Insulin‐Secreting Pancreatic (Islet Cell) Carcinoma in a Cat

Abstract

A functional, insulin-secreting pancreatic (islet cell) carcinoma was diagnosed in a 17-year-old male Siamese cat. Diagnosis was made on the basis of clinical signs (i.e., seizures and stupor) that resolved temporarily after correction of hypoglycemia with feeding or intravenous administration of glucose, the finding of an inappropriately increased serum insulin concentration in the face of hypoglycemia, and prolonged resolution of hypoglycemia after surgical removal of the tumor. Primary islet cell tumor of the pancreas was confirmed by biopsy. The cat died 18 months later, and necropsy revealed metastases to regional lymph nodes and liver. INSULIN-SECRETING pancreatic (islet cell) tumors leading to hypoglycemia are well recognized in human beings,' dogs,*-' and ferrets,6 but they have not been well documented in cats. This report describes the clinical, serum biochemical, and pathologic findings in an elderly cat with an insulin-secreting tumor of the pancreas. Materials and MethodsSerum insulin was measured with a commercial radioimmunoassay kit.* Assay of serial dilutions of a feline serum pool containing increased insulin concentrations (approximately 400 pmol/L) resulted in inhibition curves with slopes parallel with the standard curve. Accuracy was determined by adding various quantities of purified pork regular insulin to a feline serum pool containing an undetectable concentration of insulin; analysis of the resulting data revealed an average recovery of 94%. The sensitivity of the insulin assay was 35 pmol/L. The intra-and interassay coefficients of variation were 8.1% and 1476, respectively. Immunocytochemical staining was done with the avidin-biotin-peroxidase complex immunoperoxidase method as previously described,'.* with polyclonal antibodies against guinea pig insulin,t porcine glucagon,? human gastrin,? pancreatic polypeptide,? and somatostatin? and bovine neuron specific enolase,? and chromogranin A.S Case ReportA 17-year-old male castrated Siamese cat was examined because of previously diagnosed hypoglycemic seizures. The seizures were grand mal, unassociated with meals, and responsive to oral corn syrup. The seizures had begun 18 months previously and were increasing in frequency.Three and 1 1 months before examination, the cat had two episodes of severe regenerative anemia (PCV = <lo%). Tests for FeLV, FIP, toxoplasmosis, and hemobartonella were negative. During hospitalization for the second episode of anemia, the cat was found in a stupor with a blood glucose concentration of 25 mg/dl (normal, 70-1 50 mg/dl). The cat responded well to intravenous administration of dextrose, and was discharged with instructions to the owner to feed frequently and to administer corn syrup as needed to control the seizures. Prednisone (5 mg, once daily, orally) was also given for 1 month. During prednisone administration, the seizures decreased in frequency and severity but then increased

Cellular and Molecular Characterization of a Feline Insulinoma

“…Insulinoma is an uncommon tumor of cats. Previous reports of feline insulinoma have focused on clinical and histological features of these tumors 1–5 . In the current study, immunohistochemical analysis demonstrated the production of multiple peptide hormones by the tumor cells.…”

“…Insulinomas in cats are rare, with fewer than a dozen well‐documented cases reported in the literature. In cats, the reported clinical signs usually are related to tumor functional capacity and include lethargy, weakness, and seizures 1–5 …”

Endocrine/Neuroendocrine System

“…Commonly affected breeds include Boxers, German Shepherds, Irish Setters, Poodles, Fox Terriers, Collies, and Labrador Retrievers, but these results may be biased by the popularity of several of these breeds (Goutal et al, 2012). These tumors are identified with some frequency in the ferret and rarely in the cat (Capen, 2002;Hawks et al, 1992). The cytologic appearance of insulinomas is typical of other endocrine tumors.…”

Beta-Cell Neoplasia: Insulinoma

“…Insulin-secreting beta-cell tumors are rare in cats with only a few single cat case reports in the literature (McMillan, 1985;O'Brien et al, 1990;Hawks et al, 1992;Kraje, 2003;Greene and Bright, 2008) and one additional report in which the beta-cell tumor was an incidental finding at necropsy in a cat with ductal pancreatic adenocarcinoma (Carpenter et al, 1987). We have seen only two cats with beta-cell neoplasia during the past three decades, in contrast to more than 150 dogs with the disease during the same time interval.…”