Two cases of atypical hemolytic uremic syndrome (aHUS) and eosinophilic granulomatosis with polyangiitis (EGPA): a possible relationship

A fatal eosinophilic granulomatosis with polyangiitis case presenting intracerebral hemorrhage and thrombocytopenia

We report the case of a patient with eosinophilic granulomatosis with polyangiitis and unexplained thrombocytopenia that culminated in a fatal intracerebral hemorrhage. Because vessel damage associated with thrombocytopenia could be the leading cause of fatal hemorrhage, more urgent treatment of thrombocytopenia should be performed in such cases.

Complement Factor I Gene Variant in an Atypical Hemolytic Uremic Syndrome Triggered by Hypereosinophilia Syndrome

Atypical hemolytic uremic syndrome (aHUS) is a condition characterized by acute kidney injury (AKI), thrombocytopenia, and microangiopathic hemolytic anemia secondary to complement pathway dysregulation. Several triggers have been identified as causing aHUS in genetically susceptible patients; however, hypereosinophilia syndrome (HES)-triggered aHUS has not been reported. In this article, we present a case of aHUS presented with generalized urticarial rashes and angioedema. The initial investigations revealed hypereosinophilia (maximal absolute eosinophil count of 6,840 cells/µL) with normal bone-marrow analyses; hence, idiopathic HES was diagnosed. During hospitalization, the patient developed convulsion, stuporous, and full-blown thrombotic microangiopathy (TMA), with AKI requiring temporary hemodialysis. A kidney biopsy confirmed the existence of renal TMA. Next-generation sequencing of the coding regions of aHUS-related genes was performed, revealing an underlying complement factor I (CFI) deficiency, a heterozygous variant p.P64L of CFI gene. The patient was successfully treated with high-dose steroids and extended duration of plasmapheresis.

Atypical Hemolytic Uremic Syndrome After Kidney Transplantation: Lessons Learned From the Good, the Bad, and the Ugly. A Case Series With Literature Review

Atypical hemolytic uremic syndrome (aHUS) after kidney transplantation is rare and carries a grave outcome. We present a single-center experience of all aHUS cases since the program's inception. Six patients were diagnosed with aHUS, all after kidney transplants, except for 1 patient. All had nonreactive crossmatches. Delayed graft function (DGF) occurred in 2 patients. Five patients developed aHUS after transplant; 4 (80%) of these patients manifested aHUS ≤ 14 days. All were confirmed by allograft biopsy. Genetic testing was abnormal in all patients except for 1 patient. Actual patient and graft survival during the first year was 100% and 83.3%, respectively. A single graft was lost early in the study secondary to aHUS (eculizumab was not used in the treatment process). Prophylactic and therapeutic use of eculizumab salvaged all other cases. At 1 year, mean creatinine level was 1.9 mg/dL (range, 1.3-2.5). After 6 months of eculizumab treatment (halted in 2 cases) 1 patient had recurrence 2 months later and eculizumab was restarted. However, graft function continued to worsen, and the graft was ultimately lost at 20 months after kidney transplantation. High index of suspicion, prompt diagnosis, and utilization of eculizumab are key to successful salvage of allografts in cases of aHUS after kidney transplantation. aHUS can be prevented by prophylactic use of eculizumab. It still needs to be determined when and if eculizumab therapy can be safely discontinued.

Thrombotic microangiopathy in a patient with eosinophilic granulomatosis with polyangiitis: case-based review

The correct diagnosis, classification and therapeutic management of thrombotic microangiopathies (TMA) continue to be a challenge for the clinician. We report a rare case of eosinophilic granulomatosis with polyangiitis (EGPA) as a trigger for complement-mediated TMA in a 57-year-old man who was successfully treated with corticoids, cyclophosphamide and therapeutic plasma exchange. Additionally, we review few other cases reported in the literature and the pathophysiological pathway of association between TMA and EGPA. We found that the mutual relationships between the inflammation triggered by vasculitis, the exacerbated complement activation, together with hypereosinophilia and endothelial damage seem to be the key in explaining the connection between both entities. We suggest that an understanding of the multi-causal nature of TMAs is crucial for the correct diagnosis and treatment of these patients.

Eosinophilia and Kidney Disease: More than Just an Incidental Finding?

Peripheral blood eosinophilia (PBE), defined as 500 eosinophils or above per microliter (µL) blood, is a condition that is not uncommon but often neglected in the management of patients with chronic kidney disease (CKD), acute kidney injury (AKI), or patients on renal replacement therapy (RRT). The nature of PBE in the context of kidney diseases is predominantly secondary or reactive and has to be distinguished from primary eosinophilic disorders. Nonetheless, the finding of persistent PBE can be a useful clue for the differential diagnosis of underdiagnosed entities and overlapping syndromes, such as eosinophilic granulomatosis with polyangiitis (EGPA), IgG4-related disease (IgG4-RD), acute interstitial nephritis (AIN), or the hypereosinophilic syndrome (HES). For patients on RRT, PBE may be an indicator for bio-incompatibility of the dialysis material, acute allograft rejection, or Strongyloides hyperinfection. In a subset of patients with EGPA, eosinophils might even be the driving force in disease pathogenesis. This improved understanding is already being used to facilitate novel therapeutic options. Mepolizumab has been licensed for the management of EGPA and is applied with the aim to abrogate the underlying immunologic process by blocking interleukin-5. The current article provides an overview of different renal pathologies that are associated with PBE. Further scientific effort is required to understand the exact role and function of eosinophils in these disorders which may pave the way to improved interdisciplinary management of such patients.