Scintigraphic diagnosis of insulinoma in a dog

Diagnostic Imaging for Assessment of the Endocrine System in Exotic Animals

Diagnostic imaging can provide essential evidence supporting the diagnosis of endocrine diseases in exotic companion animals. The specific modality chosen depends on species, specific disease process/organ affected, equipment availability, and often, cost to the owner. While radiography is widely available in veterinary practices, the sensitivity for visualization of endocrine organs is low. Therefore, ultrasonography, computed tomography, or MRI may be preferred. Other specialized imaging modalities are useful for specific disease processes, such as nuclear scintigraphy and PET. This article compiles current evidence for diagnostic imaging of the endocrine system in exotic animals, organized by imaging modality, species, and disease process.

Endocrine Diagnostics for Exotic Animals

Endocrine disease in exotic species is less common than in small animals. Nevertheless, the diagnostic principles used in small animals can be adapted to evaluate endocrine disease in many of the exotic species although species-specific aspects need to be considered. This article covers important diseases such as thyroid dysfunction in reptiles and birds, hyperthyroidism in guinea pigs, and hyperadrenocorticism in ferrets. Glucose metabolism in neoplasms affecting normal physiology, such as insulinoma in ferrets and gastric neuroendocrine carcinoma in bearded dragons, is discussed. Calcium abnormalities, including metabolic bone disease in reptiles and hypocalcemia in birds, are also covered.

Intrapancreatic accessory spleen mimicking pancreatic insulinoma with intrapancreatic metastasis in a cat

An 11-year-old neutered male Domestic Shorthair cat presented with a 3-month history of hypoglycemia, two episodes of seizure, and intermittent tick-like signs. Serum biochemistry revealed severe hypoglycemia associated with high insulin concentrations. Dynamic abdominal computed tomography (CT) indicated two pancreatic masses, which were enhanced most during the late arterial phase but had different degrees and variations of attenuation. Partial pancreatectomy was performed. Histopathology and immunohistochemistry confirmed that one mass was an insulinoma and the other was an ectopic splenic tissue, consistent with the differences in imaging findings. When an intrapancreatic lesion with hyper-attenuation on dynamic abdominal CT is detected, not only insulinoma or metastasis of malignancies but also intrapancreatic accessory spleen (IPAS) should be considered as differential diagnoses.

Use of contrast-enhanced ultrasonography for the detection of a feline insulinoma

Case summary

A 14-year-old cat was presented with a 2-week history of ataxia, seizure-like episodes, vomiting and weight loss. Serum biochemistry revealed severe hypoglycaemia, associated with low serum fructosamine and high insulin concentrations. On abdominal ultrasound, a focal hypoechoic well-defined mass in the left limb of the pancreas was identified and the presence of an additional smaller nodule was suspected. Contrast-enhanced ultrasonography (CEUS) confirmed the presence of both lesions and revealed a third, even smaller nodule. Partial pancreatectomy was performed. Histopathology and immunohistochemistry confirmed the presence of a multifocal insulinoma. Six months later, the cat presented with tenesmus and obstipation. A colorectal adenocarcinoma was diagnosed with histopathology after partial excision of a colorectal mass. The cat was euthanased a month later owing to recurrent episodes of severe obstipation.

Relevance and novel information

This is the first clinical description of the use of CEUS in the diagnosis of feline insulinoma. Furthermore, the available scientific literature on feline insulinoma was reviewed.

Insulinoma in Dogs: A Review

Insulinomas are rare malignant functional pancreatic tumors of the β cells that retain the ability to produce and secrete insulin. Insulinomas are the most common pancreatic neuroendocrine tumor in dogs that can induce a variety of clinical signs that result from hypoglycemia and secondary neuroglycopenic and adrenergic effects. Diagnosis and treatment is considered challenging, and the prognosis can be extremely variable depending on the therapeutic choices. This review aims to summarize and update classic knowledge with current trends in the diagnosis, treatment, and prognosis of insulinomas.

Hyperalbuminemia associated with hepatocellular carcinoma in a dog

A 12-year-old, neutered male, mixed-breed dog was presented to The Ohio State University Veterinary Teaching Hospital with a history of weight loss and weakness. Laboratory abnormalities reported by the referring veterinarian during the past year included increased alkaline phosphatase (ALP) activity, hyperalbuminemia, and nonregenerative anemia. On referral, the dog appeared hydrated and had moderate muscle wasting and hepatomegaly. A large lobular hepatic mass was observed ultrasonographically. Laboratory results included mild to moderate nonregenerative anemia, urine-specific gravity of 1.035, 3+ proteinuria, increased serum activities of alanine aminotransferase (229 U/L, reference interval 10-55 U/L), ALP (813 U/L, reference interval 15-120 U/L), and the steroid-induced isoform of ALP (676 U/L, reference interval 0-6 U/L), marked hyperalbuminemia (5.3 g/dL, reference interval 2.9-4.2 g/dL), and an increased A/G ratio (1.7). Hyperalbuminemia was confirmed by reanalysis on 2 different analyzers and by agarose gel electrophoresis, and colloid osmotic pressure (COP) was markedly increased (42.5 mmHg, reference interval 20-25 mmHg). Cytologic examination of a fine-needle aspirate of the hepatic mass indicated hepatocellular proliferation; histologic examination of an excisional biopsy confirmed hepatocellular carcinoma. Three weeks after surgery, the albumin concentration, A/G ratio, COP, and ALT activity had normalized, but ALP activities remained high. We hypothesized that hyperalbuminemia developed secondary to hepatocellular carcinoma due to increased synthesis of albumin by malignant hepatocytes or due to decreased negative feedback from impaired hepatocellular osmoreceptivity. Hepatocellular carcinoma has been associated with paraneoplastic secretion of other proteins, but hyperalbuminemia has been reported only once in a human patient and has not previously in dogs.

Insulinoma in a Dog With Pre-existing Insulin-Dependent Diabetes Mellitus

A 10-year-old golden retriever with a 3-year history of insulin-dependent diabetes mellitus was presented with recurring episodes of hypoglycemia and seizures. A presumptive diagnosis of an insulinoma was made based on hypoglycemia with concurrent endogenous hyperinsulinemia and unremarkable radiographic and ultrasonographic images of the chest and abdomen. A beta cell carcinoma of the pancreas with metastasis to the liver and a mesenteric lymph node was confirmed by surgery and histopathology.

Hypoglycemia and irreversible neurologic complications in a cat with insulinoma

A 14-year-old spayed female domestic shorthair cat was evaluated for weakness, lethargy, decreased appetite, diarrhea, weight loss, and seizures. On physical examination, the cat appeared disoriented and had an inconsistent menace response. An insulinoma was diagnosed on the basis of normal serum insulin activity in conjunction with profound hypoglycemia and histologic examination (with immunohistochemical staining for chromogranin A and insulin) of a pancreatic mass that was removed surgically. Blood glucose concentration was within reference limits after surgery. However, neurologic abnormalities persisted, and the cat was euthanatized. Chronic hypoglycemia, associated with insulinomas, can cause irreversible neuronal changes in cats; therefore, rapid diagnosis and treatment of hypoglycemic conditions are of critical importance.

Endocrine tumors

Because of the diverse nature of endocrine organs, and their vast range of physiologic functions, endocrine tumors encompass a wide range of origination sites and disease entities. The clinical picture of affected individuals is highly dependent on the tissue of origin, and the presence or absence of functional hormone secretions. Identification, localization, and therapeutic strategies, as well as prognosis can vary greatly. Many endocrine tumors have been described in human as well as veterinary patients. This article focuses on endocrine tumors of dogs and cats. Various tumors affecting the pancreas, thyroid, parathyroid, adrenal and pituitary glands are described, including insulinoma, gastrinoma, glucagonoma, and thyroid carcinoma, as well as parathyroid hormone- and growth hormone-secreting tumors. The syndrome of multiple endocrine neoplasia is also described.