Tumor thrombus formation in two dogs with insulinomas

Abstract

A 9-year-old sexually intact male Staffordshire Bull Terrier and a 9-year-old neutered male Boxer were evaluated for intermittent neurologic signs including muscle tremors, ataxia, episodic collapse, disorientation, and seizures. Both dogs had low blood glucose and high serum insulin concentrations. Results of abdominal ultrasonography were unremarkable for both dogs. Exploratory laparotomy revealed a mass that extended from the body of the pancreas into the pancreaticoduodenal vein in each dog. Marginal resection of pancreatic masses was performed, and tumor thrombi were removed via venotomy in both dogs. Histologic evaluation indicated the masses were pancreatic islet cell tumors with tumor thrombi. Clinical signs resolved following surgical resection of tumors and tumor thrombi, and the dogs were euglycemic during the follow-up period (17 and 45 months after surgery). Although gross tumor thrombus formation has been identified in humans with insulinomas, tumor thrombi have not been previously reported for dogs with insulinomas. Surgical removal of tumor thrombi via venotomy seemed to be well tolerated by the dogs. Tumor thrombus formation did not seem to adversely affect prognosis for the 2 dogs of this report.