Endocrine tumors

Nuclear Imaging and Radiation Therapy in Canine and Feline Thyroid Disease

The indications, techniques, and expectations for radionuclide diagnostic studies on canine and feline thyroid glands are presented. In addition, the considerations surrounding radioiodine or external beam radiotherapy for benign and malignant thyroid disease are reviewed. The intent of this article is to familiarize primary care veterinarians with the utility of and outcome of the ionizing radiation-based diagnostic and therapeutic techniques for assessing and treating canine and feline thyroid disease.

A comparison of medullary thyroid carcinoma and thyroid adenocarcinoma in dogs: a retrospective study of 38 cases

The medical records of 38 dogs with thyroid neoplasia that were treated by surgical excision of the tumor, or had an incisional biopsy performed as a diagnostic procedure, were reviewed. Of the 38 dogs, 21 (55%) had resectable tumors, whereas 17 (45%) had an incisional biopsy as the tumors were nonresectable. All dogs had an initial diagnosis of thyroid carcinoma. The type of carcinoma was confirmed in 33 dogs by histological and immunohistochemical examination. Twelve dogs (36%) had medullary thyroid carcinoma, and 21 dogs (64%) had thyroid adenocarcinoma. Of the 12 dogs with medullary thyroid carcinoma, 10 (83%) had resectable tumors. Of the 10, three (30%) had at least a 1-year survival. None had radiographic evidence of metastasis at the time of surgery. Of the 21 dogs with thyroid adenocarcinoma, 11 (52%) had resectable tumors. Of the 11 dogs, five (45%) had at least a 1-year survival. Three dogs had radiographic evidence of metastasis at the time of surgery. Of 10 dogs with nonresectable thyroid adenocarcinoma, two dogs (20%) had at least a 1-year survival. In the dogs in this study, medullary thyroid carcinoma was more prevalent than previously reported. Most of the medullary thyroid carcinomas were well circumscribed and resectable. Medullary thyroid carcinoma may possess gross and histological characteristics of a less malignant nature when compared with other thyroid carcinomas.

Neoplastic diseases of the thorax

Thoracic neoplasia comprises a heterogeneous group of diseases, many of which are distinctly uncommon in veterinary medicine. These diseases often present the clinician with diagnostic and therapeutic challenges. Careful diagnostic work-up and staging are essential for consideration of therapeutic options and formulation of prognosis. Neoplastic diseases of the thorax are classified here as tracheal tumors, primary lung tumors, nonrespiratory intrathoracic tumors, and thoracic wall tumors.

Immunocytochemistry of normal pancreatic islets and spontaneous islet cell tumors in dogs

Immunocytochemical studies of the distribution of glucagon, gastrin, insulin, and somatostatin in normal canine pancreatic islets and 20 canine islet cell tumors were done using the peroxidase-anti-peroxidase (PAP) technique. In the normal adult canine pancreas, islets typically consisted of clusters of 20-30 cells, but smaller foci and even individual cells were identified. Alpha cells (glucagon) were often peripherally located, beta cells (insulin) were centrally located and most numerous, and delta cells (somatostatin) were the least numerous and randomly located. Both juvenile and adult canine pancreases did not stain for gastrin. Of the 20 tumors examined, 18 had positive immunoreactivity for insulin, nine for glucagon, 14 for somatostatin, and one for gastrin. Two tumors were uninterpretable due to autolysis. Three tumors were pure insulinomas, but no pure somatostatinomas, glucagonomas, or gastrinomas were identified. Most tumors and metastases had mixed positive immunoreactivity; one neoplastic cell type predominated with lesser numbers of other cell types. Metastatic sites (liver and lymph node) stained for insulin and somatostatin, only. Foci of non-neoplastic islet cell tissue (nesidioblastosis), often located at the pancreatic-mesenteric junction, stained strongly positive for insulin, glucagon, and somatostatin but not for gastrin. The tumor staining pattern did not consistently correlate with tumor function, as determined by blood glucose and serum insulin assays. The PAP technique works well on paraffin-embedded, formalin-fixed tissue using rabbit or guinea pig antisera as the primary antibody. Staining occurred on sections of paraffin blocks stored for up to 7 years.