Finding the needle in a haystack: single-balloon enteroscopy to diagnose diffuse large B-cell lymphoma

A 74-year-old woman who was on warfarin for a past medical history of atrial fibrillation and a mechanical mitral valve was admitted with symptomatic anemia. The patient reported fatigue, shortness of breath, and epigastric abdominal pain, with associated black stools for a week. Her physical examination was unremarkable. Laboratory investigations were notable for a normocytic anemia (hemoglobin 6.2 g/dL), with an international normalized ratio (INR) of 1.6 and a prothrombin time of 19.5 seconds. The patient underwent esophagogastroduodenoscopy and colonoscopy, with there being no evidence of active bleeding. She continued to have persistent drops in her hemoglobin requiring several transfusions during her admission. Subsequent video capsule endoscopy revealed blood intermittently in the mid-to-distal small bowel ([Video 1]). Computed tomography with enterography of the abdomen and pelvis revealed no acute intra-abdominal process. Push enteroscopy was subsequently performed, with examination of the jejunum being normal ([Fig. 1]). Further evaluation with single-balloon push enteroscopy revealed an ulcerated lesion of 1 cm, with no active bleeding in the jejunum ([Fig. 2]). The lesion was biopsied, and the rest of the examination was unremarkable. Biopsies showed an infiltrate of large atypical lymphocytes within the lamina propria of the small bowel with architectural destruction and lymphoepithelial lesions ([Fig. 3] a). PAX-5 immunohistochemical staining identified these atypical lymphocytes to be B cells ([Fig. 3] b). The histology and remaining immunohistochemical stains (not shown) were diagnostic of a diffuse large B-cell lymphoma (DLBCL), activated B-cell subtype.