Stalin's doctors are mentioned to refute the accusation that Stalin was antisemitic. The team of doctors treating him were mostly Jewish, it stayed that way up to his death.

In czarist Russia, doctors (especially Jewish ones) were scapegoated as the reason for royals dying. This was still somewhat true after Stalin's death, but to a lesser extent.

I hope I am remembering that correctly. I'll try to find some page numbers from the Losurdo book

Edit: Chapter "The Question of 'Cosmopolitanism' ", page 229 onwards