Hidradenitis suppurativa can affect one spot or multiple areas of the body. Signs and symptoms of hidradenitis suppurativa include: 1  Blackheads. Small pitted areas of skin containing blackheads â often appearing in pairs or a double-barreled pattern â are a common feature.  Red, tender bumps. These bumps often enlarge, break open and drain pus.
Sebum is an oily substance that's secreted by sebaceous glands to keep skin moisturized. Too much leads to oily skin and too little leads to dry skin. Sebum is an oily substance that's secreted by sebaceous glands to keep skin moisturized.
Human Anatomy Â» Basic Anatomy Â» Sebaceous Glands. Sebaceous glands are microscopic glands in the skin that secrete an oily secretion known as sebum. They are widely distributed all over the dermis of skin, except for the palms and soles. They are especially abundant in the scalp and face.