TST

The nurse looked at the small pinkish area on my forearm.

It wasn't raised but was, naturally, noticeable.

"It's fine", she said.

And like that, it was over.

Yay!

That was the Tuberculin Skin Test (TST), which I had done three days prior. A TST, otherwise known as a Mantoux, is used as an initial indicator of tuberculosis (TB) through the detection of Mycobacterium tuberculosis. It involves a 0.1ml intradermal injection of tuberculin on the anterior forearm, with the resulting induration (raised, hard area) measured (but not including the erythema (red swelling bit)). While the size of the induration varies depending on local health policies, a size greater than 5 or 10 mm is the normal accepted result (again depending on risk factors and the demographic).

A good fact sheet can be found on the Centres for Disease Control and Prevention (US) site.