Comedo

Last updated
Comedo
Other namesPlural: comedones [1]
Blausen 0811 SkinPores.png
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 Latin comedere '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]

Contents

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 sebaceous glands increases during puberty, causing comedones and acne to be common in adolescents. [3] [4] Acne is also found premenstrually 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] What effect shaving has on the development of comedones or acne is unclear. [2]

Some skin products might increase comedones by blocking pores, [2] and greasy hair products (such as pomades) can worsen acne. [3] Skin products that claim to not clog pores may be labeled 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 Comedos Nose 01.jpg
Multiple open comedones at the nasolabial fold and the alar of the nose

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 oxidation of the melanin pigment, which turns it black. [9] [2] Cutibacterium 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. [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]

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 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]

Nevus comedonicus or comedo nevus is a benign hamartoma (birthmark) of the 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]

Dowling–Degos disease is a genetic pigment disorder that includes comedo-like 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]

Related Research Articles

<span class="mw-page-title-main">Acne</span> Skin condition characterized by pimples

Acne, also known as acne vulgaris, is a long-term skin condition that occurs when dead skin cells and oil from the skin clog hair follicles. Typical features of the condition include blackheads or whiteheads, pimples, oily skin, and possible scarring. It primarily affects skin with a relatively high number of oil glands, including the face, upper part of the chest, and back. The resulting appearance can lead to lack of confidence, anxiety, reduced self-esteem, and, in extreme cases, depression or thoughts of suicide.

<span class="mw-page-title-main">Isotretinoin</span> Medication primarily used to treat severe acne

Isotretinoin, also known as 13-cis-retinoic acid and sold under the brand name Accutane among others, is a medication used to treat skin diseases like harlequin-type ichthyosis, and lamellar ichthyosis, and severe cystic acne or moderate acne that is unresponsive to antibiotics. Isotretinoin is used off-label to treat basal cell carcinoma and squamous cell carcinoma, although clinical evidence suggests it is not effective in this setting. It is a retinoid, meaning it is related to vitamin A, and is found in small quantities naturally in the body. Its isomer, tretinoin, is also an acne drug.

<span class="mw-page-title-main">Sebaceous hyperplasia</span> Medical condition

Sebaceous hyperplasia is a disorder of the sebaceous glands in which they become enlarged, producing flesh-colored or yellowish, shiny, often umbilicated bumps. Sebaceous hyperplasia, primarily affecting older patients in high-concentration areas like the face, head, and neck, typically has a 2-4 mm diameter and causes no symptoms. The lesions are often surrounded by telangiectatic blood vessels, also known as "crown vessels," and a central dell, which is in line with the origin of the lesions.

<span class="mw-page-title-main">Folliculitis</span> Human and animal disease of follicles

Folliculitis is the infection and inflammation of one or more hair follicles. The condition may occur anywhere on hair-covered skin. The rash may appear as pimples that come to white tips on the face, chest, back, arms, legs, buttocks, or head.

<span class="mw-page-title-main">Sebaceous gland</span> Gland to lubricate the hair and skin

A sebaceous gland or oil gland is a microscopic exocrine gland in the skin that opens into a hair follicle to secrete an oily or waxy matter, called sebum, which lubricates the hair and skin of mammals. In humans, sebaceous glands occur in the greatest number on the face and scalp, but also on all parts of the skin except the palms of the hands and soles of the feet. In the eyelids, meibomian glands, also called tarsal glands, are a type of sebaceous gland that secrete a special type of sebum into tears. Surrounding the female nipples, areolar glands are specialized sebaceous glands for lubricating the nipples. Fordyce spots are benign, visible, sebaceous glands found usually on the lips, gums and inner cheeks, and genitals.

<i>Cutibacterium acnes</i> Species of bacterium

Cutibacterium acnes is the relatively slow-growing, typically aerotolerant anaerobic, gram-positive bacterium (rod) linked to the skin condition of acne; it can also cause chronic blepharitis and endophthalmitis, the latter particularly following intraocular surgery. Its genome has been sequenced and a study has shown several genes can generate enzymes for degrading skin and proteins that may be immunogenic.

<i>Demodex</i> Genus of mites that live on mammals

Demodex is a genus of tiny mites that live in or near hair follicles of mammals. Around 65 species of Demodex are known. Two species live on humans: Demodex folliculorum and Demodex brevis, both frequently referred to as eyelash mites, alternatively face mites or skin mites.

<span class="mw-page-title-main">Keratosis pilaris</span> Skin condition characterized by small bumps caused by overproduction of keratin

Keratosis pilaris is a common, autosomal-dominant, genetic condition of the skin's hair follicles characterized by the appearance of possibly itchy, small, gooseflesh-like bumps, with varying degrees of reddening or inflammation. It most often appears on the outer sides of the upper arms, thighs, face, back, and buttocks; KP can also occur on the hands, and tops of legs, sides, or any body part except glabrous (hairless) skin. Often the lesions can appear on the face, which may be mistaken for acne or folliculitis.

<span class="mw-page-title-main">Sebaceous cyst</span> Types of cyst

A sebaceous cyst is a term commonly used to refer to either:

<i>Demodex folliculorum</i> Species of mite

Demodex folliculorum is a microscopic mite that can survive only on the skin of humans. Most people have D. folliculorum on their skin. Usually, the mites do not cause any harm, so are considered an example of commensalism rather than parasitism; but they can cause disease, known as demodicosis.

<span class="mw-page-title-main">Trichilemmal cyst</span> Common cyst that forms from a hair follicle

A trichilemmal cyst is a common cyst that forms from a hair follicle, most often on the scalp, and is smooth, mobile, and filled with keratin, a protein component found in hair, nails, skin, and horns. Trichilemmal cysts are clinically and histologically distinct from trichilemmal horns, hard tissue that is much rarer and not limited to the scalp. Rarely, these cysts may grow more extensively and form rapidly multiplying trichilemmal tumors, also called proliferating trichilemmal cysts, which are benign, but may grow aggressively at the cyst site. Very rarely, trichilemmal cysts can become cancerous.

<span class="mw-page-title-main">Feline acne</span> Medical condition

Feline acne is a problem seen in cats primarily involving the formation of blackheads accompanied by inflammation on the cat's chin and surrounding areas that can cause lesions, alopecia, and crusty sores. In many cases, symptoms are mild and the disease does not require treatment. Mild cases will resemble dirt on the cat's chin, but the "dirt" will not be brushed off. More severe cases, however, may respond slowly to treatment and seriously detract from the health and appearance of the cat. Feline acne can affect cats of any age, sex, or breed, although Persian cats are also likely to develop acne on the face and in the skin folds. This problem can happen once, reoccur, or even persistent throughout the cat's life.

<span class="mw-page-title-main">Neonatal acne</span> Medical condition

Neonatal acne, also known as acne neonatorum, is a type of acne that develops in newborns, typically before six weeks of life. It presents with open and closed comedones on the cheeks, chin and forehead.

Acne mechanica is an acneiform eruption that has been observed after repetitive physical trauma to the skin such as rubbing, occurring from clothing or sports equipment. In addition to those mechanisms, the skin not getting enough exposure to air also contributes to the formation of acne mechanica. It is often mistaken as a rash that forms on sweaty skin that is constantly being rubbed, but in reality, it is a breakout of acne mechanica. The term "acne" itself describes the occurrence in which hair follicles in the skin get clogged by oil, dead skin cells, dirt and bacteria, or cosmetic products and create a pimple. Pimples can vary in type, size, and shape, but the sole basis of them occurring is the same - the oil gland in the pore becomes clogged and sometimes infected, which creates pus in order to fight the infection and subsequently causes the development of swollen, red lesions on the skin.

Trichostasis spinulosa is a common but rarely diagnosed disorder of the hair follicles that clinically gives the impression of blackheads, but the follicles are filled with funnel-shaped, horny plugs that are bundles of vellus hairs.

<span class="mw-page-title-main">Pimple</span> Type of comedo

A pimple or zit is a kind of comedo that results from excess sebum and dead skin cells getting trapped in the pores of the skin. In its aggravated state, it may evolve into a pustule or papule. Pimples can be treated by acne medications, antibiotics, and anti-inflammatories prescribed by a physician, or various over the counter remedies purchased at a pharmacy.

Infantile acne is a form of acne that begins in very young children. Typical symptoms include inflammatory and noninflammatory lesions, papules and pustules most commonly present on the face. No cause of infantile acne has been established but it may be caused by increased sebaceous gland secretions due to elevated androgens, genetics and the fetal adrenal gland causing increased sebum production. Infantile acne can resolve by itself by age 1 or 2. However, treatment options include topical benzyl peroxide, topical retinoids and topical antibiotics in most cases.

<span class="mw-page-title-main">Favre–Racouchot syndrome</span> Medical condition

Favre–Racouchot syndrome is a solar elastotic disorder consisting of multiple open comedones that occurs in skin damaged by sunlight, especially under and lateral of the eyes. The comedones are widened openings for hair follicles and sebaceous glands filled with material.

<span class="mw-page-title-main">Sebaceous filament</span> Medical condition

A sebaceous filament is a tiny collection of sebum and dead skin cells around a hair follicle, which usually takes the form of a small, yellow to off-white hair-like strand when expressed from the skin.

<span class="mw-page-title-main">Familial disseminated comedones without dyskeratosis</span> Skin disorder from a rare gene mutation

Familial disseminated comedones without dyskeratosis (FDCWD) is a rare autosomal dominant skin disorder characterized by the presence of numerous comedones on the face, trunk, and extremities. The comedones are typically asymptomatic and do not lead to scarring. The disorder is thought to be caused by a mutation in the gene encoding the protein involucrin.

References

  1. 1 2 "Comedo". Oxford Dictionary. Oxford University Press. Archived from the original on December 21, 2013. Retrieved 16 June 2013.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 13 Informed Health Online. "Acne". Fact sheet. Institute for Quality and Efficiency in Health Care (IQWiG). Retrieved 9 June 2013.
  3. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 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.
  4. 1 2 3 4 5 Purdy, Sarah; De Berker, David (2011). "Acne vulgaris". BMJ Clinical Evidence. 2011: 1714. PMC   3275168 . PMID   21477388.
  5. ↑ National Cancer Institute (2002). "Breast cancer treatment". Physician Desk Query. National Cancer Institute. PMID   26389187 . Retrieved 13 June 2013.
  6. 1 2 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. 1 2 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.
  8. 1 2 3 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.
  9. ↑ Kumar, Vinay; Abbas, Abul K.; Aster, Jon C.; Turner, Jerrold R.; Perkins, James A.; Robbins, Stanley L.; Cotran, Ramzi S., eds. (2021). Robbins & Cotran Pathologic Basis of Disease (10th ed.). Philadelphia, PA: Elsevier. p. 1165. ISBN   978-0-323-53113-9.
  10. 1 2 3 4 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.
  11. 1 2 3 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. ↑ Poli, F (Apr 15, 2002). "[Cosmetic treatments and acne]". La Revue du Praticien. 52 (8): 859–62. PMID   12053795.
  14. ↑ 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.
  15. ↑ 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.
  16. ↑ 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.
  17. ↑ 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.
  18. ↑ 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. Lock-green.svg
  19. ↑ 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.
  20. 1 2 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. doi:10.5070/D38XZ7951S. PMID   22863626.
  21. ↑ DermNetNZ. "Comedo Naevus". New Zealand Dermatological Society. Retrieved 16 June 2013.
  22. ↑ 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.
  23. ↑ 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.
  24. ↑ Hallermann, C; Bertsch, HP (Jul–Aug 2004). "Two sisters with familial dyskeratotic comedones". European Journal of Dermatology. 14 (4): 214–5. PMID   15319152.
  25. ↑ OMIM. "Comedones, familial dyskeratotic". OMIM database. OMIM. Archived from the original on 15 June 2013. Retrieved 13 June 2013.
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