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Cardiovascular system


Vascular disorders
Congenital heart defects
Cardiac arrhythmias
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Pericardial disorders
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Cardiovascular system pathology review



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High Yield Notes
13 pages


14 flashcards

USMLE® Step 1 style questions USMLE

4 questions

A 44-year-old woman is brought to the emergency department an hour after developing acute confusion. According to her husband, the patient had been experiencing headaches and blurry vision for the past several hours. She has no significant past medical history. Temperature is 37.0°C (98.6°F), pulse is 102/min, and blood pressure is 205/110 mmHg. Physical examination shows right-sided weakness and loss of sensation. A CT scan of her head demonstrates an intraparenchymal hemorrhage. Despite appropriate treatment, the patient dies. A postmortem biopsy of her left adrenal gland is shown below:

Image reproduced from Wikimedia Commons

This patient most likely also experienced which of the following symptoms?

External References

In pheochromocytoma, pheo- means dark, chromo- refers to color, cyto- refers to a cell and -oma means tumor. So a pheochromocytoma is a rare adrenal gland tumor where the cells darken when they form tumors.

Now, there are two adrenal glands, one above each kidney, and each one has an outer layer called the cortex and an inner layer called the medulla.

In the medulla, there are cells called chromaffin cells and their job is to make hormones called catecholamines. The catecholamines include epinephrine and norepinephrine - the fight or flight hormones.

Normally, the chromaffin cells in the adrenal gland secrete epinephrine and norepinephrine into the blood when something scary happens - like someone saying BOOM!

The epinephrine and norepinephrine bind to alpha and beta receptors in various tissues throughout our body and cause an increase in cardiac output, increased blood pressure, dilated pupils, increased blood flow to skeletal muscles, and increased blood sugar.

Pheochromocytomas are tumors that form when these chromaffin cells start to divide uncontrollably.

They typically form in one of the adrenal glands, but rarely can be in both and sometimes can even develop in other parts of the body where chromaffin cells are found like the carotid arteries in the neck, the bladder, and the abdominal aorta.

Most pheochromocytomas arise sporadically, but some are associated with an inherited syndrome.

One of these is multiple endocrine neoplasias type 2A and type 2B, where pheochromocytoma is caused by a mutation in the RET gene, which is a protooncogene that encodes for proteins that promote cell growth and division.

When the RET gene mutates, it becomes an oncogene that causes the cells to divide constantly.

Another disease associated with pheochromocytomas is Von Hippel-Lindau disease, which develops when there’s a mutation in the VHL gene which codes for the von Hippel-Lindau tumor suppressor protein.

Tumor suppressor proteins normally inhibit cell growth and division and mutations result in uncontrolled cell proliferation leading to tumors.

A third disease is neurofibromatosis type 1, which is caused by a mutation in the gene NF1 that encodes for another tumor suppressor protein called neurofibromin, and the mechanism here is similar to Von Hippel-Lindau disease.

Once pheochromocytomas develop, they cause problems by releasing too many catecholamines into the blood. The catecholamine release is unregulated and could happen continuously or at random times.

However certain things like stress, physical exertion, or even certain foods that contain the molecule tyramine like chocolate, cheese, and wine can trigger the release of catecholamines.

Imagine getting stressed, and then going to the gym, and then indulging in a plate of chocolate and cheese washed down with a glass of wine - a recipe for triggering catecholamine release!


A pheochromocytoma is a neuroendocrine tumor of chromaffin cells in the adrenal medulla. Pheochromocytomas cause problems by producing too much of the catecholamines epinephrine and norepinephrine, which then causes sympathetic nervous system hyperactivity, resulting in symptoms like high blood pressure, headaches, palpitations, and sweating.

Pheochromocytomas are diagnosed by testing the urine for catecholamines and metanephrine; and imaging studies such as CT or MRI. Treatment involves surgical removal of the tumor, and medications to control blood pressure and heart rate.

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