Acne is a disorder
resulting from the action of hormones on the skin's oil glands (sebaceous
glands), which leads to plugged pores and outbreaks of lesions commonly
called pimples or zits. 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 to people who are affected by the
disorder.
How Does Acne Develop?
Doctors describe acne as
a disease of the pilosebaceous units (PSUs). Found over most of the body,
PSUs consist of a sebaceous gland connected to a canal, called a follicle,
that contains a fine hair. These units are most numerous on the face,
upper back, and chest. The sebaceous glands make an oily substance called
sebum that normally empties onto the skin surface through the opening of
the follicle, commonly called a pore. Cells called keratinocytes line the
follicle.
The hair, sebum, and keratinocytes that fill the narrow
follicle may produce a plug, which is an early sign of acne. The plug
prevents sebum from reaching the surface of the skin through a pore. The
mixture of oil and cells allows bacteria Propionibacterium acnes (P.
acnes) that normally live on the skin to grow in the plugged follicles.
These bacteria produce chemicals and enzymes and attract white blood cells
that cause inflammation. (Inflammation is a characteristic reaction of
tissues to disease or injury and is marked by four signs: swelling,
redness, heat, and pain.) When the wall of the plugged follicle breaks
down, it spills everything into the nearby skin--sebum, shed skin cells,
and bacteria--leading to lesions or pimples.
People with acne
frequently have a variety of lesions, some of which are shown in the
diagrams below. The basic acne lesion, called the comedo (KOM-e-do), is
simply an enlarged and plugged hair follicle. If the plugged follicle, or
comedo, stays beneath the skin, it is called a closed comedo and produces
a white bump called a whitehead. A comedo that reaches the surface of the
skin and opens up is called a blackhead because it looks black on the
skin's surface. This black discoloration is not due to dirt. Both
whiteheads and blackheads may stay in the skin for a long
time.
Other troublesome acne lesions can develop, including the
following:
• Papules: inflamed lesions that usually appear as small,
pink bumps on the skin and can be tender to the touch.
•
Pustules
(pimples): papules topped by pus-filled lesions that may be
red at the base.
• Nodules: large, painful, solid lesions that are lodged
deep within the skin.
• Cysts: deep, painful, pus-filled lesions that can cause
scarring.
Who Gets Acne?
People of all races and
ages get acne. It is most common in adolescents and young adults. Nearly
85 percent of people between the ages of 12 and 24 develop the disorder.
For most people, acne tends to go away by the time they reach their
thirties; however, some people in their forties and fifties continue to
have this skin problem. |
