Ileo-colonic infiltration in acute myeloid leukemia.

A 66-year-old woman with diffuse, persistent colicky abdominal pain for the past 2 months with postprandial abdominal distension, weight loss (3kg), asthenia, anorexia, and sporadic vomiting attended the emergency room. Blood investigations revealed hemoglobin 11.6g/dL, platelets 82×109/L, C-reactive protein 135mg/dL, and potassium 3.2mEq/L. Computed tomography (CT) revealed thickening of the ileal wall in various intestinal loops with proliferation of mesenteric fat and increased vascularization (involving 2cm of the terminal ileum and 40cm of the proximal ileum), suggestive of Crohn disease. The patient’s abdominal pain subsided after 3 days of antibiotics (intravenous ceftriaxone 2g once a day and metronidazole 500mg three times a day) and an ileocolonoscopy revealed aphthous erosion in the ascending colon and edema, erythema, and three ulcers in the terminal ileum with irregular, elevated borders (●" Fig.1). Histological examination of the ileal and colonic biopsy specimens showed profuse blast-cell mucosal infiltration (●" Fig.2a). Leder staining and myeloperoxidase immunostaining (●" Fig.2b) confirmed the myeloid nature of the neoplastic cells. A bone marrow biopsy confirmed the diagnosis of acute myeloid leukemia (AML). The French-American-British (FAB) subtype of leukemia in this case was M1. The patient was started on chemotherapy according to the AML-17 protocol with a positive hematological response. She became asymptomatic and a repeat colonoscopy with biopsies showed no signs of disease involvement on histological examination. Clinically significant extramedullary involvement of the gastrointestinal tract in leukemia is rare [1–5]. Our case is particularly unique because the diagnosis was established following colonoscopy, and serves as an alert for clinicians and endoscopists to consider rare pathologies that may clinically and endoscopically mimic more common diseases in the differential diagnosis.