[A case of pseudomembranous colitis in a juvenile rheumatoid arthritis patient taking methotrexate].

Pseudomembranous colitis is mainly caused by antibiotics and Clostridium difficile infection. But conditions such as gastrointestinal surgery, antacid medication, anti-neoplastic agent or immunosuppressive agent which influences the normal flora of colon can induce colitis without the administration of any antibiotics. We experienced a 13 year-old male who was taking low-dose methotrexate for juvenile rheumatoid arthritis complained diarrhea and abdominal pain for 3 weeks. Sigmoidoscopic findings revealed diffuse patch yellowish pseudomembranes on the rectum. Histologic finding was compatible to pseudomembranous colitis. His symptom was improved after stop taking methotrexate and the administration of metronidazole. If a patient treated with immunosuppressive agents or antineoplastic agents complains diarrhea, fever or abdominal pain and has not improved with conservative care, pseudomembranous colitis should be taken into account as a differential diagnosis and prompt treatment is required for better prognosis.