in FGN, though rare, have been previously described, but the concurrent presence of TMA has never been previously reported.

Autoimmune Kidney Diseases Associated with Chronic Viral Infections

Autoimmune kidney diseases triggered by viruses are an important cause of kidney disease in patients affected by chronic viral infection. Hepatitis B virus (HBV) infection is associated with membranous nephropathy and polyarteritis nodosa. Hepatitis C virus (HCV) infection is a major cause of cryoglobulinemic glomerulonephritis. Patients with human immunodeficiency virus (HIV) may develop HIV-associated nephropathy, a form of collapsing focal segmental glomerulosclerosis, or various forms of immune-complex-mediated kidney diseases. This article summarizes what is known about the pathogenesis, diagnosis, and management of immune-mediated kidney diseases in adults with chronic HBV, HCV, and HIV infections.

Proliferative glomerulonephritis with unusual microlamellar organized deposits related to monoclonal immunoglobulin G3 (IgG3) kappa

A 71-year-old woman presented with massive proteinuria and microhematuria. Renal biopsy showed diffuse global membranoproliferative and endocapillary proliferative lesions with leukocytic infiltration and an irregular duplication of the glomerular basement membrane on light microscopy. Immunofluorescence study showed granular deposits of monoclonal immunoglobulin G3 (IgG3) kappa, C3, and C1q in the glomeruli. Electron microscopy revealed unique structurally organized microlamellar electron-dense deposits. There was no evidence of systemic diseases such as paraproteinemia, cryoglobulinemia, or systemic lupus erythematosus. Following renal biopsy, the oral administration of mizoribine in addition to predonisolone gradually improved the patient's clinical status. So far, partial remission has continued for a year, and she has not been affected with hematopoietic or lymphoproliferative disorders. We report a case of proliferative glomerulonephritis with unusual microlamellar organized deposits related to monoclonal IgG3 kappa. Our case was immunologically identical to proliferative glomerulonephritis with monoclonal IgG deposits (PGNMID). Therefore, we concluded that our case should be categorized as an atypical form of PGNMID, though it was difficult to diagnose using the usual diagnostic approach to glomerular diseases with organized deposits.

Fibrillary Glomerulonephritis in Primary Sjogren's Syndrome: A Rare Cause of Renal Failure

Renal involvement in primary Sjogren's syndrome (pSS) varies in severity and prevalence. Although previously felt to be uncommon, kidneys can be involved in 25% to 30% of pSS patients. Fibrillary glomerulonephritis (FGN) is a rare primary glomerular disease that can occur in association with another autoimmune condition or malignancy. The diagnosis relies on renal biopsy findings of haphazardly arranged fibrils in all glomerular compartments and distinction from other forms of fibrillary glomerulopathies such as renal amyloidosis and immunotactoid glomerulopathy. FGN responds poorly to immunosuppressive therapy and has a poor prognosis. Here, we describe a case of FGN in a patient with asymptomatic pSS. We describe the diagnostic work-up, clinical course, treatment utilized, and 1-year follow-up. There is one other case in the literature of FGN in a patient with pSS. The rarity of this association and distinction of FGN from other forms of renal involvement in pSS is important as it impacts therapy and prognosis. The case highlights electron microscopy findings in FGN and poor prognosis.

DnaJ Homolog Subfamily B Member 9 Is a Putative Autoantigen in Fibrillary GN

Fibrillary GN is a rare form of GN of uncertain pathogenesis that is characterized by the glomerular accumulation of randomly arranged, nonbranching fibrils (12-24 nm) composed of Ig and complement proteins. In this study, we used mass spectrometry to comprehensively define the glomerular proteome in fibrillary GN compared with that in controls and nonfibrillary GN renal diseases. We isolated glomeruli from formalin-fixed and paraffin-embedded biopsy specimens using laser capture microdissection and analyzed them with liquid chromatography and data-dependent tandem mass spectrometry. These studies identified DnaJ homolog subfamily B member 9 (DNAJB9) as a highly sampled protein detected only in fibrillary GN cases. The glomerular proteome of fibrillary GN cases also contained IgG1 as the dominant Ig and proteins of the classic complement pathway. In fibrillary GN specimens only, immunofluorescence and immunohistochemistry with an anti-DNAJB9 antibody showed strong and specific staining of the glomerular tufts in a distribution that mimicked that of the immune deposits. Our results identify DNAJB9 as a putative autoantigen in fibrillary GN and suggest IgG1 and classic complement effector pathways as likely mediators of the destructive glomerular injury in this disease.

DnaJ Heat Shock Protein Family B Member 9 Is a Novel Biomarker for Fibrillary GN

Fibrillary GN (FGN) is a rare primary glomerular disease. Histologic and histochemical features of FGN overlap with those of other glomerular diseases, and no unique histologic biomarkers for diagnosing FGN have been identified. We analyzed the proteomic content of glomeruli in patient biopsy specimens and detected DnaJ heat shock protein family (Hsp40) member B9 (DNAJB9) as the fourth most abundant protein in FGN glomeruli. Compared with amyloidosis glomeruli, FGN glomeruli exhibited a >6-fold overexpression of DNAJB9 protein. Sanger sequencing and protein sequence coverage maps showed that the DNAJB9 protein deposited in FGN glomeruli did not have any major sequence or structural alterations. Notably, we detected DNAJB9 in all patients with FGN but not in healthy glomeruli or in 19 types of non-FGN glomerular diseases. We also observed the codeposition of DNAJB9 and Ig-γ Overall, these findings indicate that DNAJB9 is an FGN marker with 100% sensitivity and 100% specificity. The magnitude and specificity of DNAJB9 overabundance in FGN also suggests that this protein has a role in FGN pathogenesis. With this evidence, we propose that DNAJB9 is a strong biomarker for rapid diagnosis of FGN in renal biopsy specimens.

Histologic regression of fibrillary glomerulonephritis: the first report of biopsy-proven spontaneous resolution of disease

Fibrillary glomerulonephritis (FGN) is a rare immune complex type glomerulonephritis characterized by glomerular deposition of randomly oriented fibrils measuring 10–30 nm in thickness, and typically presents with proteinuria with or without renal insufficiency and hematuria. We present a case in which a patient initially presented at age 41 years with nephrotic-range proteinuria and hypertension; a kidney biopsy showed FGN. The patient was treated with angiotensin receptor blockage only, without immunosuppression as per patient preference, and the level of protein in the urine improved. During the follow-up period of 17 years, the patient developed type 2 diabetes mellitus. The patient re-presented with nephrotic-range proteinuria 17 years later, at the age of 58 years. A kidney biopsy was performed and showed diffuse diabetic glomerulosclerosis with secondary focal segmental glomerulosclerosis and related vascular changes. There was no evidence of FGN by immunofluorescence or electron microscopy. Although FGN has been rarely reported to regress clinically, this is the first documented case of histologic regression of FGN. The potential for FGN fibrils to regress spontaneously is important in the management of FGN patients considering that currently available immunosuppressive agents have limited efficacy, and is an encouraging finding for future studies aiming to find a cure for the disease.

A Case of Fibrillary Glomerulonephritis with Fibril Deposition in the Arteriolar Wall and a Family History of Renal Disease

Herein, we report a case of fibrillary glomerulonephritis (FGN). FGN usually shows non-amyloidal fibrils in the mesangium and glomerular capillary walls on electron microscopy. Inherited cases of FGN have been reported in only 3 families, and the suspected genetic form was autosomal dominant. In the present case, the deposition of microfibrils in the arteriolar wall as well as the glomerulus is unique. Our patient's father died of nephrotic syndrome, and his elder brother had a biopsy-proven glomerulopathy. The histological findings of the brothers are similar to mesangial proliferative glomerulonephritis and resemble each other. Therefore, our case is presumed to be familial FGN. Additionally, herein, we review the literature and reconsider the histological and clinical characters of FGN.

Clinical Features and Outcomes of a Racially Diverse Population with Fibrillary Glomerulonephritis

BACKGROUND

Fibrillary glomerulonephritis is characterized by randomly arranged fibrils, approximately 20 nm in diameter by electron microscopy. Patients present with proteinuria, hematuria and kidney insufficiency, and about half of the reported patients progress to end-stage kidney disease within 4 years. The dependence of patient characteristics and outcomes on race has not been explored. In this study, we describe a cohort of patients with fibrillary glomerulonephritis and compare their clinical characteristics and outcomes with those of patients previously described.

METHODS

The University of North Carolina (UNC) Nephropathology Database was used to retrospectively identify patients diagnosed with fibrillary glomerulonephritis between 1985 and 2015. Of these patients, those treated at UNC were selected. Their demographic and clinical characteristics - including signs and symptoms, comorbidities, laboratory values, treatments and outcomes - were compared with those of patients described earlier.

RESULTS

Among the 287 patients identified, 42 were treated at the UNC Kidney Center. When compared to earlier cohorts, a higher frequency of black race, hepatitis C virus (HCV) infection and use of hemodialysis were noted in both black and HCV-positive patients. Autoimmune diseases, infections and malignancies were frequently observed, present in over half of all cases.

CONCLUSION

According to this study, fibrillary glomerulonephritis represents a secondary glomerular disease process (associated with autoimmune disease, infection or malignancy) in many cases and hence screening is essential. As the screening for comorbidities increased over time, more underlying causes were identified. We noted a high frequency of HCV among black patients, suggesting a possible causative association. Treatment of underlying disease is essential for patients for the best outcome.

Paraneoplastic fibrillary glomerulonephritis associated with intrahepatic cholangiocarcinoma: When diagnosis of a rare kidney disease leads to successful hepatic cancer treatment

A 50-year-old man presented with nephrotic syndrome. Electron microscopy analysis of a kidney biopsy specimen showed fibrillary glomerulonephritis, a rare glomerular disease, while histological analysis of a liver tumor biopsy confirmed an intrahepatic cholangiocarcinoma. The paraneoplastic nature of fibrillary glomerulonephritis is debated but after curative treatment of the hepatic nodule, remission of nephrotic syndrome was confirmed at 6-, 12- and 24-months follow-up. To our knowledge, this is the first description of a paraneoplastic fibrillary glomerulonephritis associated with a cholangiocarcinoma, supported by complete remission achieved following cancer treatment.

Fibrillary glomerulonephritis presenting as crescentic glomerulonephritis

Fibrillary glomerulonephritis (FGN) is a rare primary glomerular disease that commonly presents clinically with hypertension, proteinuria, microscopic hematuria, and varying degree of renal insufficiency. Histologically, FGN can present with different patterns of glomerular injury, more commonly mesangioproliferative, membranoproliferative, and membranous nephropathy. While crescent formation has been described in some kidney biopsy series of FGN, crescentic glomerulonephritis pattern of glomerular injury has been rarely described. Optimal therapy and outcomes in FGN presenting with crescentic GN is not currently known. We report an adult patient who presented with massive proteinuria and severe renal failure. The kidney biopsy revealed crescentic FGN (C-FGN). The patient remained dialysis dependent despite immunosuppressive therapy. We also briefly review FGN, and the few reported cases of C-FGN that presented as rapidly progressive or advanced renal failure in the literature.

Paraprotein-Related Kidney Disease: Glomerular Diseases Associated with Paraproteinemias

Paraproteins are monoclonal Igs that accumulate in blood as a result of abnormal excess production. These circulating proteins cause a diversity of kidney disorders that are increasingly being comanaged by nephrologists. In this review, we discuss paraprotein-related diseases that affect the glomerulus. We provide a broad overview of diseases characterized by nonorganized deposits, such as monoclonal Ig deposition disease (MIDD), proliferative GN with monoclonal Ig deposits (PGNMID), and C3 glomerulopathy, as well as those characterized by organized deposits, such as amyloidosis, immunotactoid glomerulopathy, fibrillary GN, and cryoglobulinemic GN, and rarer disorders, such as monoclonal crystalline glomerulopathies, paraprotein-related thrombotic microangiopathies, and membranous-like glomerulopathy with masked IgGκ deposits. This review will provide the nephrologist with an up to date understanding of these entities and highlight the areas of deficit in evidence and future lines of research.

IgG Subclass Staining in Routine Renal Biopsy Material

Immunofluorescence staining plays a vital role in nephropathology, but the panel of antibodies used has not changed for decades. Further classification of immunoglobulin (Ig)G-containing immune-type deposits with IgG subclass staining (IgG1, IgG2, IgG3, and IgG4) has been shown to be of diagnostic utility in glomerular diseases, but their value in the evaluation of renal biopsies has not been addressed systematically in large renal biopsy material. Between January 2007 and June 2014, using direct immunofluorescence, we stained every renal biopsy for the IgG subclasses if there was moderate to prominent glomerular IgG staining and/or IgG-predominant or IgG-codominant glomerular staining. The total number of biopsies stained was 1084, which included 367 cases of membranous glomerulonephritis, 307 cases of lupus nephritis, 74 cases of fibrillary glomerulonephritis, 53 cases of proliferative glomerulonephritis with monoclonal IgG deposits, and 25 cases of antiglomerular basement membrane disease, among others. We found that monoclonality of IgG deposits cannot always be reliably determined on the basis of kappa and lambda light chain staining alone, particularly if concomitant (frequently nonspecific) IgM staining is present. In IgG heavy and heavy and light chain deposition disease (3 cases), subclass staining is very helpful, and in proliferative glomerulonephritis with monoclonal IgG deposits subclass staining is necessary. IgG subclass staining is useful in differentiating primary from secondary membranous glomerulonephritis. In proliferative glomerulonephritis with polyclonal IgG deposition, IgG1 dominance/codominance with concomitant IgG3 and IgG2 but weak or absent IgG4 staining favors an underlying autoimmune disease. IgG subclass staining is a very useful diagnostic method in a selected cohort of renal biopsies, particularly in biopsies with glomerulonephritis with monoclonal IgG deposits.

Immunotactoid Glomerulopathy and Cryoglobulinemic Nephropathy: Two Entities with Many Similarities. A Unified Conceptual Approach

Immunotactoid glomerulopathy is a rare disorder that has been characterized at the ultrastructural level. Due to its rarity, there are few comprehensive studies relating to this disorder. Electron microscopy essentially characterizes this disease. The glomerular electron dense deposits which are typical of this condition consist of aggregates of highly organized microtubular structures of various diameters, but generally measuring 30-50 nm in width with a propensity to dispose themselves in parallel bundles intersecting in different planes. This study compares a large series of patients with cryoglobulinemic nephropathy with a series of patients with immunotactoid glomerulopathy to address whether there may be similarities that warrant considering these two entities part of a spectrum. This study reviews the clinicopathologic features of both entities and emphasizes ultrastructural findings that characterize them. Significant immunomorphologic overlap was found when these two disorders were compared in this study. There were also striking similarities in clinical presentation/behavior, laboratory findings and prognosis. Proteomic analysis has also demonstrated similar spectra for both entities. We postulate that immunotactoid glomerulopathy and cryoglobulinemic nephropathy are part of the spectrum of renal manifestations in patients with circulating cryoglobulins and renal disease.