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.
The outer layer is called the epidermis and the lower level is the dermis. The outer layer (epidermis) produces an oily substance called sebum. You can see this substance when you touch a window or mirror and your oily fingerprint is left there. One job sebum does is it keeps water out of your skin-a job that it does very well.