Comedo

"Blackhead" redirects here. For other uses, see Blackhead (disambiguation).

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][3] Keratin (skin debris) combines with oil to block the follicle.[4] A comedo can be open (blackhead) or closed by skin (whitehead) and occur with or without acne.[4] 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, inflamed papules and pustules (pimples), is called acne.[4][5] Infection causes inflammation and the development of pus.[3] Whether a skin condition classifies as acne depends on the amount of comedones and infection.[5] 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.[6]

## Contents

* 1 Signs and symptoms
* 2 Causes
* 3 Pathophysiology
* 4 Management
* 5 Rare conditions
* 6 See also
* 7 References
* 8 External links

## Signs and symptoms[edit | edit source]

A Comedo is small and flesh-colored with a rough texture. Furthermore are located at skin pore openings[7]

* Plugged follicles forming comedones

* Open comodones

* Multiple closed comedones at the nasolabial fold and the alar of the nose

## Causes[edit | edit source]

Oil production in the sebaceous glands increases during puberty, causing comedones and acne to be common in adolescents.[4][5] Acne is also found premenstrually and in women with polycystic ovarian syndrome.[4] Smoking may worsen acne.[4]

Oxidation rather than poor hygiene or dirt causes blackheads to be black.[3] Washing or scrubbing the skin too much could make it worse, by irritating the skin.[3] Touching and picking at comedones might cause irritation and spread infection.[3] It is not clear what effect shaving has on the development of comedones or acne.[3]

Some, but not all, skin products might increase comedones by blocking pores,[3] and greasy hair products (like pomades) can worsen acne.[4] Skin products that claim to not clog pores may be labeled noncomedogenic or non-acnegenic.[8] Make-up and skin products that are oil-free and water-based may be less likely to cause acne.[8] It is not known whether dietary factors or sun exposure make comedones better, worse or have no effect.[4]

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).[5]

Genes may play a role in the chances of developing acne.[4] Comedones may be more common in some ethnic groups.[4][9] People of Latino and recent African descent may experience more inflammation in comedones, more comedonal acne, and earlier onset of inflammation.[4][9]

## Pathophysiology[edit | edit source]

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.[4] Excess keratin combined with sebum can plug the opening of the follicle.[4][10] This small plug is called a microcomedo.[10] Androgens increase sebum (oil) production.[4] If sebum continues to build up behind the plug, it can enlarge and form a visible comedo.[10]

A comedone may be open to the air ("blackhead") or closed by skin ("whitehead").[3] Being open to the air causes oxidation, which turns it black.[3] Cutibacterium acnes is the suspected infectious agent in acne.[4] It can proliferate in sebum and cause inflamed pustules (pimples) characteristic of acne.[4] Nodules are inflamed, painful deep bumps under the skin.[4]

Comedones that are 1 mm or larger are called macrocomedones.[11] They are closed comedones and are more frequent on the face than neck.[12]

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.[13]

## Management[edit | edit source]

Using non-oily cleansers and mild soap may not cause as much irritation to the skin as regular soap.[14][15] 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.[16]

Squeezing blackheads and whiteheads can remove them, but it can also damage the skin.[3] Doing so increases the risk of causing or transmitting infection and scarring, as well as potentially pushing any infection deeper into the skin.[3] Comedo extractors are used with careful hygiene in beauty salons and by dermatologists, usually after using steam or warm water.[3]

Complementary medicine options for acne in general have not been shown to be effective in trials.[4] These include aloe vera, pyridoxine (vitamin B6), fruit-derived acids, kampo (Japanese herbal medicine), ayurvedic herbal treatments and acupuncture.[4]

Some acne treatments target infection specifically, but there are treatments that are aimed at the formation of comedones as well.[17] Others remove the dead layers of the skin and may help clear blocked pores.[3][4][5]

Dermatologists can often extract open comedones with minimal skin trauma, but closed comedones are more difficult.[4] Laser treatment for acne might reduce comedones,[18] but dermabrasion and laser therapy have also been known to cause scarring.[11]

Macrocomedones (1 mm or larger) can be removed by a dermatologist using surgical instruments or cauterized with a device that uses light.[11][12] The acne drug isotretinoin can cause severe flare-ups of macrocomedones, so dermatologists recommend removal before starting the drug and during treatment.[11][12]

Some research suggests that the common acne medications retinoids and azelaic acid are beneficial and do not cause increased pigmentation of the skin.[19] If using a retinoid, sunscreen is recommended.

## Rare conditions[edit | edit source]

Favre–Racouchot syndrome occurs in sun-damaged skin and includes open and closed comedones.[20]

Nevus comedonicus or comedo nevus is a benign hamartoma (birthmark) of the pilosebaceous unit around the oil-producing gland in the skin.[21] It has widened open hair follicles with dark keratin plugs that resemble comedones, but they are not actually comedones.[21][22]

Dowling-Degos disease is a genetic pigment disorder that includes comedo-like lesions and scars.[23][24]

Familial dyskeratotic comedones is a rare autosomal dominant genetic condition, with keratotic (tough) papules and comedo-like lesions.[25][26]

## See also[edit | edit source]

* List of dermatology terminology

## References[edit | edit source]

1. ↑ 1.0 1.1 "Comedo". Oxford Dictionary. Oxford University Press. Archived from the original on 21 December 2013. Retrieved 16 June 2013.
2. ↑ "Comedonal acne". dermnetnz.org. Archived from the original on 6 February 2022. Retrieved 1 May 2023.
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 Informed Health Online. "Acne". Fact sheet. Institute for Quality and Efficiency in Health Care (IQWiG). Archived from the original on 16 June 2013. Retrieved 9 June 2013.
4. ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 4.18 4.19 4.20 Williams, HC; Dellavalle, RP; Garner, S (Jan 28, 2012). "Acne vulgaris". Lancet. 379 (9813): 361–72. doi:10.1016/S0140-6736(11)60321-8. PMID 21880356. S2CID 205962004.
5. ↑ 5.0 5.1 5.2 5.3 5.4 Purdy, Sarah; De Berker, David (2011). "Acne vulgaris". BMJ Clinical Evidence. 2011: 1714. PMC 3275168. PMID 21477388.
6. ↑ National Cancer Institute. "Breast cancer treatment". Physician Desk Query. National Cancer Institute. Archived from the original on 23 May 2013. Retrieved 13 June 2013.
7. ↑ "Comedones: MedlinePlus Medical Encyclopedia". medlineplus.gov. Archived from the original on 21 April 2021. Retrieved 21 May 2021.
8. ↑ 8.0 8.1 British Association of Dermatologists. "Acne". Patient information leaflet. British Association of Dermatologists. Archived from the original on 2013-10-04. Retrieved 12 June 2013.
9. ↑ 9.0 9.1 Davis, EC; Callender, VD (April 2010). "A review of acne in ethnic skin: pathogenesis, clinical manifestations, and management strategies". The Journal of Clinical and Aesthetic Dermatology. 3 (4): 24–38. PMC 2921746. PMID 20725545.
10. ↑ 10.0 10.1 10.2 Burkhart, CG; Burkhart, CN (October 2007). "Expanding the microcomedone theory and acne therapeutics: Propionibacterium acnes biofilm produces biological glue that holds corneocytes together to form plug". Journal of the American Academy of Dermatology. 57 (4): 722–4. doi:10.1016/j.jaad.2007.05.013. PMID 17870436.
11. ↑ 11.0 11.1 11.2 11.3 Wise, EM; Graber, EM (November 2011). "Clinical pearl: comedone extraction for persistent macrocomedones while on isotretinoin therapy". The Journal of Clinical and Aesthetic Dermatology. 4 (11): 20–1. PMC 3225139. PMID 22132254.
12. ↑ 12.0 12.1 12.2 Primary Care Dermatology Society. "Acne: macrocomedones". Clinical Guidance. Primary Care Dermatology Society. Archived from the original on 10 March 2014. Retrieved 12 June 2013.
13. ↑ DermNetNZ. "Solar comedones". New Zealand Dermatological Society. Archived from the original on 29 May 2013. Retrieved 16 June 2013.
14. ↑ Poli, F (Apr 15, 2002). "[Cosmetic treatments and acne]". La Revue du Praticien. 52 (8): 859–62. PMID 12053795.
15. ↑ Korting, HC; Ponce-Pöschl, E; Klövekorn, W; Schmötzer, G; Arens-Corell, M; Braun-Falco, O (Mar–Apr 1995). "The influence of the regular use of a soap or an acidic syndet bar on pre-acne". Infection. 23 (2): 89–93. doi:10.1007/bf01833872. PMID 7622270. S2CID 39430391.
16. ↑ Pagnoni, A; Kligman, AM; Stoudemayer, T (1999). "Extraction of follicular horny impactions the face by polymers. Efficacy and safety of a cosmetic pore-cleansing strip (Bioré)". Journal of Dermatological Treatment. 10 (1): 47–52. doi:10.3109/09546639909055910.
17. ↑ Gollnick, HP; Krautheim, A (2003). "Topical treatment in acne: current status and future aspects". Dermatology. 206 (1): 29–36. doi:10.1159/000067820. PMID 12566803. S2CID 11179291.
18. ↑ Orringer, JS; Kang, S; Hamilton, T; Schumacher, W; Cho, S; Hammerberg, C; Fisher, GJ; Karimipour, DJ; Johnson, TM; Voorhees, JJ (Jun 16, 2004). "Treatment of acne vulgaris with a pulsed dye laser: a randomized controlled trial". JAMA: The Journal of the American Medical Association. 291 (23): 2834–9. doi:10.1001/jama.291.23.2834. PMID 15199033.
19. ↑ Woolery-Lloyd, HC; Keri, J; Doig, S (Apr 1, 2013). "Retinoids and azelaic Acid to treat acne and hyperpigmentation in skin of color". Journal of Drugs in Dermatology. 12 (4): 434–7. PMID 23652891. Archived from the original on January 21, 2021. Retrieved May 5, 2021.
20. ↑ Rapini, Ronald P.; Bolognia, Jean L.; Jorizzo, Joseph L. (2007). Dermatology: 2-Volume Set. St. Louis: Mosby. p. 1847\. ISBN 978-1-4160-2999-1.
21. ↑ 21.0 21.1 Zarkik, S; Bouhllab, J; Methqal, A; Afifi, Y; Senouci, K; Hassam, B (Jul 15, 2012). "Keratoacanthoma arising in nevus comedonicus". Dermatology Online Journal. 18 (7): 4. PMID 22863626.
22. ↑ DermNetNZ. "Comedo Naevus". New Zealand Dermatological Society. Archived from the original on 21 May 2013. Retrieved 16 June 2013.
23. ↑ Bhagwat, PV; Tophakhane, RS; Shashikumar, BM; Noronha, TM; Naidu, V (Jul–Aug 2009). "Three cases of Dowling Degos disease in two families" (PDF). Indian Journal of Dermatology, Venereology and Leprology. 75 (4): 398–400. doi:10.4103/0378-6323.53139. PMID 19584468. Archived (PDF) from the original on 2018-07-22. Retrieved 2021-05-05.
24. ↑ Khaddar, RK; Mahjoub, WK; Zaraa, I; Sassi, MB; Osman, AB; Debbiche, AC; Mokni, M (January 2012). "[Extensive Dowling-Degos disease following long term PUVA therapy]". Annales de Dermatologie et de Vénéréologie. 139 (1): 54–7. doi:10.1016/j.annder.2011.10.403. PMID 22225744.
25. ↑ Hallermann, C; Bertsch, HP (Jul–Aug 2004). "Two sisters with familial dyskeratotic comedones". European Journal of Dermatology. 14 (4): 214–5. PMID 15319152.
26. ↑ OMIM. "Comedones, familial dyskeratotic". OMIM database. OMIM. Archived from the original on 15 June 2013. Retrieved 13 June 2013.

## External links[edit | edit source]

Classification|

* ICD-9-CM: 706.1

|

* Rines, George Edwin, ed. (1920). "Comedones" . Encyclopedia Americana.

* v
* t
* e

Disorders of skin appendages

Nail|

* thickness: Onychogryphosis
* Onychauxis

* color: Beau's lines
* Yellow nail syndrome
* Leukonychia
* Azure lunula

* shape: Koilonychia
* Nail clubbing

* behavior: Onychotillomania
* Onychophagia

* other: Ingrown nail
* Anonychia

* ungrouped: Paronychia
* Acute
* Chronic
* Chevron nail
* Congenital onychodysplasia of the index fingers
* Green nails
* Half and half nails
* Hangnail
* Hapalonychia
* Hook nail
* Ingrown nail
* Lichen planus of the nails
* Longitudinal erythronychia
* Malalignment of the nail plate
* Median nail dystrophy
* Mees' lines
* Melanonychia
* Muehrcke's lines
* Nail–patella syndrome
* Onychoatrophy
* Onycholysis
* Onychomadesis
* Onychomatricoma
* Onychomycosis
* Onychophosis
* Onychoptosis defluvium
* Onychorrhexis
* Onychoschizia
* Platonychia
* Pincer nails
* Plummer's nail
* Psoriatic nails
* Pterygium inversum unguis
* Pterygium unguis
* Purpura of the nail bed
* Racquet nail
* Red lunulae
* Shell nail syndrome
* Splinter hemorrhage
* Spotted lunulae
* Staining of the nail plate
* Stippled nails
* Subungual hematoma
* Terry's nails
* Twenty-nail dystrophy

Hair|

| Hair loss/
Baldness|

* noncicatricial alopecia: Alopecia
* areata
* totalis
* universalis
* Ophiasis

* Androgenic alopecia (male-pattern baldness)
* Hypotrichosis
* Telogen effluvium
* Traction alopecia
* Lichen planopilaris
* Trichorrhexis nodosa
* Alopecia neoplastica
* Anagen effluvium
* Alopecia mucinosa

* cicatricial alopecia: Pseudopelade of Brocq
* Central centrifugal cicatricial alopecia
* Pressure alopecia
* Traumatic alopecia
* Tumor alopecia
* Hot comb alopecia
* Perifolliculitis capitis abscedens et suffodiens
* Graham-Little syndrome
* Folliculitis decalvans

* ungrouped: Triangular alopecia
* Frontal fibrosing alopecia
* Marie Unna hereditary hypotrichosis

|

Hypertrichosis|

* Hirsutism
* Acquired
* localised
* generalised
* patterned
* Congenital
* generalised
* localised
* X-linked
* Prepubertal

Acneiform
eruption|

| Acne|

* Acne vulgaris
* Acne conglobata
* Acne miliaris necrotica
* Tropical acne
* Infantile acne/Neonatal acne
* Excoriated acne
* Acne fulminans
* Acne medicamentosa (e.g., steroid acne)
* Halogen acne
* Iododerma
* Bromoderma
* Chloracne
* Oil acne
* Tar acne
* Acne cosmetica
* Occupational acne
* Acne aestivalis
* Acne keloidalis nuchae
* Acne mechanica
* Acne with facial edema
* Pomade acne
* Acne necrotica
* Blackhead
* Lupus miliaris disseminatus faciei

|

Rosacea|

* Perioral dermatitis
* Granulomatous perioral dermatitis
* Phymatous rosacea
* Rhinophyma
* Blepharophyma
* Gnathophyma
* Metophyma
* Otophyma
* Papulopustular rosacea
* Lupoid rosacea
* Erythrotelangiectatic rosacea
* Glandular rosacea
* Gram-negative rosacea
* Steroid rosacea
* Ocular rosacea
* Persistent edema of rosacea
* Rosacea conglobata
* variants
* Periorificial dermatitis
* Pyoderma faciale

Ungrouped|

* Granulomatous facial dermatitis
* Idiopathic facial aseptic granuloma
* Periorbital dermatitis
* SAPHO syndrome

Follicular cysts|

* "Sebaceous cyst"
* Epidermoid cyst
* Trichilemmal cyst
* Steatocystoma
* simplex
* multiplex
* Milia

Inflammation|

* Folliculitis
* Folliculitis nares perforans
* Tufted folliculitis
* Pseudofolliculitis barbae

* Hidradenitis
* Hidradenitis suppurativa
* Recurrent palmoplantar hidradenitis
* Neutrophilic eccrine hidradenitis

Ungrouped|

* Acrokeratosis paraneoplastica of Bazex
* Acroosteolysis
* Bubble hair deformity
* Disseminate and recurrent infundibulofolliculitis
* Erosive pustular dermatitis of the scalp
* Erythromelanosis follicularis faciei et colli
* Hair casts
* Hair follicle nevus
* Intermittent hair–follicle dystrophy
* Keratosis pilaris atropicans
* Kinking hair
* Koenen's tumor
* Lichen planopilaris
* Lichen spinulosus
* Loose anagen syndrome
* Menkes kinky hair syndrome
* Monilethrix
* Parakeratosis pustulosa
* Pili (Pili annulati
* Pili bifurcati
* Pili multigemini
* Pili pseudoannulati
* Pili torti)
* Pityriasis amiantacea
* Plica neuropathica
* Poliosis
* Rubinstein–Taybi syndrome
* Setleis syndrome
* Traumatic anserine folliculosis
* Trichomegaly
* Trichomycosis axillaris
* Trichorrhexis (Trichorrhexis invaginata
* Trichorrhexis nodosa)
* Trichostasis spinulosa
* Uncombable hair syndrome
* Wooly hair nevus

Sweat
glands|

| Eccrine|

* Miliaria
* Colloid milium
* Miliaria crystalline
* Miliaria profunda
* Miliaria pustulosa
* Miliaria rubra
* Occlusion miliaria
* Postmiliarial hypohidrosis
* Granulosis rubra nasi
* Ross’ syndrome
* Anhidrosis
* Hyperhidrosis
* Generalized
* Gustatory
* Palmoplantar

|

Apocrine|

* Body odor
* Chromhidrosis
* Fox–Fordyce disease

Sebaceous|

* Sebaceous hyperplasia

* What causes blackheads, Treatment and Prevention Archived 2020-01-27 at the Wayback Machine

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