What is Acne?

       The hair follicle is the part of the skin where hair grows. It is attached to the sebaceous gland (oil gland) , which produces sebum that lubricates the hair and prevents the skin from becoming dry. The opening at the surface of the skin, with the attached hair is known as the skin pore. Big pores are associated with big oil glands that produce higher amounts of oil. The oil glands are triggered to produce oil by being exposed to male hormones called androgens. Females also produce androgens at lower quantities via the ovaries or adrenal glands. During puberty, there is a surge of sex hormones and androgens causing the oil glands to pump more oil.

       Acne is a condition of the skin that is caused by excessive oil secretion of the sebaceous glands (oil glands) and the excess production of keratin inside the hair follicles (hyperkertinization). These two conditions cause dead skin cells and excess oil to be trapped inside the pores, this results in pore clogging and the formation of a comedo. Trapped sebum and dead skin cells in the pore are the major food source of the acne-causing bacteria known as Propionibacterium Acnes. The availability of more sebum makes the population of the bacteria grow.

       When the clogged pores are fully closed the comedo has a whitish appearance on the skin surface and is called a whitehead. When the clogged pores are partially opened it is called a blackhead. The partially opened pore allows the slow drainage of sebum, bacteria and dead skin cells on the surface. Blackheads have the characteristic dark color because of the reaction of melanin to oxygen in the surrounding air. Once the bacterial population inside the pore increases at a critical level, the pores become infected often producing pus and breaking out. This type of lesion is called pustule, pimple or zit. It is similar to a whitehead but it has a red base and a yellowish center when you view it from the top.

Severe acne has the following lesions:

Nodules: 

Basically, these are pimples which are bigger than 5mm. They can be painful and grows as large bumps beneath the skin surface. Scarring is very common with this type of lesion. These lesions last for several months.

Cysts: 

These are painful sac-like, pus-filled lesions that may cause scarring. It is similar to a nodule but it is pus-filled and they usually have a diameter of 5mm or more. Do not squeeze cysts as they may cause scarring.

Macule: 

Also known as pseudo scars because they somewhat look like a scar but unlike "true scars" they leave no permanent scar or mark. They are temporary flat, light red or pink spots that have been left from a previously healed lesion. They may last from several days to a few weeks. Sometimes they are raised slightly from the surface of the skin.  

References:

1. http://dermnetnz.org/acne/acne-causes.html "Causes of acne" (Last updated 08 Aug 2007)
2. http://www.acneguide.ca/basics/acne/what_causes_acne.html "What Causes Acne?"(Last modified: Friday, 16-Feb-2007")
3. http://www.nlm.nih.gov/medlineplus/acne.html "Acne" (Topic last reviewed: 13 September 2007)

Last updated: May 18, 2008