Biopsy-proven thrombotic microangiopathy without schistocytosis on peripheral blood smear: A cautionary tale

Efficacy and Safety of Eculizumab in Enteroaggregative E. coli Associated Hemolytic Uremic Syndrome

BACKGROUND

Hemolytic uremic syndrome (HUS) may present atypically without the full triad of classical HUS. Eculizumab has been shown to be efficacious in complement-mediated atypical HUS and some cases of Shiga-toxin (ST) associated HUS. We report the utility of eculizumab in enteroaggregative E. coli (EAEC) associated HUS.

CASE SUMMARY

A female toddler presented with hemolytic anemia, oliguric acute kidney injury (AKI) without thrombocytopenia, and peripheral schistocytes. The stool examination for ST was negative but positive for EAEC. She required several hemodialysis sessions and received one dosage of eculizumab with rapid reversal of AKI and hemolytic markers. A kidney biopsy revealed acute tubular injury and segmental glomerular basement membrane splitting. Genetic testing was negative for complement mutations or deficiencies. A follow-up six months later showed persistently normal renal function and hematological markers.

CONCLUSION

The clinical and histological manifestations of non-ST-associated diarrheal HUS and the role of eculizumab in this condition warrant future larger studies.

Overlap of C3 Glomerulopathy and Thrombotic Microangiopathy: A Case Series

Introduction

Dysregulation of alternative complement pathway underlies the pathogenesis of both C3 glomerulopathy (C3G) and thrombotic microangiopathy (TMA). In this study, we describe both disease entities occurring in 5 patients.

Methods

We identified 114 patients at our institution from 2007 to 2016 with C3G in native kidney biopsies and those with concurrent TMA were included.

Results

The median age at diagnosis was 58 years (range: 28-69); all were male. Median serum creatinine and proteinuria at presentation were 2.3 mg/dl and 2089 mg/d, respectively. Three cases presented with TMA-predominant phenotype and 2 with C3G-predominant phenotype. Immunofluorescence (IF) showed bright C3 staining in mesangium and/or capillary walls. Electron microscopy showed marked subendothelial expansion by fluffy material in the capillary loops without associated deposits. However, capillary wall deposits were present in other loops in 4 cases. Mesangial deposits were present in all cases. Four cases showed low C3, of which 2 showed low C4. Complement evaluation in 3 cases showed pathogenic CFH mutation in 1 case, and multiple variant of unknown significance along with factor B autoantibody and C4 nephritic factor in 1 case. One patient negative for complement abnormalities had a monoclonal gammopathy. Three cases were treated with steroids and/or immunosuppressants. One case progressed to end-stage renal disease (ESRD) at 38.3 months; the remaining showed median serum creatinine and proteinuria of 2.5 mg/dl and 1169 mg/d, respectively at median follow-up of 17.5 months.

Conclusion

Overlap of C3G and TMA is rare and can clinically present as C3G-predominant or TMA-predominant phenotype. The significance of concurrent C3G/TMA findings on long-term renal survival remains to be explored.

Acute GVHD, BK hemorrhagic cystitis and age are risk factors for transplant-associated thrombotic microangiopathy in adults

Clinically actionable thrombotic microangiopathy (CA-TMA) occurring in the absence of aGVHD occurs earlier than day 100.

aGVHD is a key and consistent risk factor for late-onset CA-TMA.

Hematopoietic cell transplantation–associated thrombotic microangiopathy (TMA) is a complication associated with higher nonrelapse mortality (NRM) in patients who undergo allogeneic transplant (HCT). Current classification criteria are not generally agreed on or validated, and the presence of confounding factors after transplant contribute to underdiagnosis or delayed diagnosis of TMA. We studied risk factors, incidence, and biomarkers of TMA in 119 adult allogeneic HCT recipients. Twenty-seven patients developed a clinically actionable phenotype of TMA (CA-TMA) and the incidence of CA-TMA was 22% by day 180. Among the 27 patients who developed CA-TMA, 10 developed it before the onset of acute graft-versus-host disease (aGVHD), and 17 patients developed it after the onset of aGVHD. We report for the first time that age >50 years, BK hemorrhagic cystitis, and other viral infections (CMV, HHV-6, or adenovirus) are risk factors for adult CA-TMA. Even after adjustment for aGVHD, CA-TMA was independently associated with significantly higher NRM. These data illustrate relationships between CA-TMA and aGVHD, describe new risk factors for CA-TMA and emphasizes the need to develop validated set of criteria for timely diagnosis.

High prevalence of CFHR deletions in Indian women with pregnancy-associated hemolytic uremic syndrome

AIM

Pregnancy-associated hemolytic uremic syndrome (P-aHUS) is an important cause of peripartum acute kidney injury. Studies from Europe have described mutations in complement regulator genes, and data in Indian patients is scarce. Hence this study used multiplex ligation-dependent probe amplification (MLPA) to identify variants in complement genes in P-aHUS patients.

METHODS

We present 17 patients of P-aHUS who were investigated for complement protein levels and genetic analysis with MLPA for complement genes. Plasma exchange therapy was offered to all patients presenting in acute phase.

RESULTS

Mean age 26.74 (3.36) years with 15/17 delivered by caesarean section. Eleven patients received early (within 7 days) plasma exchange, three were dialysis-dependent at 3 months and seven were dialysis-free. Only one of the three patients receiving late (after 7 days) plasma exchange was dialysis-free. MLPA showed that 11 patients had heterozygous deletions of exons 3, 5, 6 of CFHR1 and upstream region of exons 1, 2, 3, 6 and intron 4 of CFHR3 gene while four patients had homozygous deletions at the same loci. Two patients had no MLPA-detectable variations.

CONCLUSION

This study reports a high proportion of deletions of exons of CFHR1 & CFHR3 genes in Indian P-aHUS patients detectable by MLPA by copy number variations. This needs confirmation in large multicentre studies. Plasma exchange can be an effective therapy in the non-availability of Eculizumab.

2021 update of the 2012 ICSH Recommendations for identification, diagnostic value, and quantitation of schistocytes: Impact and revisions

In 2012, the International Council for Standardization in Hematology (ICSH) published recommendations for the identification, quantitation, and diagnostic value of schistocytes. In the present review, the impact of these recommendations is evaluated. This work is based on citations in peer-reviewed papers published since 2012. The first 2012 ICSH Recommendations have also been revised to incorporate newly published data in the literature and current best laboratory practice. Recommended reference ranges have been proposed for healthy adults and full-term neonates of 1% or less schistocytes. More than 1% of morphologically identified schistocytes on the blood film are considered suspicious for thrombotic microangiopathy. For preterm infants, a normal level of 5% or less is recommended. The fragment red cell count (FRC) generated by some automated hematological analyzers provides a valuable screening tool for the presence of schistocytes. Specifically, the absence of FRCs can be used as a valuable parameter to exclude the presence of schistocytes on the blood film. The validity and usefulness of microscope schistocytes and automated FRCs, respectively, are discussed in the context of the laboratory diagnostic tests used for thrombotic microangiopathies.

De novo thrombotic microangiopathy in two kidney transplant recipients from the same deceased donor: A case series

Thrombotic microangiopathy (TMA) is a recognized and serious complication of renal transplantation. Atypical hemolytic uremic syndrome (aHUS), a subset of TMA, occurs in the setting of dysregulation of the alternative complement pathway and can cause disease in native kidneys as well as recurrence in allografts. De novo TMA represents a classification of TMA post-transplant in the absence of clinical or histopathological evidence of TMA or aHUS in the native kidney. De novo TMA is a more heterogeneous syndrome than aHUS and the pathogenesis and risk factors for de novo TMA are poorly understood. The association between calcineurin inhibitors (CNI) and de novo TMA is controversial. Anti-complement blockade therapy with eculizumab is effective in some cases, but more studies are needed to identify appropriate candidates for therapy. We present two cases of de novo TMA occurring immediately in recipients from the same deceased donor and provoking the question of whether deceased donor-related factors could represent risks for developing de novo TMA.