Following is true about pheochromocytoma except ?

Ans. is 'c' i.e., 90% of non familial cases are bilateral Pheochromocytoma Pheochromocytoma is a neoplasm of chromaffin cells which usually arise from adrenal medulla. About 10% of these tumors arise at extraadrenal sites, where they are called paraganglioma : When pheochromacytomas arise at extra-adrenal site, they are referred to as paraganglioma. Paraveebral paragangliomas secrete catecholamines. Pheochromocvtoma The tumor is composed of polygonal to spindle shaped chromaffin cells or chief cells, clustered with sustentacular cells into small nests or alveoli (zellballen) by a rich vascular network. The nuclei are usually round to ovoid, with a stippled " salt & pepper" chromatin that is characteristic of most neuroendocrine tumors. Zellballen pattern are seen in paraganglioma. Pheochromocytomas usually subscribe to a convenient "rule of 10s" :- 10% of pheochromocytomas arise in association with one of several familial syndromes. These include the MEN-2A & MEN-2B syndromes, type I neurofibromatosis, von Hippel-Lindau syndrome & Sturge-Weber syndrome. 10% of pheochromocytomas are extra-adrenal, occurring in sites such as organ of Zuckerkandl & carotid body, where these chromaffin-negative tumors are usually called paragangliomas to distinguish them from pheochromocytomas. 10% of nonfamilial adrenal pheochromocytomas are bilateral; this figure may rise to 70% in cases that are associated with familial syndromes. 10% of adrenal pheochromocytomas are biologically malignant, although the associated hypeension represents a serious & potentially lethal complication of even "benign"tumors. 10% of adrenal pheochromocytomas arise in childhood, usually the familial subtypes, and with a strong male preponderance. The nonfamilial pheochromocytomas most often occur in adults between 40 & 60 years of age, with a slight female preponderance.