Mom tested positive for TB twice, but X-ray didn't find anything. What are the possible outcomes of this?

Thank you all for your input and helping me to become better educated. I know treatments are so different from years ago when her father died of TB. We're going to an infectious diseases doctor on Thurs, so hopefully will find out something more definite about what's going on with her and what can be done.

I beg to differ with most of the explanations here.While TB is primarily a lung disease it can infect other parts of the body. The skin test can show positive while the lungs are shown as clear.
Example: My wife had renal tuberculosis and nearly lost her kidney functions. Her lungs were clear but the recurring urinary infection led one DR to suspect something else.

He referred her to urology . Over fifty percent of her kidneys were full of those little TB critters. Two years of intense treatment cleared things up. Lots of pills each day for two years and frequent visits to the Urologist for kidney xrays with the dye.

Now it is dementia and no treatment available.
I don't know what the treatment is today but when I reacted positive to the skin test I was put a drug called INH for one year and no retest. I was advised to only have chest xrays.
I am not trying to diagnose anything here just sharing my own experience.

A positive result means your mom, somewhere along the line, has been EXPOSED to TB. It does not mean she HAS TB.

Usually a skin test is done. It's positive if there is a red, raised "bump" at the injection site.  A positive test will be positive for life. From then on, the doctor orders a chest X-Ray. It is the only way to test for active disease.

Then a chest X-Ray, at intervals, will prove the existence (or not) of the disease. If it develops into TB, there is medication for it.

Just remember, being positive doesn't mean you have ACTIVE tuberculosis.

My dad became positive after living in two or three board and care homes. He never developed active TB.
As a nurse, I've taken care of active TB patients and I test negative.

In our hospital we employees have to get a TB test every year. If the skin test is positive, you get a chest Xray. If it is clear you are good to go! So many employees are from other countries that have TB , that they fail the skin test. When dad went into MC they only wanted the Xray.. not the skin test because of this. You may have nothing to worry about.

Bookish, what does your Mom's doctor have to say about this TB? One would think if the TB didn't show up on a chest x-ray that maybe this is a latent TB infection, and Mom may need to take medicine to keep from developing active TB disease.