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All About Acne

Whiteheads, Blackheads and Other Acne Lesions
2009 HowStuffWorks

­Depending on the exact course of events, blockage, infection and inflammation can result in different types of lesions on your ski­n. The two most common are whiteheads and ­blackheads.

­Whiteheads may seem like they appear overnight, but they can actually take up to two months to form before they're visible. Whiteheads form when the pore is totally blocked, and the growing matter has forced the comedo (blockage) to just beneath the surface of the skin.

If there is a plug of cells in the pore and the pore opening expands, so that it's not entirely blocked off, then a blackhead appears. The portion of the comedo­ that is nearest the surface has a concentration of melanin, giving it its appearance and appropriate name.­

If a pore becomes blocked and the wall of the pore collapses and releases the bacteria-ridden clog of skin cells and sebum into the dermis layer of the skin, it leads to other, more severe forms of acne lesions. Among these:

  • Papules. Papules are small (less than half an inch across) bumps that are round and feel somewhat firm to the touch. Papules can get infected if you pick at them or roughly scratch them and open them up.
  • Pustules­. Less-scientific circles commonly refer to pustules as "zits." These are the pus-filled pimples that form in your follicles and sweat glands.
  • Nodules. Nodules are large and hard, existing just beneath the skin. If you set your mind to squeezing or agitating them, they can leave behind elements that may cause the big bump to come back again and again.
  • Suppurative nodules­. Many people call these cysts or boils, and though they resemble and feel like cysts, they're not (cysts have other traits -- such as the ability to contain trapped gases -- and have different causes, like genetics or tumors). These should be examined and treated by a dermatologist.

Now that we know about acne vulgaris in all its forms, we'll learn about other kinds of acne in the next section.