Acne occurs often in adolescents and can persist into adulthood.
As the oil producing ducts of the skin increase production, the actual oil duct becomes clogged. The ducts may then burst and become irritated and infected. Plugged oil ducts appear in two different types. A blackhead, or open dome, is exposed to the air, causing the surface secretions of the ducts to become pigmented or darker in color. A whitehead, or closed dome, is not open to the air, so there is no color change.