Comedo
Comedo | |
---|---|
Other names | Plural: comedones[1] |
Illustration comparing a normal skin pore with a whitehead and a blackhead | |
Specialty | Dermatology |
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
Some skin products might increase comedones by blocking pores,
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
Comedones are associated with the
A comedo may be open to the air ("blackhead") or closed by skin ("whitehead").
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]
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]
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]
Familial dyskeratotic comedones are a rare autosomal-dominant genetic condition, with keratotic (tough) papules and comedo-like lesions.[24][25]
References
- ^ a b "Comedo". Oxford Dictionary. Oxford University Press. Archived from the original on December 21, 2013. Retrieved 16 June 2013.
- ^ 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.
- ^ S2CID 205962004.
- ^ PMID 21477388.
- PMID 26389187. Retrieved 13 June 2013.
- ^ 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.
- ^ PMID 20725545.
- ^ PMID 17870436.
- ISBN 978-0-323-53113-9.
- ^ PMID 22132254.
- ^ a b c Primary Care Dermatology Society. "Acne: macrocomedones". Clinical Guidance. Primary Care Dermatology Society. Retrieved 12 June 2013.
- ^ DermNetNZ. "Solar comedones". New Zealand Dermatological Society. Retrieved 16 June 2013.
- PMID 12053795.
- S2CID 39430391.
- .
- S2CID 11179291.
- PMID 15199033.
- PMID 23652891.
- ISBN 978-1-4160-2999-1.
- ^ PMID 22863626.
- ^ DermNetNZ. "Comedo Naevus". New Zealand Dermatological Society. Retrieved 16 June 2013.
- PMID 19584468.
- PMID 22225744.
- PMID 15319152.
- ^ OMIM. "Comedones, familial dyskeratotic". OMIM database. OMIM. Archived from the original on 15 June 2013. Retrieved 13 June 2013.
External links
- Rines, George Edwin, ed. (1920). Encyclopedia Americana. .
- What causes blackheads, Treatment and Prevention Archived 2020-01-27 at the Wayback Machine