Approach to the differential diagnosis of gastrointestinal complications of bone marrow transplantation (BMT):
- Timing: Graft versus host disease + typhlitis occur up to 30 days after BMT, pseudomembranous colitis occurs any time after BMT
- Sites: Graft versus host disease involves esophagus to rectum, typhlitis involves terminal ileum / cecum / ascending colon, pseudomembranous colitis involves entire colon
- Imaging: Graft versus host disease has mild bowel wall thickening and halo sign, typhlitis has moderate bowel wall thickening and pneumatosis, pseudomembranous colitis has marked bowel wall thickening and accordion sign
- Clinical: Graft versus host disease has skin / liver / spleen / gall bladder involvement, typhlitis has decreased white blood cell count, pseudomembranous colitis has positive Clostridium difficile toxin
Pediatric Imaging 