Histopathologic aspects of pancreatic islet cell tumor in a dog

A 12-year-old 4.3 kg intact female Terrier presented with a history of lethargy, anorexia, and melena for one month. The animal was dull and depressed. Dermatologic examination revealed some focal erythematous, crusty, and papulopustular lesions over the ventral abdomen. Ultrasonographic evaluation displayed an abnormal parenchymal pattern of the liver, which was noticed in the cranial part of the abdomen with diffuse hepatic involvement with irregular, hypoechoic, and heterogeneous ill-defined areas [a honeycomb-like echotexture]. Lateral thoracocervical radiograph showed numerous well-defined, small lytic lesions [polyostotic punched-out lesions] in the dorsal spinous process of axis bone in C2-C5 and pelvis that were likely metastatic lesions. Despite hospitalization and treatment, the dog died after 2 weeks and a necropsy was performed. At postmortem examination, a 5-cm mass was observed in the pancreas adjacent to duodenal loops which was finally diagnosed as a pancreatic tumor. Abnormal laboratory findings included elevated blood urea nitrogen, creatinine, cholesterol, total bilirubin, aspartate aminotransferase, alkaline phosphatase, gamma-glutamyltranspeptidase, and calcium. Histopathological examination of the affected pancreas revealed neoplastic cells which were arranged mainly as solid nests or clusters and the amounts of the tumor stroma among the cellular clusters or individual neoplastic cells were scant. According to an immunohistochemical study which was positive for chromogranine A, the condition was diagnosed as a pancreatic islet cell tumor. Although rare, pancreatic islet tumors should be included in the differential diagnosis of abdominal discomforts, pancreatic inflammation, and hepatopathies. The final diagnosis of the tumor is achieved by combining imaging techniques and advanced histopathologic evaluations.