Unusual Cause of Tarry Stool: What Do You Think?

Abstract

Question: A 52-year-old man, who was in good health, presented with a 4-month history of tarry stool, abdominal pain, and weight loss. The patient denied history of inflammatory bowel disese and recent antibiotic use. His abdomen was soft, with mild periumbilical tenderness. There was no organomegaly. Laboratory studies showed red blood cell count 3.02 × 1012/L (normal range 4.3–5.8 × 1012/L), leukocyte count 6.57 × 109/L (normal range 3.5–9.5 × 109/L), platelet count 347 × 109/L (normal range 125–350 × 109/L), hemoglobin 66 g/L (normal range 130–175 g/L), aspartate transaminase 15 U/L (normal range 15–40 U/L), alanine transaminase 7 U/L (normal range 9–50 U/L), total serum protein 49 g/L (normal range 65–85 g/L), and serum albumin 27 g/L (normal range 40–55 g/L). Urine tests were normal. Esophagogastroduodenoscopy was normal, with multiple biopsies showing no abnormality in histopathology. Colonoscopy revealed patchy erythema throughout the colon without active hemorrhage (Figure A). Eight biopsies were taken from the ascending colon, transverse colon, descending colon, and sigmoid colon. Contrast-enhanced abdominal computed tomography showed thickened and dilated ileal loops (Figure B). A double-balloon retrograde enteroscopy revealed numerous patchy areas of denuded and ulcerated ileal mucosa (Figure C), the outline of which was graphically outlined with methylene blue staining (Figure D). Four biopsies were taken from the ileum. Screening was negative for serum tumor markers and the following autoantibodies: anti–double-stranded DNA, anti-nuclear antibody, anti-SSA/Ro, anti-SSB/La, anti–liver/kidney microsomal type 1, anti–Scl-70, anti–smooth muscle antibody, anti–U1-snRNP, anti-mitochondrial antibodies, anti-SmD1, cytoplasmic anti-neutrophil cytoplasmic antibody, and peri-nuclear anti-neutrophil cytoplasmic antibody. Electrocardiography and chest computed tomographic (CT) scan were normal. Biopsies of the colon and small intestine (hematoxylin and eosin staining) revealed the findings shown in Figure E.