Benralizumab for acute thromboembolism in hypereosinophilic syndrome: A case report

Background Hypereosinophilic syndrome is a group of disorders characterized by organ dysfunction caused by hypereosinophilia, which frequently leads to thromboembolic complications with potentially fatal outcomes. Interleukin-5, a key cytokine that promotes the differentiation and activation of eosinophils, has been identified as a therapeutic target. Anti-interleukin-5 antibody therapy has demonstrated efficacy in reducing eosinophil counts and enabling steroid dose tapering in patients with hypereosinophilic syndrome. This report describes the case of a patient with severe thromboembolism associated with hypereosinophilic syndrome during the acute phase who was successfully treated with benralizumab, an anti-interleukin-5 receptor alpha antibody. Case presentation: A 22-year-old woman presented with a persistent cough and was diagnosed with eosinophilic pneumonia and portal vein thrombosis. Although eosinophilic pneumonia improved with corticosteroid therapy, thrombotic complications worsened despite additional anticoagulant treatment. The administration of benralizumab led to marked improvement in thrombosis, resulting in clinical recovery. Conclusions This case suggests that the early administration of anti-interleukin-5 receptor antibody therapy may be a valuable treatment option for refractory thrombosis.