An atypical case of recurrent carotid body carcinoma in a young adult dog: Histopathological, immunohistochemical and electron microscopic study.

A 3.5-year-old female Chihuahua was presented with complaint of neck pain, intermittent cough and dysphagia. Physical examination and diagnostic imaging of neck region revealed a solid and highly vascularized mass involving the retropharyngeal region. Histologically, the mass showed an atypical zellballen pattern which comprised of high density of type I chief cells with high nuclear cytoplasmic ratio and separated by delicate fibrovascular stroma. Immunoreactivity for neuroendocrine markers was diffusely positive in cytoplasm of tumor cells. Disseminated tumor emboli in external jugular vein were detected 6 months after initial surgery. An electron microscopic study revealed numerous electron-dense intracytoplasmic neurosecretory granules. Based on these findings, carotid body carcinoma was diagnosed.

CT AND MRI FEATURES OF CAROTID BODY PARAGANGLIOMAS IN 16 DOGS.

Carotid body tumors (paragangliomas) arise from chemoreceptors located at the carotid bifurcation. In imaging studies, this neoplasm may be confused with other neck neoplasms such as thyroid carcinoma. The purpose of this retrospective, cross-sectional study was to describe computed tomographic (CT) and magnetic resonance imaging (MRI) characteristics of confirmed carotid body tumors in a multi-institutional sample of dogs. A total of 16 dogs met inclusion criteria (14 examined using CT and two with MRI). The most common reason for imaging was a palpable cervical mass or respiratory signs (i.e., dyspnea or increased respiratory noises). The most commonly affected breed was Boston terrier (n = 5). Dogs were predominantly male castrated (n = 10) and the median age was 9 years [range 3-14.5]. Most tumors appeared as a large mass centered at the carotid bifurcation, with poor margination in six dogs and discrete margins in ten dogs. Masses were iso- to hypoattenuating to adjacent muscles in CT images and hyperintense to muscles in T1- and T2-weighted MRI. For both CT and MRI, masses typically showed strong and heterogeneous contrast enhancement. There was invasion into the adjacent structures in 9/16 dogs. In six of these nine dogs, the basilar portion of the skull was affected. The external carotid artery was entrapped in seven dogs. There was invasion into the internal jugular vein in three dogs, and into the external jugular, maxillary, and linguo-facial veins in one dog. Imaging characteristics helped explain some clinical presentations such as breathing difficulties, Horner's syndrome, head tilt, or facial nerve paralysis.

Cytological, histological and ultrastructural nuclear features of monster cells in a canine carotid body carcinoma.

A 7-year-old female Shih-tzu dog was presented with severe dyspnoea. A large mass was palpated in the left cranial neck. Cytological examination of an aspirate sample revealed cells with marked anisokaryosis, giant elements and many bare nuclei. Scattered intact giant cells showed scant, granular cytoplasm and intranuclear inclusions. Histologically, neoplastic cells were subdivided into lobules by fine collagenous trabeculae. Numerous pleomorphic giant, or 'monster', cells were observed, showing a highly indented nuclear envelope, intranuclear cytoplasmic pseudoinclusions (ICPs) and 'ground-glass' nuclear appearance. Neoplastic emboli were present, but no distant metastases were detected grossly. Immunohistochemically, the neoplastic cells expressed synaptophysin and had variable expression of neuron-specific enolase and vimentin. The cells were negative for pan-cytokeratin, CAM 5.2, glial fibrillary acidic protein and S100. Nuclear abnormalities and cytoplasmic neurosecretory granules were noted ultrastructurally. These features were consistent with a diagnosis of carotid body carcinoma (chemodectoma). Monster cells with ICPs have not been documented previously in canine chemodectoma.

Syncope associated with swallowing in two British Bulldogs with unilateral carotid body tumours.

Carotid body tumours were diagnosed in two British Bulldogs that each had a history of syncopal episodes induced by eating, drinking or pulling on the leash. In both dogs, a cervical mass was identified using computed tomography (CT) or magnetic resonance imaging, with carotid body tumour (CBT) being the histopathological diagnosis. A heart base mass was also identified in one dog by both CT and echocardiography. Swallowing syncope has been reported in the human literature in association with cervical mass lesions, but this is the first report in dogs. The present cases emphasise the value of advanced imaging of the head and neck in dogs presenting with clinical signs of syncope associated with swallowing and the importance of careful manipulation of the neck in patients with CBTs.

Comparison between clinical, ultrasound, CT, MRI, and pathology findings in dogs presented for suspected thyroid carcinoma.

This study compares clinical, ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), and pathology findings in 16 prospectively, and seven retrospectively recruited dogs presented for suspected thyroid carcinoma. Of these, 17 were confirmed thyroid carcinoma, while six were initially misdiagnosed. These included four carotid body tumors, one para-esophageal abscess, and one undifferentiated squamous cell carcinoma. Thyroid carcinomas occurred in older dogs without evidence of sex predilection, and were more often unilateral. All were large, heterogeneous, moderately to strongly vascularized, and most commonly contained areas of dystrophic mineralization and/or fluid accumulations. On MRI, thyroid carcinomas appeared hyperintense compared to surrounding musculature in all imaging sequences used, while on CT they had a lower attenuation value than normal thyroid gland tissue. Histologically confirmed tumor capsule disruption with invasion of the surrounding structures was most commonly detected with MRI. Palpation was not an accurate predictor of locally invasive vs. well-encapsulated masses. Computed tomography had the highest specificity (100%) and MRI had the highest sensitivity (93%) in diagnosing thyroid carcinoma, while ultrasound had considerably lower results. We conclude that ultrasound is adequate for use as a screening tool for dogs with suspected thyroid carcinoma, but recommend either CT or MRI for preoperative diagnosis and staging.

Magnetic resonance and computed tomography imaging of a carotid body tumor in a dog.

A 5-year-old castrated male Labrador Retriever was presented to a referring veterinarian for a swelling in the neck region. Based on the results of histopathology, a carotid body tumor, was diagnosed. The dog was referred to a medical imaging unit for further staging and follow up. This report describes the magnetic resonance (MR) and computed tomographic (CT) appearance of a carotid body tumor.

Multiple osseous metastases of a carotid body tumor in a dog.

Metastasis of malignant carotid body tumor to multiple bones was detected in a 13-year-old female Siberian husky dog. Radiographs exhibited an abnormal mass in the retropharyngeal site and osteolytic lesions in the vertebral bodies, spinous process, tibia, and ribs. At necropsy, multiple masses were observed in the bones as well as at the dorsal area of the retropharynx. Histologically, the tumor cells, arranged in sheets and clusters, had eosinophilic finely granular cytoplasm. Immunohistochemistry showed the tumor cells were positive for neuron-specific enolase and synaptophysin. Electron microscopy demonstrated a number of dense membrane-bound granules in the cytoplasm of the tumor cells. Based on these findings, this case was diagnosed as multiple bone metastases of a malignant carotid body tumor. Spinal cord damage induced by the tumor mass was the cause of the hind limb paralysis of the present dog.

Immunohistochemical characteristics of canine aortic and carotid body tumours.

In an immunohistochemical study of 25 canine chemodectomas, 17 tumours were stained with antisera to neurone specific enolase and the same number were stained for synaptophysin; a single tumour was stained for S100. Staining for Ki-67 occurred in 18 cases; the Ki-67-labelling index and the intensity of immunostaining was increased in more pleomorphic and malignant tumours, as assessed on histological grounds. Immunohistochemistry did not aid in recognition of less well-differentiated tumours.

Metastatic intracavitary cardiac aortic body tumor in a dog.

A mobile right-ventricular mass dynamically occluding the right ostium atrioventriculare in the systolic phase was detected in a 3-year-old male Tosa dog by echocardiography. At necropsy, multiple tumor masses of various sizes were observed in the heart base right ventricular lumen, myocardium, lung and liver. Dysplasia of tricuspid valve characterized by irregular shape of leaflets, upward malposition of large papillary muscles, and shortened and stout chordae tendineae was also detected. Histopathologically, the tumor cells, arranged in sheets or nests, were polyhedral with lightly eosinophilic and finely granular cytoplasm, and contained a hyperchromatic round or oval nucleus. By Grimelius' silver stain, tumor cells had cytoplasmic positive granules. Ultrastructurally, tumor cells contained characteristic small membrane-limited granules. This is the first report of metastatic intracavitary cardiac aortic body tumor in a dog.

Carotid body tumors in the dog. Eleven cases (1978-1988).

Case records of 11 dogs with histologically confirmed carotid body tumors were reviewed. Surgical excision had been attempted in ten dogs with carotid body tumors, and one dog had been euthanatized at diagnosis. There were no intraoperative deaths but perioperative mortality was 40%. Horner's syndrome and laryngeal paralysis were the most common postoperative morbidities. The median survival time after surgery alone in the four dogs that survived the perioperative period was 25.5 months (range, 12-45 months). Two dogs treated with postoperative radiation therapy had survival times of 6 and 27 months. Of the six dogs surviving the perioperative period, two dogs are still alive at 19 and 32 months postoperatively. Of the four dogs that died, one was euthanatized 12 months postoperatively for nontumor-related causes. The remaining three dogs died of distant metastases. The carotid body tumors studied were characterized by local tissue invasion, neurovascular complications after therapy, and a propensity to metastasize to multiple sites in the body.

Carotid body tumor: an incidental finding in older ranch mink.

Carotid body tumors were found incidentally at necropsy in 15 ranch mink (Mustela vision), mostly royal pastels, kept for studies on slow viral diseases. The mink, five males and ten females, were 77 to 135 months old (mean age 107 months). Loosely or firmly attached at the bifurcation of the common carotid artery, and 11 larger tumors were smooth-surfaced, discrete, pale brown, globoid masses that varied from 2.5 to 16 mm in diameter. Four tumors of microscopic size occurred in otherwise normal-looking carotid bodies. All were composed of densely packed polygonal cells disposed in sheets and cords or arranged in clusters by a reticulin meshwork rich in blood vessels. Always unilateral, the tumors had not invaded locally or metastasized. As seen in the smallest tumors, the neoplastic cells usually arose centrally in the carotid body and formed an expansive growth that replaced much of the normal parenchyma without necessarily enlarging the organ beyond normal limits. The cause of the tumors was not apparent. All tumor-bearing mink had lived at an elevation of 1,100 meters, and none had suffered from any obvious chronic cardiopulmonary disease.

Electromyography in the localization of spinal cord and nerve root neoplasia in dogs and cats.

In 8 cases (6 dogs and 2 cats) of spinal cord and nerve root neoplasia, electromyography was used to localize the area of involvement. The locations of the lesions were confirmed at necropsy.

Carotid body tumors in the dog: a review and report of four cases.

Of 3,837 canine neoplasms from case records at Kansas State University, only 4 were of carotid body tumors. Information on these 4 cases, added to that on 18 cases already reported, indicated that such tumors are found most frequently in old dogs, principally in brachycephalic breeds. Although predisposition toward the male sex has been suggested for tumors of the chemoreceptor system, none was observed for carotid body tumors. Multicentricity apparently is not uncommon for chemoreceptor tumors; 9 of the 22 dogs simultaneously had aortic body tumor.