Did they say why they may have ruled out Multiple Sclerosis?
https://www.google.com/search?q=does+ms+cause+lesions+on+the+spine&rlz=1C1CHBF_enUS1002US1002&oq=does+ms+cause+lesions+on+the+spine&aqs=chrome..69i57j0i22i30l2j0i390l2.7622j0j7&sourceid=chrome&ie=UTF-8
Since myelin coats the nerve fibers that travel through both the brain and the spinal cord, demyelination creates lesions in both areas. This means that if someone with MS has brain lesions, they are also likely to have spinal lesions as well. Spinal cord lesions are common in MS.

THEN THIS:
Multiple sclerosis (MS) causes damage, called lesions, to parts of the central nervous system. MS is a neurological disease. It causes the immune system to attack and destroy myelin — protective fatty tissue that surrounds nerve cells. This process, called demyelination, forms lesions in areas of the central nervous system, including parts of the brain and spinal cord.

This article reviews the link between multiple sclerosis and spinal lesions.
https://www.medicalnewstoday.com/articles/ms-lesions-on-spine