In a Tale of Two Cities, What "disfigured human creature in attendance upon Monsigneur"? What does this phrase mean?

you are missing some words. The full quote is "The leprosy of unreality disfigured every human creature in attendance upon Monseigneur."

First, some context. Leprosy is a disease that causes horrible disfigurement, usually in the form of missing extremities. Monsigneur is a famer general, a powerful french noble, who has a large amount of money and influence. At the moment of this phrase, the farmer general is throwing a party.

Dickens is comparing the opulent, unreal lives the nobles lead to a case of leprosy because the wealth and power corrupt these nobles who the farmer general has invited to the party.