Rituximab-Induced Crohn's Disease-like Colitis Following Treatment for Post-transplant Lymphoproliferative Disorder in Chronic Active Epstein-Barr Virus Infection: A Case Report.

A man in his 40s with chronic active Epstein-Barr virus infection (CAEBV) underwent allogeneic hematopoietic stem cell transplantation twice and developed post-transplant lymphoproliferative disorder (PTLD), confirmed by Epstein-Barr virus (EBV)-encoded small RNA in situ hybridization. Rituximab treatment achieved complete EBV clearance. However, he subsequently developed longitudinal colonic ulcers despite negative EBV RNA staining and undetectable whole-blood EBV DNA. The endoscopic findings suggested Crohn's disease-like colitis. Patients with graft-versus-host disease (GVHD), recurrent PTLD, cytomegalovirus enteritis, or vasculitis were excluded. Treatment with an infliximab biosimilar induced clinical and endoscopic remission. This case highlights rituximab-associated Crohn's colitis as a rare but important complication.