About 40 to 50 million Americans have acne, according to the American Academy of Dermatology. If you have acne, you may notice that not all skin blemishes look the same. Although all acne crops up due to clogged pores on the skin’s surface, blockages may be mild and hardly noticeable or develop into a severe and painful problem.
Basic acne lesions are called microcomedones, which occur when hair follicles become blocked with oil and bacteria starts growing, according to Acne.org. These lesions are referred to as microcomedones because they are invisible to the naked eye, according to HealthcareSouth.com.
Microcomedones transition into non-inflamed blemishes known as comedones. When oil and bacteria stay trapped below the surface of the skin, they are called closed comedones or whiteheads, which are often invisible but may appear as small white spots, according to Acne.org. Whiteheads may ultimately release oil and bacteria to the surface of the skin and heal on their own or they may cause the follicle wall to rupture and result in inflammatory acne.
Blackheads are much like whiteheads in that they are the result of oil and bacteria trapped beneath the skin. Blackheads are simply former whiteheads that have reached the open surface, oxidized and turned a brownish black color in the process, according to Acne.org. Blackheads may last a long time because the oil and bacteria within them drain slowly to the surface of the skin, says Acne.org.
Papules and Pustules
If the follicle wall of a blackhead or whitehead ruptures--sometimes due to a person picking at his blemishes but sometimes at random--white blood cells flood in for healing and cause the pore to become inflamed, according to Acne.org. This event marks the formation of a papule. When those white blood cells eventually work up toward the skin’s surface and become visible, they form what is known a pustule, also called a pimple or a zit, says Acne.org.
Nodules and Cysts
A very deep blockage of a follicle can cause extreme inflammation and result in the most severe form of acne, lesions known as nodules and cysts, according to the American Academy of Dermatology. Nodules and cysts are similar in that they are large and painful, but they differ in that nodules are hard bumps that form deep beneath the surface of the skin and cysts are pus-filled lesions that have the potential to scar, according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases.