<s>[INST] context: Paraganglioma are clusters of neuroendocrine cells associated with the sympathetic and parasympathetic nervous system.
Paraganglioma is the tumor of neuroendocrine cells of these paraganglia that occurs at various body sites including head, neck, thorax and abdomen.
Most common location of paragangliomas is adrenal medulla, where they are referred to as pheochromocytomas.
Other locations are


Paravertebral ganglion (organs of zuckerkandl and rarely bladder)
Paraganglia related to the great vessels of head and neck, so called aorticopulmonary chain, including carotid bodies (most common); ganglion nodosum of vagus nerve; and clusters located about the oral cavity, nose nasopharynx, larynx, and orbit.


Microscopic features of Paraganglioma are:


Composed of nests (zellballen) of round to oval chief cells (neuroectodermal origin) that are surrounded by delicate vascular septa.
Chief cells stain strongly for neuroendocrine markers such as chromogronin, synaptophysin, neuron specific enolase, CD56 and CD57.
There is a supporting stroma of spindle-shaped cells (sustentacular cells), that are positive for S-100 protein.
Neuroendocrine granules [/INST] question: Paraganglioma seen in -a) Carotid body tumorb) Thoraxc) Para-vertebral locationd) Para-aortic lymph nodes | options: A: ab B: bc C: acd D: abc | answer: D </s>