Adult-onset severe paroxysmal cold hemoglobinuria after COVID-19 successfully treated with sutimlimab.

Paroxysmal cold hemoglobinuria (PCH) is a form of cold autoimmune hemolytic anemia characterized by the presence of the Donath-Landsteiner antibody, which triggers complement-mediated intravascular hemolysis when the body temperature changes from cold to warm. PCH occurs primarily in children as a rare, self-limiting disease following viral infections. In contrast, adult-onset PCH is very rare and associated with a diverse range of underlying conditions, which complicates its management and treatment. We describe a case of adult-onset PCH following COVID-19, effectively managed with a single dose of sutimlimab, a selective classical complement pathway inhibitor. This intervention was performed during a life-threatening hemolytic crisis, at a time requiring swift decision-making when specific tests to differentiate from other hemolytic anemias were not readily available. This case illustrates the potential of using a single dose of sutimlimab to manage life-threatening hemolytic crises in PCH, highlighting the significance of inhibiting the classical complement pathway.