Cytomegalovirus Colitis during Budesonide Therapy for Ulcerative Colitis

Budesonide is recommended for mild-to-moderate ulcerative colitis (UC); however, cytomegalovirus (CMV) colitis may still emerge during therapy. We report the case of a 69-year-old woman with left-sided UC who developed worsening diarrhea and hematochezia while receiving budesonide rectal foam and MMX. Colonoscopy revealed longitudinal, undermined, and "double-tracked" ulcers in the rectosigmoid. CMV pp65 antigenemia was positive, and immunohistochemical staining of a biopsy specimen revealed CMV-infected cells. Oral valganciclovir was initiated, leading to rapid improvement, with antigenemia converting to negative; follow-up endoscopy showed shallower ulcers. This case illustrates that locally acting budesonide MMX does not eliminate the risk of CMV colitis, and viral reactivation can occur even during its use. Accordingly, when clinical worsening occurs during budesonide MMX therapy, early CMV testing should be considered to avoid unnecessary escalation to systemic corticosteroids or advanced agents.