Catecholamines are hormones that increase the heart rate, blood pressure, rate of breathing and amount of energy available to the body. Adrenaline is the most common and well-known catecholamine. The adrenal medulla releases extra adrenaline in response to stress. This increase is known as the "fight or flight response"—i.e. the body is ready to fight or run. Paragangliomas are rare tumors that make too much adrenaline. Paraganglioma are found in 2 out of every million people each year and is the cause of high blood pressure in less than 0.2% of people with high blood pressure. However, because paraganglioma release adrenaline in uncontrolled bursts, they can cause serious health problems like stroke, heart attacks, and even death. For this reason, many doctors call it the "pharmacologic time bomb." Paraganglioma can occur at any age and there are no known risk factors except for certain genetic syndromes. Up to 25% of paragangliomas are inherited.
Even after removing the tumor it is often impossible to tell the difference between a malignant and benign paraganglioma under the microscope. The only definite way to tell if it is a malignant paraganglioma is if there is spread into nearby organs (i.e. local invasion), spread to distant sites like the lung and bone (i.e. metastases), or cancer that comes back (i.e. recurrence).