As the readers
may have guessed, I have been extremely busy (due to increased workload) in the
last few months. That’s why I haven’t written anything in the last 4 months. I found
some time at the Memorial Day weekend to write this post.
An interesting
study was published in May about small pheos. Small pheos are more commonly
seen in these days. In the last year alone, at least 5 physician colleagues discussed
with me about small pheos. There is no official definition of a “small” pheo
but the authors call anything less than 3 cm in diameter as small. I actually
agree with the authors in the 3 cm cutoff. In the past, I reviewed the
literature on pheo-induced cardiomyopathy and noted all the tumors that cause
cardiomyopathy are equal or larger than 3 cm. An inquisitive reader may wonder
why doctors only use one dimension in describing tumor size. On one hand,
doctors are lazy and one dimension is easier to remember; on the other hand,
most pheos are nice and round. I have yet to see an odd-shaped pheo, say one
resembling the shape of a cucumber. Of course you never know.
There are 3 main
findings in the paper. First, about 1/3 of all pheos in the last 15 years are “small”
(<3 cm). Second, small pheos do not usually cause hypertension or other
classical pheo symptoms but some small pheos ironically cause hypertensive
crisis during an unrelated surgical procedure. So if one has a small pheo and
hypertension, the hypertension unlikely gets better after pheo removal. I
recently had a patient with small pheo whose blood pressure actually got worse
after pheo removal. Third, small pheos have typical appearance on CT/MRI but
the biochemical test results can be borderline or in the cases of very small
pheos (i.e. <1 cm), even normal. In my earlier posts, I emphasized that most
borderline test results are false positive. That statement is still correct but
I need to add some qualifications now. If an adrenal tumor is small but has typical
pheo appearance on CT/MRI, and the test results are borderline, it has a good
chance to be a real (small) pheo!
Pheo is a humbling tumor. The more I know about it, the more careful I become when I
make a diagnosis. I begin to question myself whether I was absolutely right
when I told my patients with normal biochemical test results “You don’t have
pheo.” They might still have a very small pheo. Now I use a buzz phrase “clinically
significant pheo.” I tell my patients if they likely or unlikely have a “clinically
significant pheo” rather than if they have pheo or not. Nobody can say for sure
whether a patient has a very small pheo. The good news is that very small pheos
are clinically insignificant.
Dr. Pheo
