Insulinoma in a cat

Abstract

A 14-year-old domestic shorthair cat was presented with hypoglycaemia and seizures of several weeks duration. Bloodwork revealed hypoglycaemia (1.83 mmol/l; reference range 4.22-8.05 mmol/l) with concurrent normal insulin levels (171 pmol/l; reference range 72-583 pmol/l). An insulinoma was suspected and medical and dietary management were attempted with minimal success. An exploratory laparotomy was performed and a single, well-defined mass was found within the left lobe of the pancreas. The mass was removed and histologically classified as an islet cell carcinoma, consistent with an insulinoma. The cat had an episode of presumed postoperative pancreatitits, but recovered with appropriate treatment. The cat has had no clinical signs of recurrence of greater than 32 months postsurgery. There are only four cases of insulinoma in cats reported in the literature. All prior insulionomas reported were in older cats and were malignant in character, which is similar to the reports in the dog. This case is unique because of the apparent lack of local recurrence and development of metastatic disease, leading to the prolonged survival.

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.…”

“…Insulin expression in feline insulinomas, however, is variable and has been described as patchy to diffuse, 2,4,10 with >50% of cells staining insulin‐positive in some tumors 2 and no insulin staining reported in 1 tumor 1 . Despite the apparent variation in tumor insulin production, the hypoglycemia and hyperinsulinemia that characterize the clinical presentation of cats with insulinoma indicate that tumor cells retain the capacity for insulin release 1–5 …”

“…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 …”

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.…”

Hyperinsulinaemic, hypoglycaemic syndrome due to acquired nesidioblastosis in a cat

“…9 The age of onset may have provided a clue to this non-neoplastic disease, as this cat was much younger than all previously reported cases of feline insulinoma (all were >12 years of age at diagnosis). 10,11 …”