Comedo

From Infogalactic: the planetary knowledge core
(Redirected from Blackhead)
Jump to: navigation, search

<templatestyles src="Module:Hatnote/styles.css"></templatestyles>

"Blackhead" redirects here. For other uses, see Blackhead (disambiguation).
Blackhead
Blausen 0811 SkinPores.png
Illustration of blackhead
Classification and external resources
Synonyms plural comedones[1]
Specialty Dermatology
ICD-9-CM 706.1
Patient UK Comedo
[[[d:Lua error in Module:Wikidata at line 863: attempt to index field 'wikibase' (a nil value).|edit on Wikidata]]]

A comedo is a clogged hair follicle (pore) in the skin.[2] Keratin (skin debris) combines with oil to block the follicle.[3] A comedo can be open (blackhead) or closed by skin (whitehead), and occur with or without acne.[3] The word comedo comes from the Latin comedere, meaning "to eat up," and was historically used to describe parasitic worms; in modern medical terminology, it is used to suggest the worm-like appearance of the expressed material.[1]

The chronic inflammatory condition that usually includes both comedones and inflamed papules and pustules (pimples) is called acne.[3][4] Infection causes inflammation and the development of pus.[2] Whether or not a skin condition classifies as acne depends on the amount of comedones and infection.[4] Comedones should not be confused with sebaceous filaments.

Comedo-type ductal carcinoma in situ (DCIS) is not related to the skin conditions discussed here. DCIS is a non-invasive form of breast cancer, but comedo-type DCIS may be more aggressive and so may be more likely to become invasive.[5]

Causes

Oil production in the sebaceous glands increases during puberty, causing comedones and acne to be common in teenagers.[3][4] Acne is also found pre-menstrually and in women with polycystic ovarian syndrome.[3] Smoking may worsen acne.[3]

Oxidation rather than poor hygiene or dirt causes blackheads to be black.[2] Washing or scrubbing the skin too much could make it worse, by irritating the skin.[2] Touching and picking at comedones might cause irritation and spread infection.[2] It is not clear what effect shaving has on the development of comedones or acne.[2]

Some, but not all, skin products might increase comedones by blocking pores,[2] and greasy hair products (like pomades) can worsen acne.[3] Skin products that claim to not clog pores may be labeled noncomedogenic or non-acnegenic.[6] Make-up and skin products that are oil-free and water-based may be less likely to cause acne.[6] It is not known whether dietary factors or sun exposure make comedones better, worse or have no effect.[3]

A hair that does not emerge normally can also block the pore and cause a bulge or lead to infection (causing inflammation and pus).[4]

Genes may play a role in the chances of developing acne.[3] Comedones may be more common in some ethnic groups.[3][7] Africans and African-Americans may experience more inflammation in comedones, more comedonal acne, and earlier onset of inflammation.[3][7]

Pathophysiology

Comedones are associated with the pilosebaceous unit, which includes a hair follicle and sebaceous gland. These units are mostly on the face, neck, upper chest, shoulders and back.[3] Excess keratin combined with sebum can plug the opening of the follicle.[3][8] This small plug is called a microcomedo.[8] Androgens increase sebum (oil) production.[3] If sebum continues to build up behind the plug, it can enlarge and form a visible comedo.[8]

A comedo may be open to the air ("blackhead") or closed by skin ("whitehead").[2] Being open to the air causes oxidization, which turns it black.[2] Propionibacterium acnes is the suspected infectious agent in acne.[3] It can proliferate in sebum and cause inflamed pustules (pimples) characteristic of acne.[3] Nodules are inflamed, painful deep bumps under the skin.[3]

Comedones that are 1 mm or larger are called macrocomedones.[9] They are closed comedones and are more frequent on the face than neck.[10]

Solar comedones (sometimes called senile comedones) are related to many years of exposure to the sun, usually on the cheeks, not to acne-related pathophysiology.[11]

Management

Using non-oily cleansers or mild soap may not cause as much irritation to the skin as regular soap.[12][13] Blackheads can be removed across an area with commercially available pore-cleansing strips or the more aggressive cyanoacrylate method used by dermatologists.[14]

Squeezing blackheads and whiteheads can remove them, but it can also damage the skin.[2] Doing so increases the risk of causing or transmitting infection and scarring, as well as potentially pushing any infection deeper into the skin.[2] Comedo extractors are used with careful hygiene in beauty salons and by dermatologists, usually after using steam or warm water.[2]

Complementary medicine options for acne in general have not been shown to be effective in trials.[3] These include aloe vera, pyridoxine (vitamin B6), fruit-derived acids, kampo (Japanese herbal medicine), ayurvedic herbal treatments and acupuncture.[3]

Some acne treatments target infection specifically, but there are treatments that are aimed at the formation of comedones as well.[15] Others remove the dead layers of the skin and may help clear blocked pores.[2][3][4]

Dermatologists can often extract open comedones with minimal skin trauma, but closed comedones are more difficult.[3] Laser treatment for acne might reduce comedones,[16] but dermabrasion and laser therapy have also been known to cause scarring.[9]

Macrocomedones (1 mm or larger) can be removed by a dermatologist using surgical instruments or cauterized with a device that uses light.[9][10] The acne drug isotretinoin can cause severe flare-ups of macrocomedones, so dermatologists recommend removal before starting the drug and during treatment.[9][10]

Some research suggests that the common acne medications, retinoids and azelaic acid, are beneficial and do not cause increased pigmentation of the skin.[17]

Rare conditions

Favre–Racouchot syndrome occurs in sun-damaged skin and includes open and closed comedones.[18]

Nevus comedonicus or comedo nevus is a benign hamartoma (birthmark) of the pilosebaceous unit around the oil-producing gland in the skin.[19] It has widened open hair follicles with dark keratin plugs that resemble comedones, but they are not actually comedones.[19][20]

Dowling-Degos disease is a genetic pigment disorder that includes comedo-like lesions and scars.[21][22]

Familial dyskeratotic comedones is a rare autosomal dominant genetic condition, with keratotic (tough) papules and comedo-like lesions.[23][24]

References

<templatestyles src="Reflist/styles.css" />

Cite error: Invalid <references> tag; parameter "group" is allowed only.

Use <references />, or <references group="..." />
  1. ↑ 1.0 1.1 Lua error in package.lua at line 80: module 'strict' not found.
  2. ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 Lua error in package.lua at line 80: module 'strict' not found.
  3. ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 3.20 Lua error in package.lua at line 80: module 'strict' not found.
  4. ↑ 4.0 4.1 4.2 4.3 4.4 Lua error in package.lua at line 80: module 'strict' not found.
  5. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  6. ↑ 6.0 6.1 Lua error in package.lua at line 80: module 'strict' not found.
  7. ↑ 7.0 7.1 Lua error in package.lua at line 80: module 'strict' not found.
  8. ↑ 8.0 8.1 8.2 Lua error in package.lua at line 80: module 'strict' not found.
  9. ↑ 9.0 9.1 9.2 9.3 Lua error in package.lua at line 80: module 'strict' not found.
  10. ↑ 10.0 10.1 10.2 Lua error in package.lua at line 80: module 'strict' not found.
  11. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  12. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  13. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  14. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  15. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  16. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  17. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  18. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  19. ↑ 19.0 19.1 Lua error in package.lua at line 80: module 'strict' not found.
  20. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  21. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  22. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  23. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  24. ↑ Lua error in package.lua at line 80: module 'strict' not found.
Retrieved from "https://infogalactic.com/w/index.php?title=Comedo&oldid=722290852"