I also wonder if just that microglia are activated during chemo. Maybe this is just the most useful case of 'chemo brain' ever.
Based on this, the article suggests that the rituximab Mary was given along with chemo was the key. However, they were unable to test conclusively for antibody evidence of this theory after the fact.
It's certainly an area which can be characterized as rare disease, whether paraneoplastic or otherwise.
There was a phenomenon where sometimes a high fever would cure STDs like syphilis. We generally use antibiotics now that we have them, because they are less dangerous.
And sometimes certain cancers.