Thursday, March 24, 2011

Adrenal biopsy and pheo

Adrenal tumors are fairly common. Diagnosis and follow-up of adrenal tumors can be costly and inconvenient. So a reasonable question is "why don't we biopsy an adrenal mass to get a definitive diagnosis?" Here I will try to convince the readers that adrenal biopsy is seldom necessary or useful except in one situation. Most important to me is the one particular safety issue of adrenal biopsy: biopsy of a pheo can be catastrophic.

The one situation where we need adrenal biopsy is to determine the staging of a cancer. For example, one unfortunate patient has lung cancer and an adrenal mass. If the adrenal mass is benign, then the patient's lung cancer is of a lower stage. If the adrenal mass is lung caner metastasis, then the same lung cancer is of an advanced stage. Only biopsy of the adrenal mass will give definitive staging information of the patient's cancer.

Adrenal biopsy is not needed for the vast majority of adrenal masses because the diagnosis of adrenal mass can be confidently made in most patients without biopsy. Let me explain why. How do we know someone has an adrenal mass? Either the patient has clinical symptoms (e.g. paroxysmal hypertension) with suggestive biochemical test results (e.g. elevated plasma metanephrines) so that a functioning adrenal mass (e.g. pheo) is suspected, or CT or MRI is done on the abdomen for some other purposes (such as abdominal pain or cancer staging). In both cases, the imaging characteristics of the adrenal mass tell a lot about it. The size, density, enhancement, and appearance on various MRI protocols all matter. With additional biochemical testing, a good doctor is able to make the correct diagnosis of the adrenal mass.

One may wonder, OK, adrenal biopsy probably is not needed, but will it give important additional information? This issue is a little complicated for non-specialists. For the most common clinical question whether an adrenal mass is adenoma or carcinoma, adrenal biopsy can not answer. Regarding pheo, we just simply do not biopsy a pheo to confirm the diagnosis because doing so is too risky without any benefits.

Although generally very safe, adrenal biopsy can be potentially lethal if done to an unappreciated (or worse, suspected) pheo because of the risk of hypertensive crisis. Here are the basic facts: 5% of all incidentally identified adrenal masses are pheo and the percentage is higher if the mass is pheo-like on imaging. In addition, 6-24% of adrenal masses suspected to be malignancy or metastasis are actually pheo. It is not that every attempted biopsy of a pheo will result in hypertensive crisis. It happens in about 15% of times. Although this number does not sound very high, the extreme danger and the total avoidability of hypertensive crisis makes adrenal biopsy unacceptable in any patients without negative pheo test results.

To prevent hypertensive crisis from happening, ask these following questions before adrenal biopsy:
1. Is this adrenal biopsy really needed? (Answer: only needed for cancer staging.)
2. If adrenal biopsy is needed, have pheo markers been tested? (Answer: please test pheo markers and only do biopsy if the markers are considered negative.)

Dr. Pheo