A Unique Case of Rituximab-Induced Crohnʼs Disease: A Case Report and Review of Literature

Abstract

Rituximab is a humanized monoclonal antibody against CD20 which is a mainstay of therapy for a wide variety of B cell malignancies. There are only two reported cases of Crohn's disease following treatment with Rituximab in the literature. We present a very unique case of a 58 year old female who was treated with Rituximab, Cyclophosphamide, Doxorubicin, Vincristine and Prednisolone (R-CHOP) regimen for initial diagnosis of follicular cell lymphoma of the tonsils. She was treated with prolonged maintenance Rituximab treatment for a recurrence of the lymphoma two years later and the treatment was continued for two and a half years. Three years later she was noted to have increased activity in the terminal ilium and mesenteric lymph nodes on a routine positron emission tomography (PET) scan. At that time, she was asymptomatic and refused any further workup or treatment. Another PET scan done two years later showed enlarged mesenteric lymph nodes with increased activity in the terminal ileum and the spleen. A colonoscopy performed at that time revealed inflammation with extensive ulceration in the terminal ileum. Biopsy demonstrated severely active chronic nonspecific ileitis with ulceration and a small granulomatous lesion. She was then re-treated again with 4 cycles of rituximab for a presumed recurrence. Two months after the treatment, she developed severe abdominal pain leading to an emergency room visit. A computerized tomography (CT) scan showed thickening in the distal descending colon as well as the entire sigmoid colon with surrounding fat stranding. She was treated with oral ciprofloxacin and metronidazole for 10 days with improvement in the symptoms. In a follow-up PET scan done a month later, the mesenteric adenopathy resolved but the activity in the terminal ileum was unchanged and there was new activity in the sigmoid colon. The patient refused further endoscopic examination, however the PET scan findings of worsening of the bowel inflammation and resolution of the adenopathy strongly suggests Rituximab induced Crohn's disease. This case portrays the importance of being alert to the possibility of Crohn's disease occurring as complication of Rituximab treatment. This case is unique as the Crohn's disease occurred almost three years after the initial Rituximab treatment. Management of Crohn's disease in patients with a history of lymphoma can be challenging due to the risk of lymphoma from Anti-TNF and immunomodulatory treatments.Figure: PET Scan showing increased uptake in the mesenteric lymph nodes and terminal ileum.Figure: Colonoscopy image of the terminal ileum.