Pheochromocytoma - Prevalence, Symptoms, Causes, and Treatment

What Is Pheochromocytoma?

Pheochromocytoma is a rare tumor of the adrenal gland. It is a type of neuroendocrine tumor that grows from chromaffin cells of the adrenal gland. It results in increased secretion of epinephrine (adrenaline) and norepinephrine (noradrenaline), and dopamine. These hormones are collectively called catecholamines. These hormones regulate heart rate, metabolism, and blood pressure. Most pheochromocytomas are benign, and they do not spread to other parts of the body. Only about ten percent of the pheochromocytomas turn malignant. About 80 % to 85 % of pheochromocytomas grow in the inner layer of the adrenal gland (adrenal medulla). And about 15 to 20 % develop outside of this area in the chest, heart, abdomen, pelvis, bladder, the base of the skull, etc., and are called paragangliomas.

How Common Is Pheochromocytoma?

Most cases of pheochromocytomas affect people who are between 30 to 50 years of age. It is a rare condition, estimated to be occurring in only about eight in one million people. However, this ratio may be different because many pheochromocytoma cases go undiagnosed.

What Are the Symptoms of Pheochromocytoma?

Some patients with pheochromocytoma may be asymptomatic (do not develop or show any symptoms). However, hypertension, which can suddenly occur in 45 % of patients, is known to be a prominent symptom. These paroxysmal attacks may happen due to palpation of the tumor, posture change, massage, anesthesia, emotional trauma, abdominal compression, etc. These attacks may last from a few minutes to hours, and they often show a set of symptoms that include:

• Increased blood pressure.

• Increased palpitation of the heart.

• Headaches.

• Profuse sweating.

These symptoms occur due to excessive secretion of certain hormones known as catecholamines.

Other symptoms of pheochromocytoma are:

• Chest pain.

• Abdominal pain.

• Nausea or vomiting.

• Diarrhea.

• Epigastric pain.

• Visual disturbance.

• Constipation.

• Pale skin.

• Weight loss.

• Shortness of breath (dyspnea).

• Seizures.

• Abnormally rapid breathing (tachypnea).

• Diabetes.

• Loss of sleep (insomnia).

• Anxiety attacks.

What Causes Pheochromocytoma?

The exact cause of pheochromocytoma is unknown. Most cases occur sporadically for unknown reasons, but about 35 % of the total cases arise due to genetic changes to specific genes. Scientists have reported mutations in about 20 different genes that may lead to pheochromocytoma. In other cases, pheochromocytomas occur as part of a genetic syndrome, a disorder in which pheochromocytomas are secondary, along with other endocrine neoplasia.

Who Is More Affected by Pheochromocytoma?

Pheochromocytomas affect males and females equally, and they may affect people at any age. However, the tumor occurs mainly between 30 to 50 years of age. And approximately ten percent of the total number of cases occur in children. Because most pheochromocytomas are undiagnosed, it is challenging to determine the incidence of the disease. In addition, people with rare inherited disorders are at a higher risk of pheochromocytoma, and tumors associated with these conditions are also more likely to be cancerous. Examples of such inherited diseases include:

• Multiple Endocrine Neoplasia Type 2- It is a hereditary condition that is primarily associated with three types of tumors which are medullary thyroid tumors, parathyroid tumors, and pheochromocytomas.

• Von-Hippel Lindau Disease- It is an inherited disorder that results in the development of tumors and cysts in different parts of the body.

• Neurofibromatosis- It is a genetic disorder that causes tumors to develop in the brain, spinal cord, and nerves.

• Hereditary Paragangliomas Syndrome- It is a rare genetic disorder characterized by the presence of tumors called paragangliomas found in the paraganglia.

Does Pheochromocytoma Run in Families?

About 25 % to 35 % of the total pheochromocytoma cases can be inherited, which means they are passed on from parents to children. In addition, some inherited pheochromocytomas may be associated with genetic variations like endocrine neoplasia, Von Hippel-Lindau syndrome, etc.

How Is Pheochromocytoma Diagnosed?

Pheochromocytomas may be symptomatic or asymptomatic. Therefore, a diagnosis based on clinical signs and symptoms cannot be 100 % accurate. However, a detailed study of the patient’s history is significant and a thorough clinical evaluation. Hence, the following test should be performed and symptoms evaluated.

1. Check for Paroxysmal Attacks- Symptoms are episodic, and they may occur from several times a day to only a couple of times a month. On the other hand, paroxysmal attacks are intensified symptoms that last for a short period. The characteristic signs of a paroxysmal attack are high blood pressure, profuse sweating, irregular heartbeat, and headaches.

2. Laboratory Analysis of Blood or Urine- Blood and urine analysis can easily confirm a diagnosis of a secreting pheochromocytoma by the increased levels of catecholamines or their metabolites in the blood or urine sample of the patient.

3. Imaging Tests- Computed tomography (CT scan) and magnetic resonance imaging (MRI) are performed to determine the location and size of the tumor. They also check if the tumor has spread to other body parts. Lobenguan I 123 injections and Gallium 68 Dotatate are imaging agents for detecting rare endocrine tumors in children.

4. Other Tests- Other tests may include; adrenal biopsy, glucose test, metanephrine blood tests, abdominal positron emission tomography (PET) scan, metaiodobenzylguanidine (MIBG) scintiscan, etc.

How Is Pheochromocytoma Treated?

The treatment procedures for pheochromocytoma are determined by numerous factors; tumor size, tumor location, whether the tumor is cancerous or non-cancerous, if the tumor is localized or has spread to other body parts, patient’s age and health, etc. Therefore, the potential risks, side effects, and long-term effects on a patient’s health should be discussed beforehand. Treatment options include:

• Medications- Symptomatic relief is given with the help of medicines such as alpha-blockers and beta-blockers to control high blood pressure during a paroxysmal attack. In cases where surgery cannot be done, medication is again used to control the high levels of hormones in the blood and manage their effect.

• Surgery- It is generally the primary treatment modality for pheochromocytomas. Many cases are successfully treated by surgically removing the tumor from the patient’s body. Laparoscopic adrenalectomy is the most common surgical procedure. A small incision is made in the abdomen, a laparoscope is inserted, and the tumor is removed. Before surgery, the patient’s blood pressure and other vitals should be normalized with drugs.

• Radiation Therapy and Chemotherapy- Radiation and chemotherapy are done in patients where the tumor is cancerous and has spread to other body parts. However, these treatments are not very effective in treating the tumor.

What Is the Prognosis of Pheochromocytoma?

The prognosis of the disease depends on the following factors:

1. Location of the tumor.

2. If the tumor has spread to other parts of the body.

3. How much of the tumor has been surgically removed from the body.

Patients with small pheochromocytomas that have not spread to other body parts have a 95 % chance of a successful five-year survival rate. Patients with recurrent tumors or tumors that have spread to other body parts have a five-year survival rate of up to 60 %. People treated for pheochromocytomas should regularly see a doctor and get their testing done to ensure the tumor has not recurred.

Conclusion:

Pheochromocytomas are rare adrenal gland tumors that result in over secretion of epinephrine and norepinephrine. Clinical symptoms like paroxysmal attacks characterize the condition. The tumor may affect men and women equally and affect people of any age. The state is often inherited. A timely diagnosis and treatment can help manage the tumor and prevent it from getting cancerous.