Paraganglioma seen in-

CAROTID BODY TUMOUR (chemodectoma, CAROTID BODY PARAGANGLIOMA). Carotid body tumour arises in the carotid bodies which are situated at the bifurcation of the common carotid aeries. Carotid bodies are normally pa of the chemoreceptor system and the cells of this system are sensitive to changes in the pH and aerial oxygen tension and are also the storage site for catechola- mines. Histologically similar tumours are found in other parasympathetic ganglia represented by the vagus and glomus jugulare (jugulotympanic bodies,). Carotid body paragangliomas, as they are currently called, are rare tumours and occur between 3rd and 6th decades of life with slight female preponderance. A few (5%) are bilateral and some show familial incidence. Grossly, they are small, firm, dark tan, encapsulated nodules. Microscopically, well-differentiated tumour cells form characteristic organoid or alveolar pattern, as is the case with all other neuroendocrine tumours. The tumour cells contain dark neurosecretory granules containing catecholamines. These tumours are mostly benign but recurrences are frequent. Ref: TEXTBOOK OF PATHOLOGY 6th EDITION - HARSH MOHAN PAGE NO:521