Chemodectoma

From Felipedia

Fig. 1. Heart, cut surface; cat. Large, partially encapsulated mass with multiple necrotic foci, which surrounds and constricts the pulmonary vein and pushes the aorta dorsally. Right atrium and ventriculum are severely dilated. Bar = 12.5 mm. Fig. 2. Heart, chemodectoma; cat. Neoplastic cells are arranged in closely packed lobules separated by thin fibrovascular stroma. HE. Bar = 45 µm. Fig. 3. Heart, chemodectoma; cat. High magnification of a neoplastic lobule: neoplastic cells are round to polygonal with indistinct cell borders, scant cytoplasm, and a central, round nucleus with fine chromatin and one or two prominent nucleoli. HE. Bar = 220 µm.

Introduction

Chemodectoma, or extra-adrenal nonchromaffin paraganglioma, is a neoplasm arising from chemoreceptor cells involved in the response to changes in blood pH, oxygen tension, and carbon dioxide content. 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. Chemodectomas are particularly rare in cats: to date, two carotid body tumors, one cauda equina paraganglioma, and eight aortic body tumors have been reported in cats. 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)[1].

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).

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

Treatment

Because of the poor prognosis, most cats are euthanased.

References

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