Pheochromocytoma is a tumor of the adrenal gland. This tumor is typically benign (not cancerous) and can be cured by surgical removal. However, pheochromocytomas produce neurohormones called cateholamines (epinephrine and norepinephrine). High levels of catecholamines can result in high blood pressure, headaches, sweating, heart palpitations, nausea, vomiting, and other symptoms. These tumors are considered dangerous because of their unpredictable behavior. Patients with pheochromocytoma may experience blood pressures high enough to cause a stroke or heart attack in patients.