Malta et al; Malignant Insulinoma in a Crab-Eating Fox (Cerdocyon thous). Braz J Vet Pathol; 2008, 1(1): 25 -27 Brazilian Journal of Veterinary Pathology. www.bjvp.org.br . All rights reserved 2007. 25 Case report Malignant insulinoma in a crab-eating fox (Cerdocyon thous) Marcelo C. C. Malta 1 , Marcela M. Luppi 1 , Raquel G. Oliveira 2 , Ingeborg M. Langohr 3 , Roselene Ecco 2 , and Renato L. Santos 2 * 1 Fundação Zoo-Botânica de Belo Horizonte, Belo Horizonte, MG, Brazil.; 2 Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.; 3 Department of Comparative Pathobiology, Purdue University, West Lafayette, IN, USA. *Corresponding author: Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, 31270-901 Belo Horizonte, MG, Brazil. Phone: 55-31-3409-2239; fax: 55-31-3409-2230 (Email: rsantos@vet.ufmg.br ). Submitted December 13 th 2007, Accepted March 3 rd 2008 Abstract This report describes a case of insulin-secreting pancreatic beta cell carcinoma in a crab-eating fox (Cerdocyon thous). The animal died approximately 60 days after the first clinical signs. At necropsy, a nodule (2 x 3 cm) was observed in the pancreas. Microscopic features were consistent with a pancreatic islet cell carcinoma. By immunohistochemistry, neoplastic cells were strongly positive for insulin and synaptophysin while negative for glucagon. These results supported the diagnosis of insulinoma, which to the best of our knowledge is the first documented case of this tumor in a crab-eating fox. Keywords: Cerdocyon thous, crab-eating fox, insulinoma. Insulinomas are insulin-secreting pancreatic adenomas or carcinomas derived from beta cells. These tumors are the most common tumors arising from the pancreatic islets (1). This neoplasia is often associated with hyperinsulinism and hypoglycemia, and a large proportion is malignant (7, 11). Insulinomas occur most frequently in dogs (2, 5, 7, 11) and ferrets, less frequently in cattle, and rarely in cats (1, 12). Middle-aged or older, large-breed dogs have a higher risk of developing these tumors, while both sexes are equally affected (1, 7, 11). Younger dogs usually have a shorter survival time than older dogs, and the maximum survival period is approximately 3 years (2, 5), which is influenced by post surgical medical therapy (9). The occurrence of insulinoma in wild canids has been rarely documented with one single report of insulinoma in a red fox (Vulpes vulpes) arising from an ectopic pancreas (6). This report describes a case of insulinoma in a female adult (more than 10 years of age) crab-eating fox (Cerdocyon thous) kept in captivity at the Fundação Zoo- Botânica (Belo Horizonte, MG, Brazil). In October of 2005, the animal had apathy, distended abdomen, and splenomegaly. A nodule of approximately 2 cm in diameter was detected in the gastric region by abdominal palpation. During the first clinical examination, CBC values were within normal range, blood glucose was 88 mg/dl, alkaline phosphatase was 111 U/L, and urinalysis revealed leucocytes and triple phosphate crystals. One month later the clinical condition worsened, with proteinuria, anemia, and leucopenia. The animal died approximately 60 days after the first clinical examination. Grossly, the animal had poor body condition and pale mucous membranes. The most significant finding was a large predominantly tan nodule (2 x 1 cm) at the pancreas, which was solid and lobulated (Fig. 1). In addition, the animal had mild pulmonary edema, splenomegaly, enlargement of mesenteric lymph nodes, and petechial hemorrhages in the mucosa of the stomach and urinary bladder. Histologically, the pancreatic nodule consisted of a locally invasive, partially encapsulated and well demarcated epithelial neoplasm. The neoplastic cells were arranged in cords supported by delicate septa of fibrovascular stroma (Fig. 2). Occasional