Acne Explained
Sebum produced by the sebaceous gland combines with cells being sloughed off within the hair follicle and "fills up" the hair follicle. When the follicle is "full", the sebum spreads over the skin surface giving the skin an oily appearance. When this process works correctly, the skin is moisturized and remains healthy.
Diagram of a healthy
Follicle
Problems arise when the sebum is trapped in the hair follicle. For reasons that are still unclear, some hair follicles become obstructed.
The sebum is produced but gets trapped on the way out, and the cells that are normally sloughed off become "sticky", plugging up the follicle. The process of obstructing follicles is called comedogenesis. It causes some follicles to form a type of acne called comedones, also known as blackheads and whiteheads.
Diagram of
Blocked Follicle
Non Inflamatory Acne
Comedo (plural comedones)—A comedo is a sebaceous follicle plugged with sebum, dead cells from inside the sebaceous follicle, tiny hairs, and sometimes bacteria.
When a comedo is open, it is commonly called a blackhead because the surface of the plug in the follicle has a blackish appearance.
A closed comedo is commonly called a whitehead; its appearance is that of a skin-colored or slightly inflamed "bump" in the skin.
The whitehead differs in color from the blackhead because the opening of the plugged sebaceous follicle to the skin’s surface is closed or very narrow, in contrast to the distended follicular opening of the blackhead. Neither blackheads nor whiteheads should be squeezed or picked open, unless extracted by a dermatologist under sterile conditions. Tissue injured by squeezing or picking can become infected by staphylococci, streptococci and other skin bacteria.
Diagram and picture of Whitehead Diagram and picture of Blackhead
Inflamatory Acne
Papule—A papule is defined as a small (5 millimeters or less), solid lesion slightly elevated above the surface of the skin. A group of very small papules and microcomedones may be almost invisible but have a "sandpaper" feel to the touch. A papule is caused by localized cellular reaction to the process of acne.
Diagram and
Picture of a
Papule
Pustule—A dome-shaped, fragile lesion containing pus that typically consists of a mixture of white blood cells, dead skin cells, and bacteria. A pustule that forms over a sebaceous follicle usually has a hair in the center. Acne pustules that heal without progressing to cystic form usually leave no scars.
Diagram and
Picture of a
Pustule
Macule—A macule is the temporary red spot left by a healed acne lesion. It is flat, usually red or red-pink, with a well defined border. A macule may persist for days to weeks before disappearing. When a number of macules are present at one time they can contribute to the "inflamed face" appearance of acne.
Nodule—Like a papule, a nodule is a solid, dome-shaped or irregularly-shaped lesion. Unlike a papule, a nodule is characterized by inflammation, extends into deeper layers of the skin and may cause tissue destruction that results in scarring. A nodule may be very painful. Nodular acne is a severe form of acne that may not respond to therapies other than isotretinoin
Please cick on FAQ for answers to the most common questions asked on acne.
