Hypereosinophilic syndrome presenting as coagulopathy

BACKGROUND: Hypereosinophilic syndrome (HES) is an extremely uncommon group of disorders. It rarely presents with coagulopathy without cardiac involvement. CASE PRESENTATION: A 33-year-old previously healthy male with no history of atopic disease presented with abdominal pain, hematochezia, peripheral eosinophilia as high as 10,000 eos/µL, right and left portal vein, mesenteric, and splenic vein thrombi with ischemic colitis resulting in hemicolectomy and small bowel resection. Despite an extensive workup for primary and secondary etiologies of hypereosinophilia by hematology/oncology, infectious disease, rheumatology and allergy/immunology, no other clear causes were identified, and the patient was diagnosed with idiopathic HES. His eosinophilia was successfully treated with high-dose oral corticosteroids (OCS) and subsequently transitioned to anti-IL-5-receptor therapy with benralizumab. He has continued this treatment for over a year with no recurrence of eosinophilia or thrombosis while on benralizumab. CONCLUSION: In patients with an unexplained coagulopathy and eosinophilia, eosinophilic disorders such as HES should be considered. Corticosteroid-sparing agents, such as benralizumab show promise for successfully treating these patients.