Multiple
Sclerosis (MS)
Epidemiology:
Common sites:
- periventricular (lateral ventricles)
- optic nerves /
chiasm
- brain stem –
ascending and descending tracts
- cerebellum
- spinal cord
Gross features:
- may be superficially
visible at basis pontis or along the spinal
cord
- multiple lesions
in white matter
- may extend into
gray matter
- well-circumscribed,
irregularly shaped plaques
- somewhat depressed
- glassy
- gray-tan
- in fresh state,
plaques are firmer than normal white matter (sclerosis)
Histologic features:
- sharply defined
borders
- active plaque:
- myelin breakdown with relative preservation of
axons
- axon retraction
balls present (eosinophilic balls)
- abundant
macrophages containing lipid-rich, PAS-positive debris
- intracytoplasmic myelin granules
- inflammatory infiltrate
– lymphocytes, monocytes – mostly perivascular cuffs
- depletion of oligodendrocytes
- small lesions
often centred on small vein
- inactive plaque:
- fewer
inflammatory cells and macrophages
- little or no
myelin in centre
- reduction in oligodendrocytes
- astrocytic proliferation and gliosis
- greatly
diminished number of axons
- shadow plaque:
- border not
sharply circumscribed
- thinned-out
myelin sheaths at periphery
Immunophenotype:
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Marker:
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Sensitivity:
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Specificity:
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Molecular features:
- linkage to DR2 haplotype of MHC complex
Other features:
- genetic and
environmental factors
- common clinical
presentations:
- unilateral
vision impairment over a few days
- mildly elevated
protein level in CSF
- oligoclonal bands of gammaglobulins
References: