Comedo

Source: Wikipedia, the free encyclopedia.
(Redirected from
Blackhead
)
Comedo
Other namesPlural: comedones[1]
Illustration comparing a normal skin pore with a whitehead and a blackhead
SpecialtyDermatology

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 comedones, inflamed papules, and pustules (pimples) is called acne.[3][4] Infection causes inflammation and the development of pus.[2] Whether a skin condition classifies as acne depends on the number 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 noninvasive form of breast cancer, but comedo-type DCIS may be more aggressive, so may be more likely to become invasive.[5]

Causes

Oil production in the

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] What effect shaving has on the development of comedones or acne is unclear.[2]

Some skin products might increase comedones by blocking pores,

noncomedogenic or nonacnegenic.[6] Make-up and skin products that are oil-free and water-based may be less likely to cause acne.[6] Whether dietary factors or sun exposure make comedones better, worse, or neither is unknown.[3]

A hair that does not emerge normally, an ingrown hair, 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] People of Latino and recent African descent may experience more inflammation in comedones, more comedonal acne, and earlier onset of inflammation.[3][7]

Pathophysiology

Multiple open comedones at the nasolabial fold and the alar of the nose

Comedones are associated with the

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").

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.[10] They are closed comedones and are more frequent on the face than neck.[11]

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.[12]

Management

Using nonoily cleansers and mild soap may not cause as much irritation to the skin as regular soap.[13][14] Blackheads can be removed across an area with commercially available pore-cleansing strips (which can still damage the skin by leaving the pores wide open and ripping excess skin) or the more aggressive cyanoacrylate method used by dermatologists.[15]

Squeezing blackheads and whiteheads can remove them, but 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]

ayurvedic herbal treatments, and acupuncture.[3]

Some acne treatments target infection specifically, but some treatments are aimed at the formation of comedones, as well.[16] 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,[17] but dermabrasion and laser therapy have also been known to cause scarring.[10]

Macrocomedones (1 mm or larger) can be removed by a dermatologist using surgical instruments or cauterized with a device that uses light.[10][11] The acne drug isotretinoin can cause severe flare-ups of macrocomedones, so dermatologists recommend removal before starting the drug and during treatment.[10][11]

Some research suggests that the common acne medications retinoids and azelaic acid are beneficial and do not cause increased pigmentation of the skin.[18] If using a retinoid, sunscreen is recommended.

Rare conditions

Favre–Racouchot syndrome occurs in sun-damaged skin and includes open and closed comedones.[19]

pilosebaceous unit around the oil-producing gland in the skin.[20] It has widened open hair follicles with dark keratin plugs that resemble comedones, but they are not actually comedones.[20][21]

lesions and scars.[22][23]

Familial dyskeratotic comedones are a rare autosomal-dominant genetic condition, with keratotic (tough) papules and comedo-like lesions.[24][25]

References

  1. ^ a b "Comedo". Oxford Dictionary. Oxford University Press. Archived from the original on December 21, 2013. Retrieved 16 June 2013.
  2. ^ a b c d e f g h i j k l m Informed Health Online. "Acne". Fact sheet. Institute for Quality and Efficiency in Health Care (IQWiG). Retrieved 9 June 2013.
  3. ^
    S2CID 205962004
    .
  4. ^ .
  5. . Retrieved 13 June 2013.
  6. ^ a b British Association of Dermatologists. "Acne". Patient information leaflet. British Association of Dermatologists. Archived from the original on 2013-10-04. Retrieved 12 June 2013.
  7. ^
    PMID 20725545
    .
  8. ^ .
  9. .
  10. ^ .
  11. ^ a b c Primary Care Dermatology Society. "Acne: macrocomedones". Clinical Guidance. Primary Care Dermatology Society. Retrieved 12 June 2013.
  12. ^ DermNetNZ. "Solar comedones". New Zealand Dermatological Society. Retrieved 16 June 2013.
  13. PMID 12053795
    .
  14. .
  15. .
  16. .
  17. .
  18. .
  19. ^ .
  20. ^ DermNetNZ. "Comedo Naevus". New Zealand Dermatological Society. Retrieved 16 June 2013.
  21. PMID 19584468
    .
  22. .
  23. .
  24. ^ OMIM. "Comedones, familial dyskeratotic". OMIM database. OMIM. Archived from the original on 15 June 2013. Retrieved 13 June 2013.

External links