Membranoproliferative glomerulonephritis in a child with congenital portosystemic shunt.

Congenital portosystemic shunts (CPSS) are rare congenital vascular anomalies characterized by abnormal connections between the portal vein and systemic circulation, bypassing the liver. They can lead to complications such as recurrent encephalopathy, liver nodules, portopulmonary hypertension, and neurocognitive issues due to hyperammonemia and rarely kidney involvement. Hepatic hemodynamic changes can lead to liver nodules and hepatocellular carcinoma, particularly in extrahepatic shunts. We describe here an 11-year-old girl with type 1 intrahepatic portosystemic shunt with focal nodular hyperplasia in the liver, presenting with nephrotic syndrome that was diagnosed as membranoproliferative glomerulonephritis on kidney biopsy and that responded partially to therapy with immunosuppressants.

Pathological evaluation of renal complications in children following allogeneic hematopoietic stem cell transplantation: a retrospective cohort study.

BACKGROUND: Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a curative therapy for hematologic malignancies and non-malignant disorders, such as aplastic anemia, fanconi anemia, and certain immune deficiencies. Post-transplantation kidney injury is a common complication and involves a wide spectrum of structural abnormalities, including glomerular (MSPGN, mesangial proliferative glomerulonephritis; FSGS, focal segmental glomerulosclerosis; MPGN, membranoproliferative glomerulonephritis; MCD, minimal change disease), vascular (TMA, thrombotic microangiopathy), and/or tubulointerstitial (TIN, tubulointerstitial nephritis; ATI, acute tubular injury). Renal biopsy is the gold-standard examination for defining multiple etiologies of kidney impairment. Although kidney injury following HSCT has been studied, little is known about the effects of allo-HSCT on renal pathology in pediatric patients. METHODS: We retrospectively analyzed renal biopsy specimens from children with kidney injury after allo-HSCT and correlated results with clinical data in the last 10 years. RESULTS: Among 25 children (18 males and 7 females), three patients had proteinuria indicating nephrotic syndrome (24-hour urinary total protein/weight > 50 mg/kg/d), nine patients had severely reduced estimated glomerular filtration rate (eGFR < 30 ml/min/1.73 m2) and four patients received kidney replacement therapy (KRT). The main pathologies identified from kidney biopsies were MSPGN (n = 12), FSGS (n = 12), MPGN (n = 5), TMA (n = 4), MCD (n = 3), diffuse glomerular fibrosis (DGF, n = 2), ATI and TIN, in isolation or combined with other pathologies. The median follow-up time was 16.5 (0.5 ~ 68.0) months. Three patients died of recurrent malignancy and/or severe infection, one child developed to end-stage renal disease (ESRD), six patients (24%) had elevated serum creatinine (SCr > 100µmol/l) and nine patients (36%) still had proteinuria. CONCLUSIONS: This study evaluates histomorphologic findings from kidney biopsies of pediatric recipients following allo-HSCT. Detailed evaluation of renal biopsy samples is helpful to elucidate the nature of renal insult, and may potentially identify treatable disease processes.

WT1 complete gonadal dysgenesis with membranoproliferative glomerulonephritis: case series and literature review.

BACKGROUND: Intronic WT1 mutations are usually causative of Frasier syndrome with focal segmental glomerulosclerosis as the characteristic nephropathy. Membranoproliferative glomerulonephritis is not commonly associated with disorders of sex development but has been recently identified as a WT1-associated nephropathy, but usually in cases of exonic mutations in either isolated Wilms tumor or Denys-Drash syndrome. METHODS: The clinical and genetic data from 3 individuals are reported. RESULTS: This report describes the kidney manifestations in 3 individuals from 2 unrelated families with Frasier syndrome intronic WT1 mutations, noting that 2 of the 3 individuals have histologically confirmed membranoproliferative glomerulonephritis. CONCLUSIONS: These case reports support expansion of the clinical spectrum of the kidney phenotypes associated with Frasier syndrome providing evidence of an association between WT1 mutation and an immune complex-related membranoproliferative glomerulonephritis. A higher resolution version of the Graphical abstract is available as Supplementary information.

Proliferative Glomerulonephritis With Fibrils, Monoclonal κ Light Chain, and C3 Deposits.

There is increasing recognition of monoclonal gammopathy as a cause of proliferative glomerulonephritis (GN), including cases in which glomerular deposition of monoclonal immunoglobulin is demonstrated. Recently, proliferative GN with monoclonal immunoglobulin deposits (PGNMID) has incorporated a light chain variant of the disease (termed PGNMID-LC). Intriguingly, glomerular co-deposition of C3 is found in addition to monotypic light chain, implying complement activation via the alternative pathway (AP). We present a unique case of proliferative GN in a 42-year-old man who presented with nephrotic syndrome and was found to have κ light chain multiple myeloma. Immune staining of the glomerulus was positive only for κ light chain and C3, with the striking appearance of nonamyloid fibrils on electron microscopy. Following clonally targeted therapy for myeloma, the renal clinical abnormalities resolved completely. We present detailed molecular studies for light chain and complement and consider local mechanisms whereby monoclonal κ light chain fibrils may have triggered AP activation within the glomerulus.

Large-Scale Whole-Genome Sequencing Reveals the Genetic Architecture of Primary Membranoproliferative GN and C3 Glomerulopathy.

BACKGROUND: Primary membranoproliferative GN, including complement 3 (C3) glomerulopathy, is a rare, untreatable kidney disease characterized by glomerular complement deposition. Complement gene mutations can cause familial C3 glomerulopathy, and studies have reported rare variants in complement genes in nonfamilial primary membranoproliferative GN. METHODS: We analyzed whole-genome sequence data from 165 primary membranoproliferative GN cases and 10,250 individuals without the condition (controls) as part of the National Institutes of Health Research BioResource-Rare Diseases Study. We examined copy number, rare, and common variants. RESULTS: Our analysis included 146 primary membranoproliferative GN cases and 6442 controls who were unrelated and of European ancestry. We observed no significant enrichment of rare variants in candidate genes (genes encoding components of the complement alternative pathway and other genes associated with the related disease atypical hemolytic uremic syndrome; 6.8% in cases versus 5.9% in controls) or exome-wide. However, a significant common variant locus was identified at 6p21.32 (rs35406322) (P=3.29×10-8; odds ratio [OR], 1.93; 95% confidence interval [95% CI], 1.53 to 2.44), overlapping the HLA locus. Imputation of HLA types mapped this signal to a haplotype incorporating DQA1*05:01, DQB1*02:01, and DRB1*03:01 (P=1.21×10-8; OR, 2.19; 95% CI, 1.66 to 2.89). This finding was replicated by analysis of HLA serotypes in 338 individuals with membranoproliferative GN and 15,614 individuals with nonimmune renal failure. CONCLUSIONS: We found that HLA type, but not rare complement gene variation, is associated with primary membranoproliferative GN. These findings challenge the paradigm of complement gene mutations typically causing primary membranoproliferative GN and implicate an underlying autoimmune mechanism in most cases.

Focal Segmental Membranoproliferative Glomerulonephritis: A Histological Variant of Denys-Drash Syndrome.

Introduction: Denys-Drash Syndrome (DDS) consists of a triad of pseudohermaphroditism, Wilms'tumor and nephropathy. This condition may manifest as a complete triad or in an incomplete form; with either one or a combination of the above features. The characteristic glomerular abnormality in DDS is diffuse mesangial sclerosis (DMS).Case report: We report two cases of DDS with focal membranoproliferative glomerulonephritis (MPGN). Both of our cases were males with ambiguous genitalia. They had a similar heterozygous germline mutation in exon 9 of WT1, c.1180C>T, p.R394W; a known mutation hotspot for DDS. Case 1 had nephropathy at the age of 4 years and Case 2 at 2.5 years with different rates of progression to end-stage renal failure. Conclusion: Our findings, in combination with other reports, illustrate the clinicopathological heterogeneity of DDS. There are no universal recommendations for optimal management of patients with DDS due to the inability to accurately predict affected individuals' progress.

TAFRO syndrome as a cause of glomerular microangiopathy: a case report and literature review.

BACKGROUND: TAFRO syndrome is a systemic inflammatory disorder that manifests as thrombocytopenia (T), anasarca (A), fever (F), reticulin fibrosis (R), and organomegaly (O). Renal dysfunction is frequently complicated with TAFRO syndrome, however, it is challenging to perform kidney biopsy in patients with TAFRO syndrome in the presence of thrombocytopenia. Renal histology in TAFRO syndrome mainly shows membranoproliferative glomerulonephritis (MPGN)-like lesions or thrombotic microangiopathy (TMA)-like glomerulopathy. We review our case and previous reports of TAFRO syndrome with kidney biopsy findings and discuss the renal pathophysiology of TAFRO syndrome. CASE PRESENTATION: We describe a previously healthy 48- year-old woman with TAFRO syndrome. Kidney biopsy performed before the treatment showed diffuse global endocapillary proliferative changes with endothelial cell swelling, double contours of partial capillary walls, and mesangiolysis, consistent with TMA-like glomerulopathy. Glucocorticoid therapy including steroid pulse was ineffective and she developed anasarca, renal dysfunction and oliguria. Hemodialysis was required. However, the anti-Interleukin (IL)-6 receptor antibody (tocilizumab) therapy was very effective. An increase in urinary volume was achieved about 2 weeks after the tocilizumab therapy and hemodialysis was discontinued. To investigate the renal pathophysiology of TAFRO syndrome, we performed immunohistological staining of vascular endothelial growth factor (VEGF)-A, CD34, and D2-40, in our case and a normal control kidney. Glomerular VEGF-A was especially positive in podocytes both, in the control and in the case, with no significant difference and there was a significant increase of VEGF-A staining area in the cortical peritubular capillaries in the case. Both glomerular and renal cortical CD34 expression were significantly decreased in our case. D2-40 expression in cortex was not significantly different. CONCLUSIONS: We reviewed our case and other 10 previous reports about renal biopsy findings in TAFRO syndrome and found that glomerular microangiopathy was a common finding. IL-6-VEGF-axis-induced glomerular microangiopathy may play a crucial role in developing acute kidney injury in TAFRO syndrome and the anti-IL-6 receptor antibody therapy may be useful for TAFRO syndrome refractory to glucocorticoids. About the pathophysiology of VEGF in TAFRO syndrome, VEGF balance in the glomerulus and perhaps in the peritubular capillary system as well may be critical. Further investigation is needed.

Prevention of Fatal C3 Glomerulopathy by Recombinant Complement Receptor of the Ig Superfamily.

Background C3 glomerulopathy (C3G) is a life-threatening kidney disease caused by dysregulation of the alternative pathway of complement (AP) activation. No approved specific therapy is available for C3G, although an anti-C5 mAb has been used off-label in some patients with C3G, with mixed results. Thus, there is an unmet medical need to develop other inhibitors of complement for C3G.Methods We used a murine model of lethal C3G to test the potential efficacy of an Fc fusion protein of complement receptor of the Ig superfamily (CRIg-Fc) in the treatment of C3G. CRIg-Fc binds C3b and inhibits C3 and C5 convertases of the AP. Mice with mutations in the factor H and properdin genes (FHm/mP-/-) develop early-onset C3G, with AP consumption, high proteinuria, and lethal crescentic GN.Results Treatment of FHm/mP-/- mice with CRIg-Fc, but not a control IgG, inhibited AP activation and diminished the consumption of plasma C3, factor B, and C5. CRIg-Fc-treated FHm/mP-/- mice also had significantly improved survival and reduced proteinuria, hematuria, BUN, glomerular C3 fragment, C9 and fibrin deposition, and GN pathology scores.Conclusions Therapeutics developed on the basis of the mechanism of action of soluble CRIg may be effective for the treatment of C3G and should be explored clinically.

An Engineered Complement Factor H Construct for Treatment of C3 Glomerulopathy.

Background C3 glomerulopathy (C3G) is associated with dysregulation of the alternative pathway of complement activation, and treatment options for C3G remain limited. Complement factor H (FH) is a potent regulator of the alternative pathway and might offer a solution, but the mass and complexity of FH makes generation of full-length FH far from trivial. We previously generated a mini-FH construct, with FH short consensus repeats 1-5 linked to repeats 18-20 (FH1-5^18-20), that was effective in experimental C3G. However, the serum t1/2 of FH1-5^18-20 was significantly shorter than that of serum-purified FH.Methods We introduced the oligomerization domain of human FH-related protein 1 (denoted by R1-2) at the carboxy or amino terminus of human FH1-5^18-20 to generate two homodimeric mini-FH constructs (FHR1-2^1-5^18-20 and FH1-5^18-20^R1-2, respectively) in Chinese hamster ovary cells and tested these constructs using binding, fluid-phase, and erythrocyte lysis assays, followed by experiments in FH-deficient Cfh-/- mice.Results FHR1-2^1-5^18-20 and FH1-5^18-20^R1-2 homodimerized in solution and displayed avid binding profiles on clustered C3b surfaces, particularly FHR1-2^1-5^18-20 Each construct was >10-fold more effective than FH at inhibiting cell surface complement activity in vitro and restricted glomerular basement membrane C3 deposition in vivo significantly better than FH or FH1-5^18-20 FH1-5^18-20^R1-2 had a C3 breakdown fragment binding profile similar to that of FH, a >5-fold increase in serum t1/2 compared with that of FH1-5^18-20, and significantly better retention in the kidney than FH or FH1-5^18-20Conclusions FH1-5^18-20^R1-2 may have utility as a treatment option for C3G or other complement-mediated diseases.

Cluster Analysis Identifies Distinct Pathogenetic Patterns in C3 Glomerulopathies/Immune Complex-Mediated Membranoproliferative GN.

Membranoproliferative GN (MPGN) was recently reclassified as alternative pathway complement-mediated C3 glomerulopathy (C3G) and immune complex-mediated membranoproliferative GN (IC-MPGN). However, genetic and acquired alternative pathway abnormalities are also observed in IC-MPGN. Here, we explored the presence of distinct disease entities characterized by specific pathophysiologic mechanisms. We performed unsupervised hierarchical clustering, a data-driven statistical approach, on histologic, genetic, and clinical data and data regarding serum/plasma complement parameters from 173 patients with C3G/IC-MPGN. This approach divided patients into four clusters, indicating the existence of four different pathogenetic patterns. Specifically, this analysis separated patients with fluid-phase complement activation (clusters 1-3) who had low serum C3 levels and a high prevalence of genetic and acquired alternative pathway abnormalities from patients with solid-phase complement activation (cluster 4) who had normal or mildly altered serum C3, late disease onset, and poor renal survival. In patients with fluid-phase complement activation, those in clusters 1 and 2 had massive activation of the alternative pathway, including activation of the terminal pathway, and the highest prevalence of subendothelial deposits, but those in cluster 2 had additional activation of the classic pathway and the highest prevalence of nephrotic syndrome at disease onset. Patients in cluster 3 had prevalent activation of C3 convertase and highly electron-dense intramembranous deposits. In addition, we provide a simple algorithm to assign patients with C3G/IC-MPGN to specific clusters. These distinct clusters may facilitate clarification of disease etiology, improve risk assessment for ESRD, and pave the way for personalized treatment.

Cryoglobulinemic Glomerulonephritis Associated With Nodal and Renal Infiltration by T-Cell Lymphoma of T-Follicular Helper Phenotype: A Case Report.

We present a unique case of cryoglobulinemic glomerulonephritis associated with nodal and renal infiltration by T-cell lymphoma of T-follicular helper phenotype. The patient presented with transient neurologic symptoms, severe nephritic syndrome with nephrotic-range proteinuria, and acute kidney injury. He had elevated double-stranded DNA levels, low complement levels, detectable cryoglobulin, and detectable immunoglobulin M (IgM) paraprotein. The kidney biopsy showed cryoglobulinemic glomerulonephritis with a membranoproliferative pattern and diffuse interstitial infiltrates on light microscopy; IgM, C3 but weak IgG, C1q, and negative C4d staining on immunofluorescence; and deposits with organized substructures on electron microscopy. Positron emission tomography showed diffuse uptake in bilaterally enlarged kidneys and a localized group of lymph nodes. Subsequent lymph node biopsy revealed Epstein-Barr virus-negative nodal T-cell lymphoma, which was also proven in renal tissue. The association between T-cell lymphoma, autoantibodies, and cryoglobulinemia may represent a paraneoplastic phenomenon. His renal prognosis has been excellent, but overall prognosis and survival is dictated by the clinical course of T-cell lymphoma.

Patterns of Clinical Response to Eculizumab in Patients With C3 Glomerulopathy.

BACKGROUND: Cases reports and small series of patients with C3 glomerulopathy have reported variable efficacy of eculizumab. STUDY DESIGN: Case series of C3 glomerulopathy. SETTING & PARTICIPANTS: Pediatric and adult patients with C3 glomerulopathy treated with eculizumab between 2010 and 2016 were identified through the C3 glomerulopathy French registry database, and a questionnaire was sent to participating French pediatric and adult nephrology centers, as well as one pediatric referral center in Québec, Canada. OUTCOMES: Global or partial clinical renal response. MEASUREMENTS: Evolution of serum creatinine and proteinuria values. RESULTS: 26 patients (13 children/adolescents) were included. 22 (85%) patients had received steroids, plasma exchange, or immunosuppressive therapy before eculizumab, and 3 of them had rapid progression of their kidney disease despite treatment. At the initiation of eculizumab therapy, 11 (42%) patients had chronic kidney disease, 7 (27%) had rapidly progressive disease, and 3 (12%) required dialysis. After eculizumab treatment (median duration, 14 months), 6 (23%) patients had a global clinical response; 6 (23%), a partial clinical response; and 14 (54%), no response. Compared with those who had a partial clinical or no response, patients who had a global clinical response had lower estimated glomerular filtration rates, a more rapidly progressive course, and more extracapillary proliferation on kidney biopsy. Age, extent of renal fibrosis, frequency of nephrotic syndrome, low serum C3 and C3 nephritic factor and elevated soluble C5b-9 concentrations, or complement gene variants did not differ between responders and nonresponders. LIMITATIONS: Retrospective design without a control group, relatively small number of cases, inclusion of pediatric and adult cases. CONCLUSIONS: Eculizumab appears to be a potential treatment for patients with crescentic rapidly progressive C3 glomerulopathy. Its benefit in patients with non-rapidly progressing forms seems to be limited.

Development of membranoproliferative glomerulonephritis-like glomerulopathy in a patient with neutrophilia resulting from endogenous granulocyte-colony stimulating factor overproduction: a case report.

BACKGROUND: The pathophysiologic role of exogenous granulocyte-colony stimulating factor (G-CSF) administration is reportedly linked to the progression of glomerulonephritis. However, the relationship between endogenous G-CSF overproduction and the progression of glomerulopathy has not been well investigated. CASE PRESENTATION: A 76-year-old woman presented with neutrophilia at a medical check-up and thorough examination revealed a high level of serum G-CSF. She subsequently developed mild renal dysfunction and proteinuria. Her renal biopsy showed lobulation of the glomeruli with mesangial proliferation and glomerular capillary walls with a double contour but no immune complex deposition, suggesting membranoproliferative glomerulonephritis-like glomerulopathy. Thereafter, her proteinuria levels fluctuated in parallel with the changes in her blood neutrophil count and finally reduced considerably in association with her decreased neutrophil count. CONCLUSIONS: The unique features of this case suggest that endogenous overproduction of G-CSF could play an important role in the pathogenesis of active glomerulonephritis.

Long-term graft outcomes and patient survival are lower posttransplant in patients with a primary renal diagnosis of glomerulonephritis.

Glomerulonephritis (GN) is the primary diagnosis in 20% to 40% of patients receiving a renal transplant. Here we studied patient survival and graft outcomes in patients with GN transplanted in the UK. UK Renal Registry data were used to analyze patient survival and graft failure in incident transplant patients between 1997 to 2009 who had a diagnosis of primary GN, in comparison to patients transplanted with adult polycystic kidney disease (APKD) or diabetes. Multivariable regression analysis adjusted for age, sex, donor type, ethnicity, donor age, time on dialysis, human leukocyte antigen mismatch, cold ischemic time, and graft failure (for patient survival). Patients were followed up through December 2012. Of 4750 patients analyzed, 2975 had GN and 1775 APKD. Graft failure was significantly higher in membranoproliferative glomerulonephritis (MPGN) type II (hazard ratio: 3.5, confidence interval: 1.9-6.6), focal segmental glomerulosclerosis (2.4, 1.8-3.2), MPGN type I (2.3, 1.6-3.3), membranous nephropathy (2.0, 1.4-2.9), and IgA nephropathy (1.6, 1.3-2.0) compared to APKD. Survival was significantly reduced in patients with MPGN type II (4.7, 2.0-10.8), and those with lupus nephritis (1.8, 1.1-2.9). Overall graft failure for patients with GN was similar to those with diabetes. Thus, in comparison to outcomes in APKD, graft survival is significantly lower in most GNs, with variation in outcomes between different GNs. This information should assist in pretransplant counseling of patients. Further study is required to understand the reduced survival seen in lupus nephritis and MPGN type II, and to improve overall graft outcomes.

C4 Glomerulopathy: A Disease Entity Associated With C4d Deposition.

Complement-mediated glomerulonephritis, which includes C3 glomerulopathy, is characterized by dominant staining of C3 with minimal or no immunoglobulin deposits on immunofluorescence studies. We describe a new entity of complement-mediated glomerulonephritis that is characterized by bright C4d staining but with no or minimal C3 or immunoglobulin deposits on immunofluorescence studies. We label this entity as C4 glomerulopathy. C4 glomerulopathy includes C4 dense deposit disease and C4 glomerulonephritis. C4 dense deposit disease is characterized by bright C4d staining and dense deposits along glomerular basement membranes. C4 glomerulonephritis is characterized by bright C4d staining and many mesangial electron-dense deposits, with or without rare intramembranous electron-dense deposits. We describe clinical features and kidney biopsy results in a short series of 3 patients to highlight these findings. All 3 patients presented with proteinuria, and 2 patients also had hematuria. Kidney function was preserved in 2 patients, whereas 1 patient presented with declining kidney function. Evaluation for autoimmune disease, infection, and paraprotein yielded negative results in all patients. Complement levels were normal, although 1 patient had borderline low C4 levels. Kidney biopsy showed mesangial proliferative or membranoproliferative glomerulonephritis with bright C4d staining and absent or minimal C1q, C3, and immunoglobulin. Laser microdissection and mass spectrometry of glomeruli in all 3 patients showed large to moderate numbers of spectra matching C4. Furthermore, analysis of amino acid sequences showed that they were localized to the C4d portion of C4, consistent with immunofluorescence findings. Further studies are required to determine the underlying cause. In summary, we describe a novel complement-mediated glomerulonephritis that is characterized by bright glomerular C4d staining with minimal or absent staining for C1q, C3, and immunoglobulin.

C4d as a Diagnostic Tool in Proliferative GN.

Proliferative GN is classified as immune complex-mediated or complement-mediated (C3 glomerulopathy). Immune complex-mediated GN results from glomerular deposition of immune-complexes/Ig and C3; the C3 is derived from activation of the classical and/or lectin pathways of complement. C3 glomerulopathy results from deposition of C3 and other complement fragments with minimal or no deposition of immune complexes/Ig; the C3 is derived from activation of the alternative pathway of complement. C4d is a byproduct of activation of the classic and lectin pathways. Although widely used as a marker for antibody-mediated rejection, the significance of C4d in C3 glomerulopathy is undetermined. We studied glomerular C4d staining in 18 biopsy specimens of immune-complex GN, 30 biopsy specimens of C3 GN, and 13 biopsy specimens of postinfectious GN. All specimens of immune complex-mediated GN, except two specimens of IgA nephropathy and one specimen of sclerosing membranoproliferative GN, showed bright (2-3+) C4d staining. The staining pattern of C4d mirrored the staining patterns of Ig and C3. Conversely, C4d staining was completely negative in 24 (80%) of 30 specimens of C3 glomerulopathy, and only trace/1+ C4d staining was detected in six (20%) specimens. With regard to postinfectious GN, C4d staining was negative in six (46%) of 13 specimens, suggesting an abnormality in the alternative pathway, and it was positive in seven (54%) specimens. To summarize, C4d serves as a positive marker for immune complex-mediated GN but is absent or minimally detected in C3 glomerulopathy.

An Aggressive Case of Cryoglobulinemia and Membranoproliferative Glomerulonephritis: A Case Report.

This case report describes a 66-year-old female with membranoproliferative glomerulonephritis (MPGN) with pulmonary involvement presumed secondary to Hepatitis C virus (HCV)-associated with mixed cryoglobulinemia. In this condition, pulmonary involvement is uncommon, and aggressive lung involvement can be associated with poor outcomes. Within eight weeks, the patient was hospitalized twice with acute pulmonary presentations and presented at a third hospitalization with dyspnea, chest pain, abdominal pain, and edema. Imaging revealed persistent and historically evolving lung consolidation, as well as a renal biopsy showing MPGN associated with mixed cryoglobulinemia. A lung biopsy revealed inflammation. Bronchoalveolar lavage did not show hemosiderin-laden macrophages and did not grow infectious agents. Serology revealed negative ANCAs and rheumatoid factor positive at 476 IU/ml (upper limit normal 14 IU/ml). Qualitative cryoglobulins were positive at 2 %ppt (reference range: negative %ppt) and Type II mixed cryoglobulinemia with IgM kappa plus polyclonal IgG. The treatment involved steroids and rituximab. The patient's clinical status deteriorated, and she elected to change her resuscitation status to comfort care measures. This case emphasizes that cryoglobulinemia can present with aggressive manifestations on a wide spectrum. Pulmonary manifestations are rare and were evident in this case (although without clear evidence of diffuse alveolar hemorrhage) and led to a complicated disease course and an unfavorable outcome. Overall, this case underscores the complexity of mixed cryoglobulinemia presentations and the challenges of managing severe cases with multi-organ involvement.

C3 glomerulonephritis associated with monoclonal gammopathy: a case series.

BACKGROUND: C3 glomerulonephritis (GN) is a proliferative GN resulting from glomerular deposition of complement factors due to dysregulation of the alternative pathway of complement. Dysregulation of the alternative pathway of complement may occur as a result of mutations or functional inhibition of complement-regulating proteins. Functional inhibition of the complement-regulating proteins may result from a monoclonal gammopathy. STUDY DESIGN: Case series. SETTING & PARTICIPANTS: 32 Mayo Clinic patients with C3 GN, 10 (31%) of whom had evidence of a monoclonal immunoglobulin in serum. OUTCOMES: Clinical features, hematologic and bone marrow biopsy findings, kidney biopsy findings, kidney measures, complement pathway abnormalities, treatment, and follow-up of patients with C3 GN that was associated with a monoclonal gammopathy. RESULTS: Mean age of patients with C3 GN associated with monoclonal gammopathy was 54.5 years. Bone marrow biopsy done in 9 patients revealed monoclonal gammopathy of undetermined significance in 5 patients, small lymphocytic lymphoma/chronic lymphocytic leukemia in one patient, and no abnormal clones in the other 3 patients. Kidney biopsy showed membranoproliferative GN with bright capillary wall C3 staining in all 10 patients. Evaluation of the alternative pathway of complement showed abnormalities in 7 of 9 patients tested. No mutation in complement-regulating proteins was detected in any patient. As an index case, one patient with C3 GN and chronic lymphocytic leukemia was treated with rituximab, cyclophosphamide, vincristine, and prednisone, and one patient with C3 GN and monoclonal gammopathy of undetermined significance was treated with dexamethasone and bortezomib. Both patients showed significant decreases in hematuria and proteinuria and stabilization of kidney function. LIMITATIONS: Studies to show evidence of direct activation of the alternative pathway by monoclonal immunoglobulin were not done. CONCLUSIONS: The study highlights the association of C3 GN and monoclonal gammopathy, in particular in the older population, and the importance of targeting the underlying hematologic malignancy as an approach to treating C3 GN.

Systemic Haemophilus parainfluenzae Infection Manifesting With Endocarditis and Membranoproliferative Glomerulonephritis.

Infective endocarditis (IE) is a potentially fatal disease that is primarily caused by Staphylococci and Streptococci. The HACEK group of bacteria (Hemophilus species, Aggregatibacter species, Cardiobacterium hominis, Eikenella corrodens, Kingella kingae) account for only 1-3% of reported IE cases. IE has long been known to cause glomerulonephritis. The most common histologic patterns seen are crescentic and diffuse proliferative glomerulonephritis. Notably, membranoproliferative glomerulonephritis (MPGN) is one of the less common patterns seen with IE. We present a rare case of MPGN associated with Haemophilus parainfluenzae endocarditis. A 56-year-old male with no significant past medical history presented to a local hospital with complaints of fever, night sweats, dyspnea, diarrhea, and dark urine for about a month. He was found to have a hemoglobin of 4g/dL, requiring multiple transfusions. He also had bilateral pleural effusions and pulmonary edema. In the following days, he had worsening renal function and was transferred to our hospital for further workup. Initial labs showed anemia, thrombocytopenia, and leukocytosis. He had creatinine elevated at 5.28 mg/dL and a low estimated glomerular filtration rate (eGFR) of 12 mL/min/1.73m2. Urinalysis showed proteinuria, urine hemoglobin, urine white blood cells (WBCs), and red blood cells (RBCs). Blood cultures revealed H. parainfluenzae. Transesophageal echocardiogram (TEE) showed large vegetations with perforation of the mitral valve leaflet. Serology showed low complement levels. Renal biopsy displayed a membranoproliferative pattern of glomerulonephritis on light microscopy. The hepatitis panel was negative, as was the autoimmune workup. The patient was diagnosed with MPGN associated with H. parainfluenzae endocarditis. His complex clinical course required mitral valve replacement and aortic valve repair. He completed the course of antibiotics, with improvement in renal and cardiac function.