Therapeutic Plasma Exchange for Eculizumab-refractory Peripheral Cyanosis in Pediatric Anti-factor H Atypical Hemolytic Uremic Syndrome: A Rare Case Report

Background/aim: Atypical hemolytic uremic syndrome (aHUS) is a rare complement-mediated thrombotic microangiopathy characterized by dysregulation of the alternative complement pathway, leading to microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury.Anti-complement factor H antibody-associated aHUS represents a distinct subset with potentially severe disease manifestations.Peripheral ischemic complications are rare in pediatric patients and may indicate severe ongoing microvascular injury despite standard therapy.We report a rare pediatric case highlighting the role of therapeutic plasma exchange (TPE) as an adjunctive treatment in refractory disease.Case description: A 3-year-10-month-old boy with anti-complement factor H antibody-mediated aHUS presented with progressive peripheral cyanosis and features of thrombotic microangiopathy.Despite early initiation of eculizumab and renal replacement therapy, the patient developed persistent hemolysis and worsening digital ischemia.Given the ongoing disease activity and severe extrarenal manifestations, therapeutic plasma exchange was initiated.Following TPE, the patient showed marked clinical improvement with resolution of peripheral ischemia and significant biochemical improvement in hemolytic parameters.Conclusion: This case highlights that severe extrarenal manifestations such as peripheral ischemia may occur in anti-factor H antibody-mediated aHUS and can persist despite complement inhibition therapy.In such scenarios, therapeutic plasma exchange may serve as an effective adjunctive treatment to control ongoing hemolysis and improve clinical outcomes.Clinical significance: Early recognition of refractory hemolysis and ischemic complications in pediatric aHUS is essential for timely therapeutic intervention.Adjunctive use of therapeutic plasma exchange may help remove pathogenic antibodies and complement components, thereby stabilizing disease activity and preventing further microvascular injury in selected patients.