All are true about pheochromocytoma, except:

Pheochromocytoma may occur as a single tumor or as more than one growth. It usually develops in the center (medulla) of one or bothadrenal glands. Rarely, this kind of tumor occurs outside the adrenal gland, usually somewhere else in the abdomen.Very few pheochromocytomas are cancerous around 10%. The tumors may occur at any age, but they are most common from early to mid-adulthood. Pheochromocytoma follows a rough rule of tens - 10% cases are not associated with hypeension 10% are extra - adrenal and of those 10% are extra - abdominal 10% cases occur in children 10% cases affect both adrenals 10% cases have metastatic potential (malignant) Ref: CMDT 2008 Edition, Page 1012