Pathology of Multiple Sclerosis

Question 1

How does the pathology of large grey lesions look like?

Answer 1

Myelin and oligodendrocyte loss, few/no inflammatory cells, gliotic, and hypocellular.

Question 2

What is a hypercellular rim?

Answer 2

The outer rim of larger lesions will contain foamy macrophages and hypertrophic astrocytes.

Question 3

What are foamy macrophages?

Answer 3

Foam cells are fat-loaden M2 macrophages containing low-density lipoproteins (LDL)

Question 4

How does the pathology of granular lesions look like?

Answer 4

Mostly smaller than the grey ones, and often solid and look exactly like the hypercellular rim of the larger lesions.

Question 5

How do active, chronic active, and inactive lesions differ?

Answer 5

Active lesions are solid and consist of a lot of cells. Chronic active lesions have a hypocellular center and a hypercellular rim. Inactive lesions are entirely hypocellular.

Question 6

How do grey matter lesions look?

Answer 6

There is demyelination but no inflammation, no BBB leakage, and no complement deposition. They are difficult to find with MRI.