Giant duodenal diverticulum associated with lymphoma in a Dog

A 2-year old, 14-kg intact female Jindo dog was referred with a 1-month history of anorexia, weight loss, lethargy, and melena. On physical examination, the patient had pale mucous membranes and a low body condition score. Radiographic and ultrasonographic examinations revealed a large mass containing mineral density materials and peritoneal free fluid within the abdominal cavity. Fine-needle aspiration of the mass-like lesion was performed and the cytologic interpretation was gastrointestinal lymphoma. The diagnosis was gastrointestinal lymphoma with septic peritonitis. The decision was taken to resect the mass. Abdominal exploration revealed a large amount of septic fluid and a hollow structural mass adherent to the omentum on the antimesenteric duodenal border. Duodenal resection and anastomosis was performed. Histopathologic examination noted largely effaced tissue architecture and confirmed lymphoma. Immunohistochemical staining indicated that the mass was a high-grade B-cell lymphoma. This is the first description of canine duodenal diverticulum with malignancy.