Chemoreceptor neoplasia: a study of the epidemiological features of 357 canine cases

Ultrasound-Guided Radiofrequency Ablation of Chemodectomas in Five Dogs

Chemodectomas are low prevalence tumors with complex clinical management. Many present as an incidental finding however, in other dogs, they produce pericardial effusion and/or compression, leading to the appearance of severe clinical signs. There are currently several approaches: surgery, radiotherapy, stent placement and chemotherapy. This is the first description of percutaneous echo-guided radiofrequency ablation of aortic body tumors. This minimally invasive treatment is based on high frequency alternating electrical currents from an electrode that produces ionic agitation and generates frictional heat, causing coagulation necrosis. Five dogs with an echocardiographic and cytological diagnosis of chemodectoma underwent percutaneous echo-guided radiofrequency ablation. At the time of presentation, all the dogs showed clinical signs, such as ascites and/or collapse. There were no complications either during the procedure or in the following 24 hours. Rapid clinical improvement associated with a reduction in size and change in sonographic appearance of the mass were achieved with no complications. Six months follow-up was carried out in all dogs. A second percutaneous echo-guided RFA was performed eight months after the first procedure in one dog. Based on our experience, radiofrequency ablation seems to be a feasible and safe technique, making it a potential alternative therapeutic approach in the clinical management of aortic body tumors leading to severe clinical compromise.

Choroidal neuroendocrine neoplasia in a dog

OBJECTIVE

To report onset and progression of clinical signs of a neuroendocrine neoplasm (NEN) presumed metastatic to the choroid in a dog.

ANIMALS STUDIED

A 7.5-year-old female spayed German shepherd dog mix referred for advanced imaging and evaluation of a subretinal mass in the right eye.

PROCEDURES

Procedures performed included general physical and ophthalmic examinations; ocular, orbital, and abdominal ultrasonography; thoracic radiographs; cranial magnetic resonance imaging; serologic testing for infectious agents; analysis of hematologic as well as serum and urine biochemical parameters; echocardiography; electrocardiography; cytologic assessment of lymph nodes; and histopathology and immunohistochemistry of the enucleated globe.

RESULTS

Examination and imaging identified a pigmented mass within and expanding the superior choroid. Following enucleation, a choroidal NEN with tumor emboli in scleral blood vessels was diagnosed by histopathologic assessment and confirmed by immunohistochemical labelling. Despite extensive and repeated diagnostic testing over many months, a putative primary site was not identified until 19 months after the initial ocular signs were noted. At that time, a heart-base mass and congestive heart failure were highly suggestive of a chemodectoma.

CONCLUSION

This comprehensive report of a NEN presumed metastatic to the choroid in a dog suggests that ocular disease can be a very early and solitary sign of NEN in the dog.

A retrospective analysis of stereotactic body radiation therapy for canine heart base tumors: 26 cases

INTRODUCTION

This study retrospectively evaluated outcomes and adverse radiation effects (AREs) associated with stereotactic body radiation therapy (SBRT) for canine heart base tumors (HBTs). A secondary aim was to identify any demographic or echocardiographic factors that might determine which dogs would most benefit from SBRT.

ANIMALS

Twenty-six dogs that received SBRT for an imaging-based diagnosis of a HBT were evaluated.

METHODS

Twenty-three dogs were treated with three fractions of 10 Gy delivered daily or every other day. The remaining 3 dogs received variable protocols of one to five fractions. Demographic, echocardiographic, and radiographic information, AREs, and treatment responses were collected. Correlations of these data with survival time were evaluated.

RESULTS

The median overall survival time was 404 days (95% confidence interval: 239-554 days). The majority of dogs experienced a partial response (25%) or stable disease (60%) for a median duration of 333 days (95% confidence interval: 94-526 days). Three dogs had progressive disease within six months of SBRT. Radiographic pneumonitis was identified in 7 of 23 dogs, and clinical pneumonitis was identified in 4 dogs. No other AREs were noted. The rate of distant metastasis was 13%. On multivariate analysis, it was found that vena caval obstruction, supraventricular and ventricular arrhythmias, clinical signs, and enlarged locoregional lymph nodes at presentation were negatively associated with survival time.

CONCLUSIONS

Stereotactic body radiation therapy was delivered with a low rate and degree of normal tissue complications. Asymptomatic dogs with confirmed, progressive growth of a HBT may most likely benefit from SBRT.

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.

Pathologic and Immunohistochemical Findings in a Feline Aortic Body Tumor

The presence of a heart-base tumor was diagnosed by ultrasound imaging in a 10-year-old, female, domestic shorthaired cat presenting with dyspnea and pleural effusion because of the presence of a modified transudate. Hematology and clinical chemistry were unremarkable. The owner elected euthanasia. At necropsy, a locally extensive, firm, multilobulated nodule surrounded the pulmonary vein. The tumor was composed of lobules of large polygonal cells separated by a fine fibrovascular stroma. Tumor cells infiltrated the myocardium, and neoplastic emboli were present, but no metastases were macroscopically detectable. Tumor cells were immunohistochemically positive for chromogranin A, for synaptophysin and, faintly, for neuron-specific enolase and negative for vimentin, cytokeratin, a smooth muscle actin, glial fibrillary acidic protein, thyreoglobulin, and calcitonin. Based on histologic and immunohistochemical findings, the diagnosis of chemodectoma was made.

A descriptive review of cardiac tumours in dogs and cats

Cardiac tumours are uncommon in the canine and feline population and often an incidental finding. Common types include haemangiosarcoma (HSA), aortic body tumours (chemodectoma and paraganglioma) and lymphoma. These neoplasms can cause mild to severe, life-threatening clinical signs that are independent of the histological type and may be related to altered cardiovascular function or local haemorrhage/effusion into the pericardial space. Cardiac tumours may require symptomatic treatment aimed at controlling tumour bleeding and potential arrhythmias, and other signs caused by the mass effect. Additional treatment options include surgery, chemotherapy and radiotherapy. For all medical therapies, complete remission is unlikely and medical management, beyond adjunctive chemotherapy in HSA, requires further investigation but combination chemotherapy is recommended for lymphoma. The aim of this report is to summarize and critically appraise the current literature in a descriptive review. However, interpretation is limited by the lack of definitive diagnosis and retrospective nature of most studies.

Succinate dehydrogenase subunit D and succinate dehydrogenase subunit B mutation analysis in canine phaeochromocytoma and paraganglioma

Phaeochromocytomas (PCs) are tumours of the adrenal medulla chromaffin cells. Paragangliomas (PGLs) arise in sympathetic ganglia (previously called extra-adrenal PCs) or in non-chromaffin parasympathetic ganglia cells that are usually non-secretory. Parenchymal cells from these tumours have a common embryological origin from neural crest ectoderm. Several case series of canine PCs and PGLs have been published and a link between the increased incidence of chemoreceptor neoplasia in brachycephalic dog breeds and chronic hypoxia has been postulated. A similar link to hypoxia in man led to the identification of germline heterozygous mutations in the gene encoding succinate dehydrogenase subunit D (SDHD) and subsequently SDHA, SDHB and SDHC in similar tumours. We investigated canine PCs (n = 6) and PGLs (n = 2) for SDHD and SDHB mutations and in one PGL found a somatic SDHD mutation c.365A>G (p.Lys122Arg) in exon 4, which was not present in normal tissue from this brachycephalic dog. Two PCs were heterozygous for both c.365A>G (p.Lys122Arg) mutation and an exon 3 silent variant c.291G>A. We also identified the heterozygous SDHB exon 2 mutation c.113G>A (p.Arg38Gln) in a PC. These results illustrate that genetic mutations may underlie tumourigenesis in canine PCs and PGLs. The spontaneous nature of these canine diseases and possible association of PGLs with hypoxia in brachycephalic breeds may make them an attractive model for studying the corresponding human tumours.

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.

Histopathological and immunohistochemical evaluation of malignant potential in canine aortic body tumours

In order to verify the malignant potential of aortic body tumours (ABTs) in dogs, 13 cases of canine ABT were studied histopathologically and immunohistochemically. The cases were divided into two groups according to the presence or absence of metastases to other organs at necropsy examination (metastasis group [n = 9] and non-metastasis group [n = 4]). The mean tumour weight:body weight ratio (TW:BW; g/kg) in the metastasis group (9.3 ± 6.7) was significantly higher than that in the non-metastasis group (1.5 ± 1.7) (P <0.05). In both groups, the neoplastic cells had malignant features including pleomorphism, anisocytosis and anisokaryosis, and mononuclear giant cells were present, showing invasion through the capsule and into the vascular lumen and other adjacent tissues. The mitotic index (MI), mean nuclear area (NA) for size value and coefficient of variation of the nuclear area (CVNA) for anisonucleosis did not differ significantly between the two groups. These findings show that anaplastic characteristics are present regardless of the tumour size or the presence or absence of metastases, suggesting that these tumours are generally malignant or potentially malignant. Immunohistochemical analysis using neuroendocrine markers including neuron-specific enolase, chromogranin A and S100 revealed no obvious differences in labelling intensity of neoplastic cells related to the presence or absence of metastases or associated with the mean TW:BW, MI, NA or CVNA value, indicating that immunohistochemistry has no practical value for determining the tumour grade of canine ABTs.

Breed-predispositions to cancer in pedigree dogs

Cancer is a common problem in dogs and although all breeds of dog and crossbred dogs may be affected, it is notable that some breeds of pedigree dogs appear to be at increased risk of certain types of cancer suggesting underlying genetic predisposition to cancer susceptibility. Although the aetiology of most cancers is likely to be multifactorial, the limited genetic diversity seen in purebred dogs facilitates genetic linkage or association studies on relatively small populations as compared to humans, and by using newly developed resources, genome-wide association studies in dog breeds are proving to be a powerful tool for unravelling complex disorders. This paper will review the literature on canine breed susceptibility to histiocytic sarcoma, osteosarcoma, haemangiosarcoma, mast cell tumours, lymphoma, melanoma, and mammary tumours including the recent advances in knowledge through molecular genetic, cytogenetic, and genome wide association studies.

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.

A case of synchronous hepatocellular carcinoma and aortic body chemodectoma in a dog - pathological case report

The authors describe a case of synchronously occurring (double) tumours, i.e. primary hepatocellular carcinoma and aortic body chemodectoma in a 14-year-old mixed-breed male dog. The tumours were identified during necropsy, following euthanasia. In the last months of its life, the dog showed signs of weakness, anorexia, apathy, inactivity, and abdominal palpation elicited a painful reaction. The primary liver cancer emerged in the left lateral lobe without evidence of any distant metastases. Histopathological and immunohistochemical investigations revealed a well-differentiated, trabecular, claudin-7-, claudin-5- and pancytokeratin-negative hepatocellular carcinoma. The Ki-67 proliferation index was 33%. During necropsy, a synchronously occurring benign, grade I type aortic body chemodectoma was also detected in the dog. This neuroendocrine tumour showed chromogranin-, synaptophysin-, neuron-specific enolase- and S100 protein-positivity, and the Ki-67 proliferation index was 2%. The authors believe that this is the first description of synchronously occurring hepatocellular carcinoma and aortic body chemodectoma in a dog.

Aortic Body Tumor in Full-Sibling English Bulldogs

A 10-year-old, neutered male English bulldog died acutely from respiratory distress after a short history of progressive dyspnea. Less than 2 months later, a spayed female full sibling of that dog died suddenly during a nail trim. An aortic body tumor was the cause of death in both dogs based on postmortem and histological examinations. A pheochromocytoma was also diagnosed in the neutered male. Neither dog had a history of brachycephalic airway syndrome, and the implication for a genetic predisposition toward the development of paraganglioma is discussed. This is the first case report of aortic body tumors in sibling dogs, although the condition may not be an uncommon phenomenon.

Simultaneous aortic body tumor and pulmonary histiocytic sarcoma in a flat-coated retriever

A case of multiple primary tumors observed in the heart base and in the lung of a 7-year-old intact female, flat-coated retriever was reported. Morphological differences between both tumors and detailed immunohistochemical study revealed that the cardiac neoplasm was as a malignant aortic body tumor and the lung tumor was a pulmonary histiocytic sarcoma. The occurrence of aortic body tumor with other primary neoplasms has been previously reported in animals suggesting that this might be a common presentation in dogs.

Malignant Mediastinal Extra-Adrenal Paraganglioma with Spinal Cord Invasion in a Dog

A 1.5-year-old castrated, male, mixed-breed dog was evaluated because of a 2-week history of lethargy, stiffness, and progressive paraparesis. Spinal radiographs, myelography, and computed tomography of the region showed a locally invasive mass involving the thoracic wall. Upon necropsy, an encapsulated, fluctuant mass was noted attached to the right dorsal body wall in the region of the fifth to seventh thoracic vertebra. Churukian-Schenk staining revealed positive granules within the neoplastic cell cytoplasm and immunohistochemistry was positive for expression for cytoplasmic neuron-specific enolase and synaptophysin. Chromogranin A and S100 expression were found to be negative. Immunohistochemistry and silver staining did not allow further differentiation of the tumor, and the diagnosis remains consistent with either a chromaffin paraganglioma or a nonchromaffin paraganglioma (chemodectoma) with some production of catecholamines. Extra-adrenal paragangliomas are rare neoplasms in dogs but should be considered as a possible differential diagnosis for a primary paraspinal thoracic mass.

Fibrilação atrial em cão associada ao quimiodectoma infiltrativo atrial: relato de caso

Relata-se o caso de um cão, sem raça definida, levado ao veterinário por apresentar cansaço fácil e episódios de síncope. Foram identificadas fibrilação atrial e extra-sístoles ventriculares isoladas ao exame eletrocardiográfico. O tratamento antiarrítmico não foi eficaz, e o animal morreu devido a um episódio de síncope. À necropsia, observou-se massa em região de base cardíaca, invadindo a luz do átrio esquerdo. Histologicamente, constatou-se a presença de quimiodectoma. A infiltração miocárdica atrial causou lesões nos miócitos, produzindo circuitos reentrantes e/ou focos ectópicos de despolarização atrial.

Etiopathogenesis and clinical presentation of carotid body tumors

The carotid body (CB) is a highly specialized small organ located at the bifurcation of the common carotid artery in the neck and plays an important role in acute adaptation to hypoxia. The most common diseased state of the carotid body is its enlargement (i.e., the CB paraganglioma), which can be caused by a genetic predisposition (hereditary paraganglioma, PGL) and by chronic hypoxic stimulation. The CB is the most common tumor site in head and neck paragangliomas. Currently, inactivating germline mutations in the mitochondrial complex II subunits SDHB, SDHC, and SDHD have been identified as genetic risk factors for CB tumors (CBTs). Another locus at chromosome 11q13, identified by linkage analysis in a single family, may harbor a fourth susceptibility gene. Although CBTs are mostly slow-growing and benign, they can cause significant morbidity because of their proximity to major arteries and nerves in the head and neck. Here, we review the etiological factors implicated in the development of CBTs and provide information pertaining to their clinical presentation. Although CBTs are rare, they have the potential to provide unique insights for tumorigenesis and oxygen sensing and signaling mechanisms.

Analysis of factors affecting survival in dogs with aortic body tumors

OBJECTIVE

To evaluate the effect of perioperative and operative variables on survival time in dogs with aortic body tumors.

STUDY DESIGN

Retrospective study.

SAMPLE POPULATION

Twenty-four client-owned dogs with histologically confirmed aortic body tumor.

METHODS

Seventy-eight patient records of dogs seen at the University of Illinois Veterinary Teaching Hospital between 1989 and 1999 with a diagnosis of a heart-base mass were reviewed. Dogs without histologic conformation of an aortic body tumor were excluded. Age; sex; breed; the presence of pleural effusion, pericardial effusion, or abdominal effusion; evidence of cardiac arrhythmias; evidence of distant metastasis; treatment with pericardectomy; treatment with chemotherapy; and time from diagnosis until euthanasia or death were recorded on a spreadsheet. Cox proportional-hazard ratios were used to calculate the relationship of risk variables to survival time. Median survival time was determined using life-table analysis.

RESULTS

Twenty-four dogs met the criteria for inclusion in the study. The median age of dogs with aortic body tumors was 9 years. All dogs had a surgical biopsy performed. Fourteen dogs had a pericardectomy at the time of the biopsy procedure. Of all factors analyzed, only treatment with pericardectomy had a significant influence on survival (P =.0029). Dogs that had pericardectomy survived longer (median survival, 730 days; range, 1-1,621 days) compared with dogs that did not have pericardectomy (median survival, 42 days; range, 1-180 days). This finding was independent of the presence or absence of pericardial effusion at the time of surgery.

CLINICAL RELEVANCE

Dogs that are diagnosed with aortic body tumors may benefit from a pericardectomy at the time of surgical biopsy.

Multiple endocrine neoplasia in a dog

Multiple endocrine neoplasms, including an insulinoma, bilateral adrenocortical adenocarcinomas and an aortic paraganglioma, were diagnosed after euthanasia in a 12-year-old spayed female dog of mixed breed with a history of progressive anorexia, vomiting, diarrhoea, weight loss, polyuria and polydipsia, regenerative anaemia and hypoglycaemia. The clinical, gross pathological, microscopical, immunohistochemical and ultrastructural findings were consistent with the human syndrome of multiple endocrine neoplasia.

Chronic heart disease and its management

Diseases of the cardiovascular system are a common cause of morbidity and mortality among geriatric canine and feline patients. Furthermore, diseases of the heart and vasculature often complicate the management of other abnormalities. This article contains a brief overview of the effects of aging on the circulatory system. It also contains a discussion of the cardiovascular disorders most frequently encountered in geriatric animals, namely, the feline myocardial disorders and feline hypertension and degenerative valvular disease, dilated cardiomyopathy, and cardiac in dogs.

Systemic, metastatic, eu- and heterotope tumours of the heart in necropsied dogs

10,090 dissections of dogs exhibited 2631 neoplastic processes of which 309 involved the heart in the form of eu- and heteropic tumours. The most common primary and/or secondary heart tumour type was hemangiosarcoma (n = 187), followed by paraganglioma (n = 46), carcinoma (n = 33), malignant lymphoma (n = 12), thyroid heart base tumour (n = 9), melanoma (n = 7), mast cell tumour (n = 3) and blastoma (n = 2). The tumour diagnoses were immunohistochemically proved by various antibodies to cytokeratins, vimentin, GFAP, NSE, von Willebrand factor, CD3, CD45RA, S100, thyroglobulin as well as histochemically with argyrophilic, Fontana-Masson and heterochromatic reactions. The odds ratio (OR) for breed and tumour prevalences were determined: German shepherds showed the highest OR for hemangiosarcomas and boxers for paragangliomas.

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.