Welcome back. Thanks for joining me on this discussion of pheochromocytoma in the section of
general surgery. Pheochromocytoma used to be one of my favorite topics as a medical student
because the word is kind of fun to say. I challenge you to say it ten times fast. Now, let’s get started.
Pheochromocytomas are catecholamine secreting tumors specifically located the vast majority
of the time in the adrenal medulla. Remember, the adrenal gland has multiple layers. In the inner
core called the adrenal medulla, norepinephrine and epinephrine are secreted. Also important
to remember, 10% of pheochromocytomas are actually outside of the adrenal gland. These are
commonly called paragangliomas or organ of Zuckerkandl. In this image marked in red is the organ
of Zuckerkandl or a paraganglioma commonly found at the aortic bifurcation. They contain neural
crest tissue usually at the level of the aortic bifurcation or at the inferior mesenteric artery takeoff.
What are some of the common symptoms of pheochromocytoma? Here, you see
the gentleman with episodic headaches. They can be quite severe. Diaphoresis, also catecholamine-induced;
and very importantly, tachycardia. Now, the combination of episodic headaches, diaphoresis,
and tachycardia is a classic association and incredibly high-yield. I recommend that you keep
that in mind. However, clinically, this triad is actually a rare finding. Remember very importantly,
pheochromocytomas can result in potentially fatal cardiac arrhythmias. Therefore, you must have
a high index of suspicion in patients with difficult to treat hypertension. Speaking of which,
most patients with pheochromocytoma result in hypertension and the reason is because of the
increased catecholamine secretions. Let’s take a look at what laboratory findings may help
you diagnose a pheochromocytoma. Unfortunately, your general chemistries and your CBCs
may not be very helpful. However, specific to the diagnosis of pheochromocytoma are urine
or plasma metanephrines. Plasma metanephrines are more sensitive but less specific
and conversely, urine catecholamines and metanephrines are less sensitive but more specific.
A downfall of urine catecholamines is that it requires a 24-hour urine collection.
That can be difficult on an outpatient basis.