Leflunomide-induced colitis in association with enterocutaneous fistula in an immunosuppressed patient with renal transplant and rheumatoid arthritis.

We describe the case of a 68-year-old man who has a complex medical background that included renal transplantation, rheumatoid arthritis and atrial fibrillation. Because of this, he was taking a number of immunosuppressant medications including leflunomide, prednisone and tacrolimus. He had experienced chronic diarrhoea over 18 months which had acutely worsened over the 6 weeks prior to hospital presentation. Recent colonoscopies had been performed to investigate this diarrhoea with biopsies revealing acute and chronic inflammatory changes in the terminal ileum and colon. No infectious cause could be found, with all bacterial and viral stool cultures returning negative. An enterocutaneous fistula had also spontaneously developed through his renal transplant scar in the days preceding hospital admission which complicated the clinical picture. Following dose reduction of leflunomide, there was a significant improvement in the frequency and severity of the patient's diarrhoea. He continues to be managed non-operatively for his fistula as he is at high risk of peri-operative morbidity and mortality.