Chemodectoma

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(Redirected from Paraganglioma)
A carotid body tumor (chemodectoma) just craniomedial of the ECA in a dog[1]
Aortic body tumor of a dog[2]

Chemodectoma (paraganglioma) are a rare slow-growing neuroendocrine neoplasia of canine heart.

Chemodectoma are chemoreceptor tumors which originate from paraganglial chromaffin-negative glomus cells of the embryonic neural crest. These are tumors of the chemoreceptor organs which detect changes in arterial blood oxygen, carbon dioxide and pH[1], usually found at the heart base but can sometimes be found within the myocardium[3].

A number of forms have been recognized in dogs:

  • Carotid body tumor
  • Aortic body tumor

Although they are usually associated with the carotid or aortic body, they have also been reported in the tympanic cavity and inferior vagal ganglion. Carotid body tumors appear less frequent and are usually more malignant than aortic body tumors, which are usually non-functional[4]. The generally secrete catecholamines and serotonin, which complicates the clinical presentation[5].

Metastases are commonly found in regional lymph nodes and most visceral organs[6][7], and concurrent unrelated tumors have also been found[8].

Affected dogs are usually older, brachycephalic dogs such as the Boxer, and symptoms are referable to with cardiac disturbances associated with mass lesions[9]. In brachycephalic breeds, their facial abnormalities cause chronic hypoxia and are suspected to provide a cause of hyperplasia and, finally, neoplasia of chemoreceptor cells[1].

Coughing, reduced exercise tolerance, dyspnea and episodic syncope are commonly observed symptoms[10]. Pericarditis and cardiac tamponade are frequent sequelae and tracheobronchial lymphadenopathy may be observed in some cases.

Diagnosis is based on radiographic or ultrasonograpic finding of a mediastinal or cardiac mass.

A definitive diagnosis usually requires histological analysis of biopsies and immunohistochemical expression of chromogranin A, vimentin, synaptophysin and neuron-specific enolase[11][12]. Histologically, these tumors show pleomorphism, anisocytosis and anisokaryosis and the presence of mononuclear giant cells[13].

A differential diagnosis would include other thoracic-based tumors, including lymphoma, osteosarcoma, Coccidioides spp, Aspergillus spp, Nocardia spp, Penicillium spp, Mycobacterium spp and other neuroendocrine diseases[14].

Some tumors are surgically non-resectable as they tend to splay the carotid bifurcation as they enlarge[15].

They may benefit from radiation therapy.

References

  1. 1.0 1.1 1.2 Kromhout K et al (2012) Magnetic resonance and computed tomography imaging of a carotid body tumor in a dog. Acta Vet Scand 54:24
  2. Noszczyk-Nowak A et al (2010) Cases with manifestation of chemodectoma diagnosed in dogs in Department of Internal Diseases with Horses, Dogs and Cats Clinic, Veterinary Medicine Faculty, University of Environmental and Life Sciences, Wroclaw, Poland. Acta Vet Scand 52:35
  3. Nowak M et al (2008) Infiltrative form of a tumour in cardiac base in a dog with dilated cardiomyopathy: clinical and morphological correlations. A case report. Bull Vet Inst Puławy 52:485–490
  4. Obradovich JE et al (1992) Carotid body tumors in the dog. Eleven cases (1978-1988). J Vet Intern Medicine 6(2):96–101
  5. Kay JM & Laidler P (1977) Hypoxia and carotid body. J Clin Path 11:30–44
  6. Szczech GM et al (1973) Chemodectoma with metastasis to bone in a dog. J Am Vet Med Assoc 162(5):376–378
  7. Callanan JJ et al (1991) Metastatic aortic body tumour causing neck pain in a dog. J Small Anim Pract 32(10):525–528
  8. Sterczer A et al (2011) A case of synchronous hepatocellular carcinoma and aortic body chemodectoma in a dog - pathological case report. Acta Vet Hung 59(1):113-121
  9. Noszczyk-Nowak A et al (2010) Cases with manifestation of chemodectoma diagnosed in dogs in Department of Internal Diseases with Horses, Dogs and Cats Clinic, Veterinary Medicine Faculty, University of Environmental and Life Sciences, Wroclaw. Poland. Acta Vet Scan 52:35
  10. Rancilio NJ et al (2012) Use of three-dimensional conformal radiation therapy for treatment of a heart base chemodectoma in a dog. J Am Vet Med Assoc 241(4):472-476
  11. Brown P et al (1997) Immunohistochemical characteristics of canine aortic and carotid body tumours. J Am Vet Med Assoc 211:736–740
  12. Deim Z et al (2007) Carotid body tumor in dog: a case report. Can Vet Journal 48(8):865–867
  13. Yamamoto S et al (2013) Histopathological and Immunohistochemical Evaluation of Malignant Potential in Canine Aortic Body Tumours. J Comp Pathol Feb 25
  14. Jones BG & Pollard RE (2012) Relationship between radiographic evidence of tracheobronchial lymph node enlargement and definitive or presumptive diagnosis. Vet Radiol Ultrasound 53(5):486-491
  15. Deim Z et al (2007) Carotid body tumor in dog: a case report. Can Vet Journal 48(8):865–867