Adrenal incidentaloma

An adrenal incidentaloma is a mass in an adrenal gland that turns up when nobody was looking for it. The adrenal glands sit on top of the kidneys and make hormones, the body's chemical messengers. The mass is clinically inapparent: it causes no symptoms and gives no signs that it's there. That's why it's found by chance, while someone is being tested or treated for something else, like belly pain or back pain. It's like looking at a photo you took to show off your couch and spotting a stain on the wall in the corner that you'd never noticed: you weren't looking for it, but there it is. That's where the name comes from. It's an incidental finding, so it's called an incidentaloma.

Here's what might be behind it. Most of these masses are adenomas, which are benign tumors, meaning they aren't cancer. But some can be malignant, or cancerous, and others can release hormones autonomously: on their own, without following the body's usual signals. The tricky part is that this hormone release can be so subtle, or so on-and-off, that it leaves no signs anyone would notice when examining the person.

The most common case involves cortisol, a hormone made by the adrenal gland. Normally the gland releases cortisol when it gets the signal from corticotropin, or ACTH, another hormone that works like the light switch for cortisol production. In mild autonomous cortisol secretion, the tumor releases cortisol without waiting for that signal, like a lamp that turns on by itself when nobody has touched the switch. And it does this without causing the typical picture of hypercortisolism, the set of changes that too much cortisol causes in the body.