Acne Vulgaris is an inflammatory
disease of the skin, caused by changes in the pilosebaceous units (skin structures consisting of a hair follicle and its associated
sebaceous gland). Acne lesions are commonly referred to as pimples, spots, or "zits".
Acne develops
because of impairments of the functioning of skin glands (dermis and epidermis), notably blocked follicles.
Acne is a highly complicated and variable form of skin infection. It is most common during adolescence, affecting more than
85% of teenagers, but not infrequently also continues into adulthood.
For most people, acne diminishes over
time and tends to disappear, or at least decrease, after one reaches his or her early twenties. There is, however, no way
to predict how long it will take for it to disappear entirely, and some individuals will continue to suffer from acne decades
later, into their thirties and forties and even beyond.
The fine structure of the dermis is very intricate,
with dozens of specialized cells, sweat glands, oil glands, nerves and capillaries. it is subject to malformation, damage,
and infection. Some sebaceous glands grow deformed without a drainage channel through the skin.
Others swell
by up to 20 times their original size. When these are drained, the walls of the enlarged gland are still intact under the
skin and free to accumulate sebum and may or may not become infected. Sometimes a pustule forms around a hair strand that
has not reached the surface and that has grown more than a centimetre curled inside the sebaceous gland.
The
most common form of acne is known as "acne vulgaris", meaning "common acne." Many teenagers get this type
of acne. Excessive secretion of oils from the sebaceous glands accompanies the plugging of the pores with naturally occurring
dead skin cells (corneocytes) blocking hair follicles.
The accumulation of these corneocytes in the duct
appears to be due to a failure of the normal keratinization process in the skin which usually leads to shedding of skin cells
lining the pores.
Oil secretions are said to build up beneath the blocked pore, providing a perfect environment
for the skin bacteria Propionibacterium acnes and the lipophilic (oil/lipid-loving) yeast Malassezia to multiply uncontrollably.
Under the microscope, however, there is no evidence of pooled trapped sebum. The oil percolates through
the plugged duct onto the surface.
In response to the bacterial and yeast populations, the skin inflames,
producing the visible lesion.
The face and upper neck are the most commonly affected, but the chest, back
and shoulders may have acne as well. The upper arms can also have acne, but lesions found there are often keratosis pilaris,
not acne.
The typical acne lesions are: comedones, papules, pustules, nodules and inflammatory cysts known
as cystic acne, one of the more severe forms.
These are more inflamed and pus-filled or reddish bumps, that
can easily lead to scarring or serious infections. Non-inflamed 'sebaceous cysts', more properly called epidermoid
cysts, occur either in association with acne or alone but are not a constant feature. After resolution of acne lesions, prominent
unsightly scars may remain.
Aside from scarring, its main effects are psychological, such as reduced self-esteem
and, according to at least one study, depression or suicide.
Acne usually appears during adolescence, when
people already tend to be most socially insecure. Early and aggressive treatment is therefore advocated to lessen the overall
impact to individuals.
There are many misconceptions and myths about acne. Exactly why some people get acne
and some do not is not fully known. It is known to be partly hereditary. Several factors are known to be linked to acne:
* Family history
* Hormonal activity, such as menstrual cycles and puberty
* Stress, through
increased output of hormones from the adrenal(stress) glands.
* Hyperactive sebaceous glands, secondary to the
three hormone sources above.
* Accumulation of dead skin cells.
* Bacteria in the pores, to which the
body becomes 'allergic'.
* Skin irritation or scratching of any sort will activate inflammation.
* Use of anabolic steroids.
* Any medication containing halogens (iodides, chlorides, bromides), lithium, barbiturates,
or androgens.
* Exposure to high levels of chlorine compounds, particularly chlorinated dioxins, can cause severe,
long-lasting acne, known as Chloracne.
Traditionally, attention has focused mostly on hormone-driven over-production
of sebum as the main contributing factor of acne.
More recently, more attention has been given to narrowing of
the follicle channel as a second main contributing factor.
Abnormal shedding of the cells lining the follicle,
abnormal cell binding ("hyperkeratinization") within the follicle, and water retention in the skin (swelling the
skin and so pressing the follicles shut) have all been put forward as important mechanisms.
Several hormones
have been linked to acne: the male hormones testosterone, dihydrotestosterone (DHT) and dehydroepiandrosterone sulfate (DHEAS),
as well as insulin-like growth factor 1 (IGF-I).
In addition, acne-prone skin has been shown to be insulin
resistant. |
