Help with creating and maintaining private health records . Get all this and more now, free . Acne lesions usually occur on the face, neck, back, chest, and shoulders. Nearly 17 million people in the United States have acne, making it the most common skin disease. Although acne is not a serious health threat, severe acne can lead to disfiguring, permanent scarring, which can be upsetting for people who suffer from the disorder.
Doctors describe acne as a disease of the pilosebaceous units.
These units are largest and most numerous on the face, upper back, and chest-areas where acne tends to occur. The sebaceous glands make an oily substance called sebum that normally empties onto the skin surface through the opening of the follicle. Acne is believed to result from a change in the inner lining of the follicle that prevents the sebum from passing through. For reasons not understood, cells from the lining of the follicle are shed too fast and clump together. The clumped cells plug up the follicle's opening so sebum cannot reach the surface of the skin.