Chemoreceptor Organ Pathology

Question 1

Define a chemoreceptor

Answer 1

a special nerve cell that detects changes in the chemical composition of blood (CO2, O2 and pH) and send information to the brain to regulate the CV and resp functions (HR, BP and RR)

Question 2

Name the most important chemoreceptors

Answer 2

carotid body
aortic body

Question 3

Histology of a chemodectoma

Answer 3

nests and packets
similar fibrovascular stroma
benign
+/- signs of malignancy (mitosis, anisocytosis, necrosis, haemorrhages)

Question 4

What is the most common neoplasm of the aortic body and its predisposing factors ?

Answer 4

adenoma
non-functional
brachycephalic breeds and hypoxia

Question 5

Gross description of a heart base tumour

Answer 5

single, multinodular
physically, white to tan, firm and smooth
attached to the adventitia of the aorta/pulmonary a.
dark red with brown discolouration
grow a lot and can invade atria

Question 6

Most common neoplasms of the carotid body

Answer 6

adenomas (encapsulated, <4cm, smooth, firm, white with haemorrhages, vascularised)
carcinomas (irregular, multinodular, >4cm, affect more surrounding structures)

Question 7

Heart Base Neoplasms derived from ectopic thyroid tissue - predispositions and distinguishing features from chemodectomas

Answer 7

5-10% of all heart base tumours
hypoxia and brachycephalic breeds
smaller cells, hypereosinophilic cytoplasm, primitive follicular structures, test through IHC

Question 8

Define an extra-adrenal paraganglioma

Answer 8

a paraganglioma that can occur anywhere in the body - rarely seen in animals