Possibly just a cyst. Harmless, I gather. My son has one at the side of his nose and the doctor didn't seem unduly bothered. Usually found in younger people than your lady (my son is 30, and that's around the "right" age group). Doctor prescribed a course of antibiotics, which did nothing of course, and when he went back at the end of the course, he just told him that if it didn't worry him just leave it. He could see a cosmetic surgeon and have it removed, but he's a big Wendy when it comes to anything that might be painful, so I think he's going to leave it.