Canine thyroid carcinomas: A review with emphasis on comparing the compact subtype of follicular thyroid carcinomas and medullary thyroid carcinomas

Canine thyroid carcinomas are relatively common malignant endocrine neoplasms in dogs derived from either thyroid follicular cells (forming follicular thyroid carcinomas) or medullary cells (parafollicular, C-cells; forming medullary thyroid carcinomas). Older and recent clinical studies often fail to discriminate between compact cellular (solid) follicular thyroid carcinomas and medullary thyroid carcinomas, which may skew conclusions. The compact subtype of follicular thyroid carcinomas appears to be the least differentiated subtype of follicular thyroid carcinomas and needs to be differentiated from medullary thyroid carcinomas. This review includes information on the signalment, presentation, etiopathogenesis, classification, histologic and immunohistochemical diagnosis, clinical management, and biochemical and genetic derangements of canine follicular and medullary carcinomas, and their correlates with human medicine.

[Neuroendocrine carcinoma of the gallbladder as a rare cause for melena and hematemesis in dogs]

A 9-year-old male Malinois was presented for further workup of acute melena, hematemesis and chronic weight loss for a duration of one month. Clinically, the patient presented with a mildly reduced general condition. Blood tests revealed mild non-regenerative anemia as well as a mild elevation of alanine aminotransferase (ALT). Ultrasonography showed signs of an early mucocele. Treatment with gastroprotectants failed to lead to clinical improvement and the dog developed progressive anemia. Gastroduodenoscopy was unremarkable. Due to persistent clinical signs, exploratory laparotomy was performed. An ulcerated bleeding mass was detected at the gallbladder neck. Histopathological examination led to the diagnosis of a neuroendocrine carcinoma. There was no evidence of a mucocele on histopathology. Melena and hematemesis subsided postoperatively and 13 months after cholecystectomy, the dog remains without clinical signs. Neuroendocrine carcinomas of the gallbladder should be considered as a rare cause of melena and hematemesis in dogs.

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.

Perianal neuroendocrine tumor with suspected lymph node metastasis causing colonic compression and subsequent megacolon

An 8-year-old spayed female domestic shorthair cat was presented with a 4- to 5-month history of a progressively growing mass above her anus and an inability to defecate for 3 to 4 wk. External perianal and internal regional masses were subsequently identified and diagnosed as tumors of neuroendocrine origin through surgical excision and histopathologic evaluation. The cat was treated with 2 courses of chemotherapy and radiation therapy.

Neuroendocrine carcinoma in the nasal cavity of ten dogs

Neuroendocrine (NE) carcinoma was diagnosed in 10 dogs. In six cases examined by cephalometric radiography and computerized tomography, a large mass was seen to fill the nasal cavity. Histopathologically, sheets, nests or ribbons of neoplastic cells were separated by delicate or thick fibrovascular stroma. The neoplastic cells were round, oval, or spindle-shaped; cytoplasmic granules and hyperchromatic nuclei with prominent nucleoli were present. Neoplastic cells were invariably immunohistochemically positive for cytokeratin (CK) AE1/AE3, neuron-specific enolase, chromogranin A and vasoactive intestinal polypeptide. Eight dogs were positive for S100 protein, seven for synaptophysin, five for protein gene product 9.5, two for somatostatin, and one for Leu-7. Immunolabelling gave negative results for CK 8, CK 19, calcitonin, calcitonin gene-related polypeptide, neurofilaments, serotonin, gastrin and glial fibrillary acidic protein. Ultrastructurally, the neoplastic cells contained a large number of round, membrane-bounded, densely-cored granules corresponding to neurosecretory granules. These observations were consistent with the neuroendocrine nature of the carcinomas.

Hepatobiliary neuroendocrine carcinoma in cats: a clinicopathologic, immunohistochemical, and ultrastructural study of 17 cases

Hepatobiliary neuroendocrine carcinoma was diagnosed in 17 cats in a period of 10 years. Seven tumors were of intrahepatic origin, one of which was a composite containing components of epithelial and neuroendocrine carcinoma. Nine tumors were of extrahepatic origin, and one tumor was located in the gall-bladder. The cats were adult and geriatric, and the male : female ratio varied according to tumor group. Hepatomegaly, anorexia, weight loss, and vomiting were the most common clinical signs observed in the cats with hepatic neuroendocrine carcinoma. The cats with extrahepatic neuroendocrine carcinoma showed these signs plus icterus (5/9) and high concentrations of hepatic enzymes. Histologically, the hepatic neuroendocrine carcinomas had two patterns, one with acinar structures separated by vascular stroma lined by cuboidal or columnar cells and the other solid with groups of anaplastic cells separated by vascular stroma. The composite tumor consisted of both bile duct carcinoma and neuroendocrine carcinoma. The extrahepatic neuroendocrine carcinomas and the gallbladder neuroendocrine carcinoma were characterized by solid sheets or groups of round to oval cells with vascular or fibrovascular stroma. Immunohistochemical examination of 10 of the neuroendocrine carcinomas revealed that all 10 stained with neuron-specific enolase; one bile duct carcinoma and the gallbladder carcinoma stained with chromogranin; four of five bile duct carcinomas and the gall bladder carcinoma stained with synaptophysin; and one bile duct carcinoma stained with gastrin. One cat with hepatic carcinoma had duodenal ulcer; in this cat, ultrastructural studies showed neurosecretory granules leading to the diagnosis of Zollinger-Ellison syndrome. In four cats in which necropsy was permitted, carcinomatosis (4/4), lymph nodes (4/4), lungs (2/4), and intestines (1/4) were the metastatic sites. Fourteen of the 17 cats were euthanatized during or immediately after surgery.

Canine hepatic neuroendocrine carcinoma: an immunohistochemical and electron microscopic study

Ten dogs with neuroendocrine carcinoma of the liver were selected for inclusion in the study. Clinical signs were anorexia (7), vomiting (5), polydipsia/polyuria (3), icterus (2), lethargy (2), weight loss (2), paresis (1), ataxia (1), weakness (1), collapse (1), and urinary tract infection (1). Hematologic and biochemical abnormalities included anemia (2/8), leukocytosis (4/8), high liver enzyme activity (serum alkaline phosphatase, 7/9; alanine transaminase, 7/9; aspartate transaminase, 8/9), and high total bilirubin (6/9). Grossly, the tumors were diffuse, involving all liver lobes in six dogs, and two dogs had various-sized nodules in addition to diffuse involvement. Histologically, there were eight tumors with solid or trabecular pattern (group A), one tumor with cords or rows of neoplastic cells (group B), and one tumor with multiple rosette-like structures (group C). Immunohistochemical studies revealed that all 10 neoplasms were positive for at least one of the endocrine markers used: neuron-specific enolase (NSE; 8/10), synaptophysin (5/10), and chromogranin-A (3/10). A panel of NSE, chromagranin-A, and synaptophysin detected 100% of the tumors in our series. Electron microscopy confirmed the diagnosis by the presence of intracytoplasmic neurosecretory granules in the two examined cases. Our results show that neuroendocrine markers commonly used in humans can be used for the diagnosis of hepatic neuroendocrine carcinoma in dogs, preferably a panel of synaptophysin, chromagranin-A, and NSE because chromogranin-A alone is not as useful in dogs as in humans.

Neuroendocrine carcinoma of the nasopharynx in a dog

Neuroendocrine carcinoma of the nasopharynx was diagnosed in a 9-year-old male Golden Retriever. The mass was identified by computed tomography of the nasal cavity and nasopharyngoscopy, and it was surgically excised. Histologic, cytochemical, and electromicroscopic examination of specimens confirmed the type of tumor. The dog was clincally improved for 150 days but was then reexamined because of respiratory difficulty and poor appetite. Thoracic radiographs revealed multiple nodules in all lung lobes, and ultrasonography revealed a mass in the spleen. The dog died the next day.

Hepatic carcinoid, hypercortisolism and hypokalaemia in a dog

A German Shepherd dog was diagnosed with periodic myopathy secondary to persistent hypokalaemia. Hormone analysis revealed excess cortisol secretion. A neuroendocrine carcinoma, thought to be a primary hepatic carcinoid, was detected in the liver. Ectopic adrenocorticotrophin hormone secretion was suspected as the cause of hypercortisolism and hypokalaemia, although this could not be confirmed by immunohistochemical staining.

Thymic carcinoma with neuroendocrine differentiation in a calf

A neuroendocrine carcinoma originating in the thymus was found in a 7-month-old, castrated male, Japanese Black calf. The neoplasm consisted largely of very primitive cells, characterized by the paucity of cytoplasmic organelles, but a few cells were immunoreactive for somatostatin or neurofilaments. The expression of both cytokeratin and neurofilament protein was a feature of neuroendocrine differentiation. This neoplasm considered to be a tumor of a thymic stem cell, with little but indubitable evidence of differentiation into somatostatin-producing cells.

Hepatic carcinoma with spleen metastasis in a California sea lion from the Gulf of California

A primary hepatic carcinoma with a neuroendocrine pattern was detected in an adult female California sea lion (Zalophus californianus) found dead on Granito Island in the Gulf of California (Mexico) in January 1996. At necropsy, several light yellow nodules of different sizes were observed on the entire surface of the liver and spleen. Microscopic examination of these nodules using routine haematoxylin-eosin stain, revealed cubic, polyhedral and pleomorphic cells with three to four bizarre mitotic figures per field (40X). An immunohistochemistry test revealed a positive reaction of indirect immunoperoxide to cytokeratin (CK2). This is the first known case of a primary hepatic carcinoma in free-ranging California sea lions from Mexican waters.

Pancreatic endocrine carcinoma with multiple hormone production in a raccoon (Procyon lotor)

A pancreatic endocrine carcinoma with lung metastases was found in a 15-year-old male raccoon. This tumour was characterized by great variation in cell size and production of multiple polypeptide hormones. Endocrine markers expressed by the neoplastic cells were, in descending order of frequency, chromogranin A, pancreatic polypeptide (PP), glucagon, somatostatin and insulin. Co-expression of PP and glucagon, somatostatin or insulin was demonstrated immunohistochemically with consecutive sections, and cells with both glucagon and insulin were also observed. The pattern of co-expression was similar to that in the earliest stages of murine pancreatic development. Amyloid deposits in the islets of Langerhans, which reacted with antibody to islet amyloid polypeptide, were thought to be associated with age.

Pulmonary neuroendocrine carcinoma in a four-month-old dog

A 4-month-old male Siberian Husky dog had a history of coughing, high fever and anorexia. Thoracic radiographs revealed increased radiographic density in the cranial and middle lobes of the right lung, with pleural effusion. Cytological examination of the pleural fluid suggested carcinomatous pleuritis. Right-side thoracotomy and resection of the cranial and middle lobes were performed. Histopathological examination of the resected tissue revealed an anaplastic large cell carcinoma. The tumour cells were positive for neuron specific enolase and also contained neuroendocrine granules. A particularly unusual feature of this case of pulmonary neuroendocrine carcinoma was the young age of the affected animal.