What Is the Difference Between Paraganglioma and Pheochromocytoma?

Paragangliomas and pheochromocytomas are rare types of tumors that develop from the same type of tissue and are considered a subset of a group of tumors called neuroendocrine tumors (NETs). A NET occurs when specialized cells of the body’s neuroendocrine system grow out of control. Either of these types of tumors can be benign (not cancerous) or malignant (cancerous).

The difference between paragangliomas and pheochromocytomas is where they form:

• Paragangliomas form in nerve tissue in the adrenal glands and near certain blood vessels and nerves
• Pheochromocytomas are types of paragangliomas that form within the center of the adrenal gland (adrenal medulla)

The adrenal glands produce hormones called catecholamines, such as adrenaline (epinephrine) and noradrenaline (norepinephrine). These catecholamines help control heart rate, blood pressure, blood sugar, and the way the body reacts to stress. Paragangliomas and pheochromocytomas can cause the adrenal glands to release extra catecholamines into the blood, which may cause signs or symptoms.

If paragangliomas and pheochromocytomas do not make extra catecholamines, they may not cause any symptoms. Symptoms of paragangliomas and pheochromocytomas that occur when too much adrenaline or noradrenaline is released into the blood may include: 

• High blood pressure (hypertension) (the most common symptom)
• Headache
• Heavy sweating for no known reason
• Strong, fast, or irregular heartbeat
• Shaking
• Extremely pale skin

The cause of paragangliomas and pheochromocytomas is unknown. They may be due to certain genetic changes but the reason these changes occur is not understood. 

Risk factors for developing paragangliomas and pheochromocytomas include certain inherited (genetic) syndromes such as: 

• Multiple endocrine neoplasia 2 syndrome, types A and B (MEN2A and MEN2B)
• von Hippel-Lindau (VHL) syndrome
• Neurofibromatosis type 1 (NF1)
• Hereditary paraganglioma syndrome
• Carney-Stratakis dyad (paraganglioma and gastrointestinal stromal tumor [GIST])
• Carney triad (paraganglioma, GIST, and pulmonary chondroma)

Symptoms of paragangliomas and pheochromocytomas can also be triggered by certain situations, such as:

• Intense physical activity
• Physical injury 
• Emotional stress
• Childbirth
• General anesthesia
• Surgery, including procedures to remove the tumor
• Eating foods high in tyramine (such as red wine, chocolate, and cheese)

Paragangliomas and pheochromocytomas are diagnosed with a physical examination and patient history, along with tests and procedures such as:

• Twenty-four-hour urine test to measure amounts of catecholamines in the urine
• Blood catecholamine studies 
• Computerized tomography (CT) scan 
• Magnetic resonance imaging (MRI)
• Genetic testing and counseling 

Patients diagnosed with paraganglioma or pheochromocytoma are usually advised to have genetic counseling to determine their risk for having an inherited syndrome and other related cancers

Genetic testing may be recommended for patients who:   

• Have personal or family history of traits linked with inherited paraganglioma or pheochromocytoma 
• Have tumors in both adrenal glands
• Have multiple tumors in one adrenal gland
• Have signs or symptoms of excess catecholamines released into the blood or malignant (cancerous) paraganglioma
• Are diagnosed before age 40

After paragangliomas and pheochromocytomas are diagnosed, further tests are indicated to determine whether the tumor has spread to other parts of the body, such as:

• Computerized tomography (CT) scan 
• Magnetic resonance imaging (MRI)
• MIBG (meta-iodobenzylguanidine) scan
• Octreotide scan
• FDG-PET scan (fluorodeoxyglucose-positron emission tomography scan)

Treatment for paragangliomas and pheochromocytomas may include one or more of the following: 

• Medications
  • Drugs to manage blood pressure such as alpha-blockers
  • Drugs to keep the heart rate normal such as beta-blockers  
  • Drugs to block the effect of extra hormones made by the adrenal gland
• Surgery
  • Removal of one or both adrenal glands (adrenalectomy) 
  • If both adrenal glands are removed, hormone therapy to replace hormones made by the adrenal glands is needed for life
• Radiation therapy
  • External radiation therapy 
  • Internal radiation 
  • MIBG therapy 
• Chemotherapy
• Ablation therapy    
  • Radiofrequency ablation    
  • Cryoablation
• Embolization therapy
• Targeted therapy
• Sunitinib (a type of tyrosine kinase inhibitor) 
• New treatments being tested in clinical trials