Histopathological and Immunohistochemical Characteristics of Thyroid Carcinoma in the Dog.

Thyroid carcinomas are a common form of endocrine neoplasia in dogs. In the present study, we combined histopathology with immunohistochemistry (IHC) to search for the presence of oestrogen receptor alpha (ORα), Cox-2 and Ki67 in canine thyroid carcinomas. Forty-eight thyroid carcinomas were diagnosed throughout the study period. Thyroglobulin and calcitonin IHC distinguished between thyroid tumours with a follicular and medullary (C-cell) origin, respectively. IHC-based diagnosis showed that 42 (87.50%) of the cases were follicular cell carcinoma. In these cases, the follicular-compact pattern was the most frequent (n = 20/42; 47.62%) and six cases (12.5%) were medullary cell (C-cell) carcinomas. Both medullary (C-cell) and follicular carcinomas expressed Ki67 and Cox-2. No differences were observed between medullary and follicular carcinomas with respect to expression of Ki67 (P = 0.34) and Cox-2 (P = 0.9523) markers. A total of 4.17% (n = 2/48) of thyroid carcinomas showed positive nuclear labelling for ORα, suggesting that oestrogen does not directly participate in the pathogenesis of canine thyroid neoplasia.

Endocrine tumours in the guinea pig.

Functional endocrine tumours have long been thought to be rare in guinea pigs, although conditions such as hyperthyroidism and hyperadrenocorticism have been documented with increasing frequency so the prevalence of hormonal disorders may have been underestimated. Both the clinical signs and diagnosis of hyperthyroidism in guinea pigs appear to be very similar to those described in feline hyperthyroidism, and methimazole has been proven to be a practical therapy option. Hyperadrenocorticism has been confirmed in several guinea pigs with an adrenocorticotropic hormone stimulation test using saliva as a non-invasive sample matrix; trilostane has been successfully used to treat a guinea pig with hyperadrenocorticism. Insulinomas have only rarely been documented in guinea pigs and one animal was effectively treated with diazoxide.

Endocrine causes of calcium disorders.

Endocrine diseases that may cause hypercalcemia and hypocalcemia include hyperparathyroidism, hypoparathyroidism, thyroid disorders, hyperadrenocorticism, hypoadrenocorticism, and less commonly pheochromocytoma and multiple endocrine neoplasias. The differential diagnosis of hypercalcemia may include malignancy (lymphoma, anal sac carcinoma, and squamous cell carcinoma), hyperparathyroidism, vitamin D intoxication, chronic renal disease, hypoadrenocorticism, granulomatous disorders, osteolysis, or spurious causes. Hypocalcemia may be caused by puerperal tetany, pancreatitis, intestinal malabsorption, ethlyene glycol intoxication, acute renal failure, hypopararthyroidism, hypovitaminosis D, hypomagnesemia, and low albumin. This article focuses on the endocrine causes of calcium imbalance and provides diagnostic and therapeutic guidelines for identifying the cause of hypercalcemia and hypocalcemia in veterinary patients.

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.

Neoplastic and non-neoplastic lesions in the mammary gland, endocrine and genital organs in aging male and female Sprague-Dawley rats.

The non-neoplastic and neoplastic lesions in adrenals, thyroids, pituitary, uterus, ovaries, testes and mammary gland of senile untreated Sprague-Dawley rats were evaluated. The correlation between the neoplastic and non-neoplastic lesions in the pituitary gland and those in the target organs was made. The pituitary gland of the senile Sprague-Dawley rats had focal or diffuse hyperplasia and/or hypertrophy of PRL, STH, and ACTH cells. Approximately 47% of the males and 62% of the females had pituitary adenomas. Multiple adenomas in the same pituitary were noted in 7% of the males and in 11% of the females. Although many adenomas contained pleomorphic foci and quite a number of mitotic figures and were locally invasive, no evidence of distant metastases was discovered; therefore carcinoma was not diagnosed in the present material. The adenomas observed were divided into different types on the basis of the cytological characteristics of the cellular elements. Single cell-type adenomas such as PRL-, ACTH-, STH-, TSH-, immature- gonadotrophin-cell adenomas, and mixed cell (more than one cell type) adenomas were diagnosed. The adenomas containing PRL cells were the predominant type of neoplasms and they represented 30% and 34% of the total pituitary neoplastic lesions observed in males and females, respectively. The cytological changes in the hypophyseal cell types in senile Sprague-Dawley rats were usually accompanied by spontaneous non-neoplastic and neoplastic lesions in adrenals, thyroids, testes, ovaries, and mammary gland. The possible role of the hypophyseal hormones in the induction of the non-neoplastic and neoplastic lesions in the target organs is discussed. The combination of the spontaneous endocrine tumors could be associated both with aging and with genetic background of the animals. In addition, this polyglandular proliferative lesion in Sprague-Dawley rats might represent a potential model of mixed MEN syndrome.

Endocrine neoplasia in New World primates.

Of 1,106 New World primates necropsied from the National Zoological Park (Washington, D.C.) and the Department of Comparative Pathology, Johns Hopkins University School of Medicine (Baltimore, Maryland) 22 (1.9%) animals were identified with 27 neoplasms. Of this group, nine animals (two females, seven males) had a total of 13 endocrine neoplasms. All animals were adults, with an age range of 2.7-25 years (average, 12.1 years). Seven were Callitrichidae and two were Cebidae. The adrenal gland was the most affected organ, with seven (53.8%) neoplasms, followed by the pituitary and thyroid gland with two (15.4%) cases each, and the pancreas and parathyroid gland with one tumor (7.7%) each. All neoplastic disorders were benign. Immunocytochemistry assays for growth hormone, adrenocorticotropic hormone, prolactin, follicle-stimulating hormone, luteinizing hormone, thyroid-stimulating hormone, and chromogranin A were performed on two pituitary neoplasms. Pheochromocytoma was the most frequent neoplasm, representing 5 (38.4%) of the 13 neoplasms. The remaining were thyroid cystadenoma (two, 15.4%), corticotrophic cell pituitary adenoma (two, 15.4%), adrenal ganglioneuroma (one, 7.7%), adrenal cortical adenoma (one, 7.7%), parathyroid chief-cell adenoma (one, 7.7%), and pancreatic islet-cell adenoma (one, 7.7%).

Evaluation of endocrine function.

This article outlines strategies on how to approach equine endocrine disorders based on clinical signs and clinical pathologic data. In the 1987 Veterinary Clinics of North America: Equine Practice article on evaluating equine endocrine function, Beech stated that the numbers of hormonal assays available to use in horses was limited. Unfortunately, not much has changed since then. With the advent of convenient assay kits for many hormones and cofactors available in human medicine, it is possible to submit samples to laboratories for measurement of a wide range of endogenous substances. Caution must be used when interpreting the results in equine patients. Assay kits that have not been validated for use in horses may yield results that have no clinical meaning. Using veterinary endocrinology laboratories with equine experience is the best way to assure meaningful results from diagnostic testing (Table 1). If this is not possible, submitting age, breed, and sex-matched controls along with samples from the patient horse will provide some measure of a reference range. Normal values or reference ranges from species other than the horse cannot be used to interpret the results of equine samples.

Variations in prevalence of endocrine tumors among different colonies of rats? A retrospective study in the Hannover registry data base.

Illustrated by data derived from the endocrine system it could be demonstrated that at least the following requirements have to be fulfilled when using historical control data for the interpretation of animal studies: The main and basic requirement is the utilization of standardized diagnostic criteria and a systematized nomenclature for all data which should be compared. This includes the historical control data as well as histopathological diagnoses obtained from other animal studies. All findings stored in the REGISTRY are based on standardized criteria and this nomenclature was also applied for the more recent studies which were evaluated by pathologists of the member companies. Data from literature which are frequently used for comparison and interpretation cannot always fulfill this requirement due to the variation of diagnostic criteria used by different investigators. The second important requirement is an exact knowledge of study-related details. Some dependencies of the tumor rate on the sex, the strain, the breeder and the age were shown in a few examples. But other parameters, like diet, caging, bedding etc. may also influence the frequency of spontaneously occurring tumors and therefore have to be taken into account. In the REGISTRY such data from routine carcinogenicity and toxicity studies are available because all these studies are performed under GLP conditions and all parameters are carefully recorded. During the relatively short period of its activity, the REGISTRY has become not only source of historical laboratory data, but also it subserves as indispensable tool of quality control warranted by peer-review effects of panel meetings. An additional benefit will emanate from the data base in the near future: Exact knowledge of the magnitude of the influence of distinct parameters will enable the member companies to use the information for the design or optimization of new studies, as well as to extend the analysis and support the interpretation of observed results.