Radiographic Diagnosis of Diphyllobothriasis: Hiding in Plain Sight

Abstract

2482 Figure 1. Axial, coronal, and sagittal CT images depicting a curvilinear filling defect in the small bowel concerning for intestinal tapewormDiphyllobothriasis is diagnosed by identification of proglottids in the stool or by direct endoscopic visualization of a worm. We describe a case in which an intestinal tapeworm is stumbled upon via abdominal imaging. An 80 year smoker with idiopathic pulmonary fibrosis presented to a VA gastroenterology clinic for dyspepsia unresponsive to H2 blockers and proton pump inhibitors. He reported 3 months of progressive abdominal fullness, bloating, intermittent loose stools, and anorexia leading to 20-25 pounds of weight loss. Physical exam showed conjunctival pallor and mild abdominal distension. A CBC demonstrated macrocytic anemia. Vitamin B12 level was 90pg/ml (nl 213-816 pg/ml). Serum anti-parietal cell and antiintrinsic factor antibodies were negative, and serum gastrin and folate levels were normal. He refused endoscopy. Contrasted CT of the abdomen and pelvis demonstrated a curvilinear filling defect from the proximal jejunum through most of the visualized small bowel. Three stool ova and parasite (O&P) samples were collected; two demonstrated proglottids characteristic of Diphyllobothrium. His symptoms resolved after a dose of praziquantel (10mg/kg), and repeat stool O&P after one month proved eradication. The frequency of parasite detection via stool O&P has been reported at ˜20% when examining a single sample, compared to ˜50% when two or more are examined. Likewise, examining two or more specimens increases the sensitivity from 75% to 92%. Uniquely, the initial hint of a parasite in our patient was found via imaging. Radiographic findings of intestinal tapeworms are rare, and CT in the presence of known infection does not always demonstrate a parasite. The first two cases of tapeworm visualization via capsule endoscopy were recently reported. The focused differential for this elderly smoker with dyspepsia and weight loss included peptic ulcer disease and gastrointestinal malignancy. Screening labs for gastrinoma and pernicious anemia were negative. This patient did not report typical risk factors for diphyllobothriasis, including travel to endemic regions and raw fish consumption. After the patient refused endoscopy, CT revealed distinctive findings concerning for intestinal tapeworm, confirmed by observation of proglottids in the stool. Macrocytic anemia in the setting of weight loss and dyspepsia requires a workup for malabsorption, malignancy, and, though rare, parasitic infection.