Small and very small pheos

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