Human skin, especially on the face, neck, back, and chest is covered in hundreds of thousands of microscopic hair follicles, often called pores.

For reasons no one completely understands, these follicles sometimes overproduce cells and become blocked. Sebum (oil) which normally drains to the surface gets trapped and bacteria begins to grow.2-11

All acne lesions start out as a microcomedone.1,12-13


Normal follicle

Microcomedone

1. Non-inflammatory acne

Microcomedones can spontaneously become unplugged and heal or they become non-inflamed skin blemishes called comedones--either a whitehead or a blackhead:12-13


whitehead
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Whitehead

When the trapped sebum and bacteria stay below the skin surface, a whitehead is formed. Whiteheads may show up as tiny white spots or they may be so small that they are invisible to the naked eye.1,13
blackhead
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Blackhead

A blackhead occurs when the pore opens to the surface and the sebum, which contains the skin pigment melanin, oxidizes and turns a brown/black color. It is not dirt and can not be washed away. Blackheads can last for a long time because the contents very slowly drain to the surface.1,13

2. Inflammatory acne

A blackhead or whitehead can release its contents to the surface and heal or the follicle wall can rupture and inflammatory acne can ensue. This rupture can be caused by random occurrence or by picking or touching the skin. This is why it is important to leave acne prone skin relatively untouched.1,12-13


papule
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Papule

A papule occurs when there is a break in the follicular wall. White blood cells rush in and the pore becomes inflamed.13
pustule
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Pustule

A pustule forms several days later when white blood cells make their way to the surface of the skin. This is what people usually refer to as a "zit" or a "pimple."13

A papule or pustule can completely collapse or explode, severely inflaming the surrounding skin and may engulf neighboring follicles. These lesions are called cysts or nodules:1,13


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Cyst

Sometimes a severe inflammatory reaction can result in very large pus filled lesions.1,13
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Nodule

When a follicle breaks along the bottom, total collapse can occur, causing a large, inflamed bump that can be sore to the touch.13

Diagrams courtesy of: National Institute of Health

Rare but serious

The following severe forms of acne are rare, but they inflict great hardship to the people who experience them.

acne conglobata

Acne Conglobata

This is the most severe form of acne vulgaris and is more common in males. It is characterized by numerous large lesions, which are sometimes interconnected, along with widespread blackheads. It can cause severe, irrevocable damage to the skin, and disfiguring scarring. It is found on the face, chest, back, buttocks, upper arms, and thighs. The age of onset for acne conglobata is usually between 18 to 30 years, and the condition can stay active for many years. As with all forms of acne, the cause of acne conglobata is unknown. Treatment usually includes isotretinoin (Accutane), and although acne conglobata is sometimes resistant to treatment, it can often be controlled through aggressive treatment over time.14

Acne Fulminans

Acne Fulminans

This is an abrupt onset of acne conglobata-like symptoms which normally afflicts young Caucasian men.14-16 Symptoms of severe nodulocystic, often ulcerating acne are apparent. As with acne conglobata, extreme, disfiguring scarring is common. Acne fulminans is unique in that it also includes a fever and aching of the joints.15 Hospitalization of 3-5 weeks is typical for treatment.16 Acne fulminans does not respond well to antibiotics. Isotretinoin (Accutane) and oral steroids are normally prescribed.

Gram-Negative Folliculitis

Gram-Negative Folliculitis

This condition is a bacterial infection characterized by pustules and cysts, possibly occurring as a complication resulting from a long term antibiotic treatment of acne vulgaris.14 It is a rare condition, and we do not know if it is more common in males or females at this time. Fortunately, isotretinoin (Accutane) is often effective in combating gram-negative folliculitis.

Pyoderma Faciale (Rosacea Fulminans)

Pyoderma Faciale (Rosacea Fulminans)

This type of severe facial acne affects only females, usually between the ages of 20 to 40 years old, and is characterized by large painful nodules, pustules, and sores, all of which may scar.14-15,17 It begins abruptly, and may occur on the skin of a woman who has never had acne before.15-17 It is confined to the face, and usually does not last longer than one year, but can wreak havoc in a very short time. Doctors often prescribe isotretinoin (Accutane) as well as systemic corticosteroids.

  1. "Questions and Answers About Acne." National Institute of Arthritis and Musculoskeletal and Skin Diseases Jan. 2006. National Institutes of Health. 2001.
  2. Kligman AM and Plewig G. Acne and Rosacea. Berlin: Springer, 2000.
  3. Bek-Thomsen M, Lomholt HB and Kilian M. "Acne is not associated with yet-uncultured bacteria." Journal of Clinical Microbiology. (2008); 46(10): 3355-3360.
  4. Zouboulis CC. "Propionibacterium acnes and sebaceous lipogenesis: A love-hate relationship?" Journal of Investigative Dermatology. 2009; 129(9): 2093-2096.
  5. Pappas A, et al. "Sebum analysis of individuals with and without acne." Dermatoendocrinology. 2009; 1(3): 157-161.
  6. Akaza N, et al. "Effects of Propionibacterium acnes on various mRNA expression levels in normal human epidermal keratinocytes in vitro." Journal of Dermatology. 2008; 36(4): 213-223.
  7. Picardo M, et al. "Sebaceous gland lipids." Dermatoendocrinology. 2009; 1(2): 68-71.
  8. Pappas A. "Epidermal surface lipids." Dermatoendocrinology. 1(2): 72-76.
  9. Youn SW. "The role of facial sebum secretion in acne pathogenesis: Facts and controversies." Clinics in Dermatology. 2010; 28(1): 8-11.
  10. Dessinioti C and Katsambas AD. "The role of Propionibacterium acnes in acne pathogenesis: Facts and controversies." Clinics in Dermatology. 2010; 28(1): 2-7.
  11. Makrantonaki E, Ganceviciene R and Zouboulis CC. "An update on the role of the sebaceous gland in the pathogenesis of acne." Dermatoendocrinology. 2011; 3(1): 41-49.
  12. Bettoli V, Layton AM and Thiboutot D. Fast Facts-Acne. Oxford, UK: HealthPress Limited, 2004.
  13. Fry L. The Encyclopedia of Visual Medicine Series: An Atlas of Dermatology. New York: The Parthenon Publishing Group, 1997.
  14. Morelli JG. "Diseases of the neonate." In: Kliegman RM, Behrman RE, Jensen HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, PA: Saunders Elsevier;2007:Chapter 646.
  15. "Questions and Answers About Acne." National Institute of Arthritis and Musculoskeletal and Skin Diseases Jan. 2006. National Institutes of Health. 2001.
  16. Akaza N, et al. "Effects of Propionibacterium acnes on various mRNA expression levels in normal human epidermal keratinocytes in vitro." Journal of Dermatology. 2008; 36(4): 213-223.
  17. Picardo M, et al. "Sebaceous gland lipids." Dermatoendocrinology. 2009; 1(2): 68-71.
  18. Pappas A. "Epidermal surface lipids." Dermatoendocrinology. 1(2): 72-76.