The efficacy of JAK inhibitors in adult eosinophilic colitis with atopic dermatitis; four cases report.

We herein present four cases of Eosinophilic colitis (EoC) in adult patients who were successfully treated with a Janus kinase (JAK) inhibitor. Case 1 is a 23-year-old female who was treated with baricitinib (BAR, 4 mg, once a day) for atopic dermatitis (AD). Colonoscopy (CS) initially did not reveal any significant abnormalities. However, she underwent another CS when she underwent a food challenge test involving wheat without baricitinib medication. During this procedure, the CS subsequently leading to her diagnosis of EoC based on eosinophil infiltration. Case 2 is a 26-year-old man whereas Case 3 is a 40-year-old man. Both patients were started on upadacitinib (UPA, 15 mg, once daily) for the treatment of AD. Their abdominal symptoms improved, and colonic histology revealed the disappearance of eosinophils. Case 4, on the other hand, is a 29-year-old woman who was also started on UPA (15 mg, once daily). Her skin lesions and abdominal symptoms also improved within 2 weeks. To the best of our knowledge, this is the first novel clinical observational case report on the efficacy of JAK inhibitors in treating adult patients with both EoC and AD.