Pathology of multiple sclerosis

Multiple sclerosis (MS) can be pathologically defined as the presence of distributed glial scars (sclerosis or scleroses, in its plural form) in the central nervous system that must show dissemination in time (DIT) and in space (DIS) to be considered MS lesions. Multiple sclerosis (MS) can be pathologically defined as the presence of distributed glial scars (sclerosis or scleroses, in its plural form) in the central nervous system that must show dissemination in time (DIT) and in space (DIS) to be considered MS lesions. The scars that give the name to the condition are produced by the astrocyte cells healing old lesions. These glial scars are the remainings of previous demyelinating inflammatory lesions (encephalomyelitis disseminata) which are produced by one or more unknown underlying conditions. Apart of the disseminated lesions that define the condition, the CNS white matter shows normally other kind of damages. At least five characteristics are present in CNS tissues of MS patients: Inflammation beyond classical white matter lesions (NAWM, NAGM), intrathecal Ig production with oligoclonal bands, an environment fostering immune cell persistence, Follicle-like aggregates in the meninges (B-cells mostly infected with EBV) and a disruption of the blood–brain barrier even outside of active lesions. Confluent subpial cortical lesions are the most specific finding for MS, being exclusively present in MS patients. Though this feature can only be detected during an autopsy there are some subrogate markers under study Damage in MS consists also in areas with hidden damage (normal appearing white and gray matters) and two kinds of cortical lesions: Neuronal loss and cortical demyelinating lesions. The neural loss is the result of neural degeneration from lesions located in the white matter areas and the cortical demyelinating lesions are related to meningeal inflammation. The scars in the white matter are known to appear from confluence of smaller ones Currently the term 'multiple sclerosis' is ambiguous and refers not only to the presence of the scars, but also to the unknown underlying condition that produces these scars. Besides clinical diagnosis uses also the term 'multiple sclerosis' for speaking about the related clinical courses. Therefore, when referring to the presence of the scars is better to use the equivalent term astrocytic fibrillary gliosis. A combination of histologic and/or immunohistochemical stains can be used to visualize post-mortem MS characteristic lesions and to diagnose post-mortem 'inflammatory demyelinating lesions consistent with MS':