An Elderly Patient Developed Ulcerative Colitis after SARS-CoV-2 mRNA Vaccination: A Case Report and Review of the Literature.

An 86-year-old man presented to our hospital with symptoms of diarrhea and bloody stool, which had manifested two weeks after receiving his third severe acute respiratory syndrome coronavirus 2 mRNA vaccination. Colonoscopy revealed diffuse, rough-surfaced mucosa extending from the ascending colon to the rectum. Despite attempting probiotic treatment, the patient's condition did not improve, leading to admission. Endoscopic findings at admission worsened. Based on endoscopic and histopathological findings, the patient was diagnosed with ulcerative colitis. Corticosteroids and 5-aminosalicylic acid were administered, and the clinical symptoms improved. Subsequently, the disease worsened during steroid tapering, and filgotinib was added, leading to steroid-free remission.