Asymptomatic colitis induced by low-dose methotrexate

A woman aged 77 years with a history of rheumatoid arthritis (RA) presented with inflammatory colitis confined to her rectum, which was incidentally found by a screening colonoscopy. Histopathological examination of colonic biopsies showed non-specific inflammatory infiltrates of lymphocytes, the cause of which was unknown. She had been diagnosed with RA 5 years before, and she was receiving methotrexate 6 mg weekly, to which tocilizumab had been added 4 years earlier, which achieved stable control of her disease. She had no gastrointestinal symptoms or other health problems. Tocilizumab-induced colitis was considered likely, and the drug was discontinued. Metronidazole was also prescribed because of possible Clostridium difficile-associated colitis. 3 months later, a repeat colonoscopy showed no improvement of the colitis. The methotrexate was also discontinued, and folinic acid was prescribed daily for 2 weeks, leading to complete resolution of the colitis observed at repeat colonoscopy.