Hidradenitis suppurativa (hi-drad-uh-NIE-tis sup-yoo-ruh-TIE-vuh) is a skin condition that causes small, painful lumps to form under the skin. The lumps can break open, or tunnels can form under the skin. The condition mostly affects areas where the skin rubs together, such as the armpits, groin, buttocks and breasts. A chronic skin condition featuring lumps in places such as the armpits or groin. The skin lesions develop as a result of inflammation and infection of sweat glands. This condition features pea- to marble-sized lumps under the skin that can be painful and tend to enlarge and drain pus. They usually occur where skin rubs together, such as in the armpits, groin and buttocks. Medication, corticosteroid injections and sometimes surgery can help manage symptoms.