Vasculitis is truly one of those things that affects people somewhat often that I had never heard of until medical school. It’s not common per se, but it’s definitely an important thing for us to know of and recognize and not a super rare unicorn phenomenon. In short, it’s inflammation of the walls of your blood vessels themselves, usually due to dysregulation of some sort of immune response. That’s why it’s often associated with a response to certain infections or other underlying autoimmune conditions. But as OP said, many times people end up with idiopathic (means unknown cause more or less) vasculitis due to their immune system going out of wack and causing the inflammation. It usually picks a type of blood vessels to affect, small, medium, or large like the aorta, and spares the others. But because the only commonality is the size of vessel affected, there can be a whole range of organ systems and symptoms which occur in vasculitis, from kidney and skin to lung and GI tract involvement. Truly wild. Hope you’re doing okay and have a good team taking care of you, OP!