Hidradenitis suppurativa (HS), also called inverse acne, may cause nodules and abscesses to develop under the skin. It often affects the armpits and other areas where skin folds occur. HS can ...

"I thought that they were ingrown hairs or acne because I had very bad facial ... until she noticed the same cysts forming under her armpits years later. By the time she was in college, she ...