I'm sorry to hear that your physician was not able to sufficiently explain your test results.
To start at the beginning, multiple sclerosis
is an immune disease. It targets the sheath that surrounds nerves in your body. You can think of the sheath like the insulation of electrical wiring. Without it, nerve impulses are not conducted properly, and you can temporarily (or permanently) lose motor or sensory abilities. It is classically defined by multiple immune attacks separated in space and time, meaning they happen to different nerves in distinct episodes.
Doctors become concerned when lesions (meaning sites of immune attack against the insulation) crop up quickly, or cause concerning symptoms. Frequently, we find lesions in unexpected locations that have no clinical consequence, meaning they are not appearing quickly and they do not result in any symptoms. This can be the case either because they happened to hit a nerve you weren't using, or the body has already compensated for the attack, and you may or may not have ever noticed symptoms at all. In this case, the lesion was in the thoracic part of your spinal cord (meaning the part of your cord at the level where you have a rib cage).
To summarize, this lesion is a site of immune attack against your nervous system characteristic of your MS, but it probably has not caused any symptoms and has not changed your physician's thinking about your disease. However, a more thorough explanation should be available from your doctor
, and you should ask for clarification at your next visit.