The Elusive Colonic Ulcer in Mycophenolate Mofetil Colitis – Is It Inflammatory or Neoplastic?

Introduction and Aims: Gastrointestinal toxicity resulting in diarrhea is a common side effect in patients taking Mycophenolate mofetil (MMF). The challenge is in making the decision to pursue further workup being mindful of malignancy and opportunistic infection in these group of immunosuppressed individuals, or to stop the offending agent and observe. Colonoscopy with biopsies remains the gold-standard diagnostic tool to establish the underlying etiology, but lesions found are often non-specific especially when there is ongoing active inflammation. We report a case of an inflammatory colonic ulcer that turned out to be neoplastic which healed with time making it difficult to locate on subsequent colonoscopies.

Case Presentation: A 77-year-old man with a background history of heart transplant was referred for endoscopic resection to a solitary high-grade dysplastic tubular adenomatous lesion in the hepatic flexure. This was detected incidentally while he was being investigated for persistent diarrhea. A solitary ulcer on a background of colitis was visualized on index colonoscopy. The colitis was attributed to MMF. The MMF was stopped and his symptoms improved. A repeated colonoscopy performed 6 weeks later revealed no obvious abnormalities. Upon discussion with the patient, he was referred on to an expert endoscopy center for reassessment. In this instance, a 9 mm subtle, flat and mildly erythematous lesion was detected. We were able to define and characterize the lesion better using Narrow Band Imaging. An Endoscopic Submucosal Dissection was then carried out and the lesion resected in an en-bloc fashion. Histopathological evaluation revealed this to be an intramucosal adenocarcinoma.

Conclusion: In immunosuppressed patients, given the atypical and often subtle presentation of colon cancers, it is important to be extra vigilant and biopsy all suspicious lesions, particularly solitary ulcers. It is worthwhile to tattoo an area distally to aid in identification if the area needs to be reevaluated or resected at a later date.