In the book brave new world what does lupus mean?

lupus is like a skin disease, i am sure it was mentioned first in chapter 1

HOWEVER NOBODY actually has the disease. It was only mentioned because the character was in a room lit with only red light, therefore giving her the appearance of having lupus, whose trademark symptom is reddened, rashy skin. There, now when someone says "pneumatic" in that book you don't have to cringe at the image that enters your mind.