Acne (acne vulgaris, common acne) is a condition that occurs when the oil-secreting glands in the skin are clogged and become inflamed or infected. It is a skin disease that involves the oil glands at the base of hair follicles and typically appears on face, neck, chest, back and shoulders. These areas of skin have the most oil (sebaceous) glands. Acne occurs when hair follicles become plugged with oil and dead skin cells.
No one factor causes acne. Acne occurs when sebaceous (oil) glands attached to the hair follicles are stimulated specially at the time of puberty. Associated with increased oil production is a change in the manner in which the skin cells mature, predisposing them to plug the follicular pore.
The plug can appear as a ‘whitehead’ if it is covered by a thin layer of skin, or if exposed to the air, the darker exposed portion of the plug is called a ‘blackhead.’ The plugged hair follicle gradually enlarges, producing a bump. As the follicle enlarges, the wall may rupture, allowing irritating substances and normal skin bacteria access into the deeper layers of the skin, ultimately producing inflammation. Inflammation near the skin’s surface produces a pustule; deeper inflammation results in a papule (pimple); if the inflammation is deeper still, it forms a cyst.