An Unusual Cause of Diarrhea in an Immunocompromised Patient

Abstract

Question: A 64-year-old man with a history of chronic hepatitis C and alcoholic cirrhosis underwent orthotopic liver transplantation 4.5 months prior. His course was complicated by moderate acute cellular rejection and he was maintained on tacrolimus 2mg twice daily, sirolimus 5 mg/d, prednisone 25 mg/d, and mycophenolate mofetil 1000 mg twice daily (quadruple immunosuppression). Soon after initiation of quadruple immunosuppression, he was transferred to our hospital for 3 weeks of watery, nonbloody diarrhea. He denied nausea or vomiting. The patient did not have any other relevant medical history. On presentation, physical examination was significant for mild, diffuse abdominal tenderness without rebound or guarding. Laboratory workup was notable for thrombocytopenia (platelets 56,000/mL), metabolic acidosis (bicarbonate 14 mmol/L), acute renal failure (creatinine 4.2 mg/dL), and normal liver function tests. Stool culture, ova and parasites, and Clostridium difficile toxin were negative. A colonoscopy was performed, which showed multiple large, shallow ulcers (Figures A and B). Histology revealed colonic mucosa with ulceration, granulation tissue, and mild acute inflammation. Cytomegalovirus and herpes simplex virus immunostains were negative. While in the hospital, the patient developed new generalized tonic clonic seizures. Magnetic resonance imaging of the brain showed a peripherally enhancing mass in the left frontal lobe measuring 3.2 3.1 3.3 cm concerning for an abscess. What is the diagnosis and what would be the next diagnostic step? Look on page 697 for the answer and see the GASTROENTEROLOGY web site (www.gastrojournal.org) for more information on submitting your favorite image to Clinical Challenges and Images in GI.