Chemodectoma

From Felipedia

Feline heart showing a large, partially encapsulated chemodectoma with multiple necrotic foci

Heart, chemodectoma; cat. Neoplastic cells are arranged in closely packed lobules separated by thin fibrovascular stroma.

Chemodectoma, or extra-adrenal nonchromaffin paraganglioma, is a rare heart disease of cats^[1].

This neoplasm aries from chemoreceptor cells involved in the response to changes in blood pH, oxygen tension, and carbon dioxide content^[2]. Chronic hypoxia is probably involved in the pathogenesis of chemodectoma: a high prevalence of this tumor has been recorded both in humans and in cattle living in mountain areas and in brachicephalic dogs, which have an upper respiratory tract anatomic conformation that favors a chronic hypoxic status. Chemodectomas most commonly arise within the aortic or the carotid body and, less frequently, in the glomus pulmonale, in the glandula suprarenalis, or in ectopic sites^[3].

Clinical signs

Cases often present with severe inspiratory dyspnea and cyanosis. Clinical and radiographic examination reveal a severe thoracic effusion. Serology for feline immunodeficiency virus, feline leukemia virus, and feline coronavirus is usually negative and hematology and clinical chemistry unremarkable. Cytology of the pleural fluid is characterized by neutrophils, mostly nondegenerate, macrophages, and reactive mesothelial cells (modified transudate)^[4].

Diagnosis

To date, two carotid body tumors, one cauda equina paraganglioma, and eight aortic body tumors have been reported in cats^[5]. Aortic body tumors are locally extensive, multilobulated masses, located within the pericardium at the heart base. They are usually encapsulated and organized in small lobules surrounded by a prominent fibrovascular stroma. Neoplastic cells commonly stain for neuron-specific enolase (NSE), chromogranin A (CgA), and synaptophysin (SY).

Thoracocentesis, radiography and ultrasound imaging of the chest reveal the presence of nodule, located at the heart base and surrounding the large vessels^[6].

Treatment

Chemodectomas are intimately associated with vascular structures, making complete surgical excision and radiation therapy problematic.

The use of chemotherapy for chemodectomas in cats has not been reported^[7]

Because of the poor prognosis, most cats are euthanased.

References

1. ↑ Paola JP, et al (1994) Aortic body tumour causing pleural effusion in a cat. J Am Anim Hosp Assoc 30:281-285
2. ↑ Buergelt CD, Das KM (1968) Aortic body tumour in a cat: a case report. Vet Pathol 5:84-91
3. ↑ Caruso KJ, et al (2002) Intrathoracic mass in a cat. Vet Clin Pathol 31:193-195
4. ↑ Carpenter JL, Andrews LK, Holzworth J (1987) Tumors and tumor-like lesions. In: Diseases of the Cat, ed. Holzworth J, pp 406-411, WB Saunders, Philadelphia
5. ↑ Tilley, LP et al (1981) Cardiovascular tumors in the cat. J Am Vet Med Assoc 17:1009
6. ↑ George C, Steinberg H (1989) An aortic body carcinoma with multifocal thoracic metastases in a cat. J Comp Pathol 101:467-469
7. ↑ August, JR (2010) Consultations in feline internal medicine. Vol 6. Elsevier Saunders, Philadelphia. pp:704-705