Types of Acne

There are many variations of acne / pimples, ranging in severity from mild to severely disfiguring, from comedones (blackheads and whiteheads) to nodules and cysts.

The most common form of acne is known as "acne vulgaris", meaning "common acne." Excessive secretion of oils from the sebaceous glands combines with naturally occurring dead skin cells to block the hair follicles. There also appears to be in some instances a faulty keritinization process in the skin leading to abnormal shedding of skin lining the pores. Oil secretions build up beneath the blocked pore, providing a perfect environment for the skin bacteria Propionibacterium acnes to multiply uncontrolled. In response, the skin inflames, producing the visible lesion.

The typical acne lesions are: comedones, papules, pustules, nodules and inflammatory cysts. These are the more inflamed form of pus-filled or reddish bumps, even boil-like tender swellings. 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.

comedo

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.



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.



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.



Cyst—A cyst is a sac-like lesion containing liquid or semi-liquid material consisting of white blood cells, dead cells, and bacteria. It is larger than a pustule, may be severely inflamed, extends into deeper layers of the skin, may be very painful, and can result in scarring. Cysts and nodules often occur together in a severe form of acne called nodulocystic. This is a severe form of acne that is often resistant to treatment and likely to leave scars after healing.