Hi and welcome,
MS isn't actually the only condition that causes 'spinal cord' lesions....
"What Is a Spinal Lesion?
Put simply, a lesion is the name given to an abnormal change which occurs to any tissue or organ, caused by a disease or injury. The abnormal growths of tissue can occur from some form of trauma, including an accident, spinal cord injury, or serious infections, such as syphilis or HIV (Rubin). These tissue abnormalities along the spine can be isolated or supporting tissues may also be damaged. In many cases, any change to cells can be referred to as tumors.
The different kinds of spinal lesions can cause a wide array of dysfunctions — such as motor and sensory deficits. Spinal lesions can be either benign or malignant depending on their severity, location, and if they're caused caused by cancers of the spine such as osteosarcoma or osteochondroma."
A commonn example of an alternative causation of spinal cord lesions would be Transverse Myelitis:
"Transverse myelitis is a neurological disorder caused by inflammation (swelling) across both sides of one level or segment of the spinal cord. Inflammation can damage or destroy myelin, the fatty protective substance that covers nerve cell fibers. This damage causes scars that interrupt the communication between the nerves in the spinal cord and the rest of the body. Most people affected by transverse myelitis will have only one attack; a small percentage may have more than one attack.
Transverse myelitis can appear as the first symptom in conditions such as multiple sclerosis (MS) or neuromyelitis optica (NMO). A person with transverse myelitis who also has an abnormal brain MRI with more than two lesions has an increased chance (as high as 90 percent) of going on to develop MS.
If testing and examination does not suggest a specific cause for the condition, the diagnosis is presumed to be idiopathic transverse myelitis. This is the case in 16-60 percent of people diagnosed with transverse myelitis.
What causes transverse myelitis?
The exact cause of the damage to the spinal cord has not yet been determined with certainty but it is thought that it may be due to an autoimmune reaction to a viral or bacterial infection. In autoimmune diseases, the immune system mistakes the body’s own tissue as foreign, and attacks it, causing inflammation (swelling) that results in damage to the myelin.
An infection precedes the onset of transverse myelitis about 50% of the time.
Transverse myelitis often develops following viral infections such as varicella zoster (the virus that causes chicken pox and shingles), herpes simplex, cytomegalovirus, Epstein-Barr, influenza, echovirus, HIV, hepatitis A, and rubella.
Bacterial skin infections, otitis media (middle-ear infections) and Mycoplasma pneumonia (bacterial pneumonia) have been associated with transverse myelitis.
Some cancers may trigger an abnormal immune response that may lead to transverse myelitis."
Diagnosing MS can be compicated, the MS criteria has changed a little bit over the decades but to meet the basic criteria a person needs to have a minimum of at least one T2 lesion in at least two of the four CNS locations: the juxtacortical, perventricular and infratentorial areas of the brain, and the spinal cord.
I hope that helps........JJ