Unlike a whitehead (a closed comedo), a blackhead is open at the skin's surface (an open comedo).
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"Non-comedogenic" literally means will not block pores, while "comedo" is the medical word for things like blackheads and whiteheads.
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Specifically, numerous and thick tenascin bands were found in the surrounding stroma of comedo DCIS whereas non-comedo DCIS had a single thin tenascin band surrounding them. The difference in these expression patterns implicates Tenascin as a possible factor in the development of the comedo-type morphology in carcinomas.
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Comedo mastitis is a very rare form similar to granulomatous mastitis but with tissue necrosis. Because it is so rare it may be sometimes confused with comedo carcinoma of the breast although the conditions appear to be completely unrelated.
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As of yet, it is still unclear the mechanism by which DCIS of the breast develop into a comedo-type morphology. However, a strong correlation between Tenascin and DCIS nuclear grade has been shown. In a pathological analysis, tenascin was present in all excised tissue from carcinomas. It was found that there were variations in the expression patterns of tenascin in comedo DCIS (comedocarcinoma) versus non-comedo DCIS.
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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.
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A comedo is a clogged hair follicle (pore) in the skin. Keratin (skin debris) combines with oil to block the follicle. A comedo can be open (blackhead) or closed by skin (whitehead) and occur with or without acne. 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.
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Familial dyskeratotic comedones is a rare autosomal dominant genetic condition, with keratotic (tough) papules and comedo-like lesions.
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Limited evidence supports comedo extraction, but it is an option for comedones that do not improve with standard treatment. Another procedure for immediate relief is the injection of a corticosteroid into an inflamed acne comedo. Electrocautery and electrofulguration are effective alternative treatments for comedones. Light therapy is a treatment method that involves delivering certain specific wavelengths of light to an area of skin affected by acne.
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Favre–Racouchot syndrome occurs in sun-damaged skin and includes open and closed comedones. Nevus comedonicus or comedo nevus is a benign hamartoma (birthmark) of the pilosebaceous unit around the oil- producing gland in the skin. It has widened open hair follicles with dark keratin plugs that resemble comedones, but they are not actually comedones. Dowling-Degos disease is a genetic pigment disorder that includes comedo-like lesions and scars.
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A dilated pore, also known as a dilated pore of Winer, is a cutaneous condition characterized by a solitary, prominent, open comedo on the face or upper trunk of an individual.
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The C. acnes biofilm within the hair follicle worsens this process. If the microcomedone is superficial within the hair follicle, the skin pigment melanin is exposed to air, resulting in its oxidation and dark appearance (known as a blackhead or open comedo). In contrast, if the microcomedone occurs deep within the hair follicle, this causes the formation of a whitehead (known as a closed comedo). The main hormonal driver of oily sebum production in the skin is dihydrotestosterone.
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Conditions of sebaceous glands. Sebaceous glands are involved in skin problems such as acne and keratosis pilaris. In the skin pores, sebum and keratin can create a hyperkeratotic plug called a comedo.
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Nevus comedonicus (also known as a "comedo nevus") is characterized by closely arranged, grouped, often linear, slightly elevated papules that have at their center keratinous plugs resembling comedones.James, William; Berger, Timothy; Elston, Dirk (2005). Andrews' Diseases of the Skin: Clinical Dermatology. (10th ed.). Saunders. .
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Androgens increase sebum (oil) production. If sebum continues to build up behind the plug, it can enlarge and form a visible comedo. A comedone may be open to the air ("blackhead") or closed by skin ("whitehead"). Being open to the air causes oxidation, which turns it black.
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Keratosis punctata of the palmar creases is a common skin disorder that occurs most often in black patients, with skin lesions that are 1 to 5mm depressions filled with a comedo-like keratinous plug.James, William; Berger, Timothy; Elston, Dirk (2005). Andrews' Diseases of the Skin: Clinical Dermatology. (10th ed.). Saunders. .
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A pimple 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 papules. 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.
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In addition to nonspecific duct widening the myoepithelial cell layer is atrophic, missing or replaced by fibrous tissue. The original cuboidal epithelial layer may be also severely impaired or missing. Characteristic calcifications are often visible on mammographic images. Periductal mastitis, comedo mastitis, secretory disease of the breast, plasma cell mastitis and mastitis obliterans are sometimes considered special cases or synonyms of duct ectasia syndrome.
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Comedo extraction is a widely used method of treatment for acne vulgaris. A dermatologist or cosmetologist may extract blackheads (open comedones) using gentle pressure around the pore opening, and whiteheads (closed comedones) by incision with a large needle or a blade. If performed skillfully, this treatment may be beneficial to the patient. Possible negative effects of the procedure include incomplete extraction, refilling, scarring and tissue damage.
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Cancer cells within these tumors are highly proliferative. As such, this can result in a lack of sufficient nutrients to some cells; leading to their starvation. As these starved cells die off, a build up of dead cancer cells will begin to form inside the tumor. These groups of necrotic cells are often referred to as comedones, hence the classification of this type of high-grade DCIS as "comedo necrosis".
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Decreased levels of retinoic acid in the skin may contribute to comedo formation. Researchers are investigating methods to increase the skin's production of retinoic acid to address this deficiency. A vaccine against inflammatory acne has shown promising results in mice and humans. Some have voiced concerns about creating a vaccine designed to neutralize a stable community of normal skin bacteria that is known to protect the skin from colonization by more harmful microorganisms.
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Comedo extractors are used with careful hygiene in beauty salons and by dermatologists, usually after using steam or warm water. Complementary medicine options for acne in general have not been shown to be effective in trials. These include aloe vera, pyridoxine (vitamin B6), fruit-derived acids, kampo (Japanese herbal medicine), ayurvedic herbal treatments and acupuncture. Some acne treatments target infection specifically, but there are treatments that are aimed at the formation of comedones as well.
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Activation of TLR2 and TLR4 by C. acnes leads to increased secretion of IL-1α, IL-8, and TNF-α. The release of these inflammatory signals attracts various immune cells to the hair follicle, including neutrophils, macrophages, and Th1 cells. IL-1α stimulates increased skin cell activity and reproduction, which, in turn, fuels comedo development. Furthermore, sebaceous gland cells produce more antimicrobial peptides, such as HBD1 and HBD2, in response to the binding of TLR2 and TLR4.
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Acne is a very common problem, particularly during puberty in teenagers, and is thought to relate to an increased production of sebum due to hormonal factors. The increased production of sebum can lead to a blockage of the sebaceous gland duct. This can cause a comedo, (commonly called a blackhead or a whitehead), which can lead to infection, particularly by the bacteria Cutibacterium acnes. This can inflame the comedones, which then change into the characteristic acne lesions.
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Typically, they first appear in a person's 20s or 30s, and are found in more than 80% of people with the syndrome above the age of 40. The tumors become larger and more numerous over time. Tumors differ between individuals: they may appear merged in plaques, look similar to a comedo with a plug of keratin, or include epidermoid cysts. A large number of tumors on the face can be associated with hyperseborrhea (abnormally elevated sebum production).
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Recommended therapies for first-line use in acne vulgaris treatment include topical retinoids, benzoyl peroxide, and topical or oral antibiotics. Procedures such as light therapy and laser therapy are not first-line treatments and typically have only an add on role due to their high cost and limited evidence. Blue light therapy is of unclear benefit. Medications for acne target the early stages of comedo formation and are generally ineffective for visible skin lesions; acne generally improves between eight and twelve weeks after starting therapy.
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Comedocarcinoma is a kind of breast cancer that demonstrates comedonecrosis, which is the central necrosis of cancer cells within involved ducts. Comedocarcinomas are usually non-infiltrating and intraductal tumors, characterized as a comedo-type, high-grade ductal carcinoma in situ (DCIS). However, there have been accounts of comedocarcinoma which has then diversified into other cell types and developed into infiltrating (invasive) ductal carcinoma. Recurrence and survival rates differ for invasive breast cancer which has originated as comedocarcinoma compared with other types of cancer cells.
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Radiation acne is a cutaneous condition characterized by comedo-like papules occurring at sites of previous exposure to therapeutic ionizing radiation, skin lesions that begin to appear as the acute phase of radiation dermatitis begins to resolve. Radiation recall reactions occur months to years after radiation treatment, a reaction that follows recent administration of a chemotherapeutic agent and occurs with the prior radiation port, characterized by features of radiation dermatitis.Hird AE, Wilson J, Symons S, Sinclair E, Davis M, Chow E. Radiation recall dermatitis: case report and review of the literature. Current Oncology.
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Simplistic representation of the formation of acne comedones. alt=Three images illustrating hair follicle anatomy alt=Image illustrating flowchart of pathophysiology of acne Acne vulgaris is a chronic skin disease of the pilosebaceous unit and develops due to blockages in the skin's hair follicles. These blockages occur as a result of the following four abnormal processes: increased oily sebum production (influenced by androgens), excessive deposition of the protein keratin leading to comedo formation, colonization of the follicle by Cutibacterium acnes (C. acnes) bacteria, and the local release of pro-inflammatory chemicals in the skin.
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Comedocarcinomas are known as the most aggressive form of intraductal carcinomas, although they are considered to be an early stage of breast cancer and are classified as noninvasive. Individuals diagnosed with comedo-type DCIS (comedocarcinoma) often have a higher chance of it developing into an invasive derivative—if left untreated, this chance is nearly 100%. These individuals are also at an increased risk of cancer recurrence, with this recurrence manifesting itself earlier than in other forms of DCIS. The prognosis for comedocarcinoma is usually favorable with treatment intervention (i.e.
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In some cases, DCIS may become invasive and spread to other tissues, but there is no way of determining which lesions will remain stable without treatment, and which will go on to become invasive. DCIS encompasses a wide spectrum of diseases ranging from low-grade lesions that are not life-threatening to high-grade (i.e. potentially highly aggressive) lesions. DCIS has been classified according to the architectural pattern of the cells (solid, cribriform, papillary, and micropapillary), tumor grade (high, intermediate, and low grade), and the presence or absence of comedo histology.
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The term has several meanings on histological and symptomatic levels and on both levels usage overlaps with mastalgia, fibrocystic disease and specific sub- or superclasses of nonpuerperal mastitis. While this is not ideal for a definition it results from actual usage in international literature. Because research literature regarding duct ectasia is anything but abundant it is probably easiest to determine the exact meaning(s) intended by the respective authors on a case by case basis and this section can offer only a few hints. Typical usage in North America is a synonym of nonpuerperal mastitis, including the special cases of granulomatous mastitis, comedo mastitis, subareolar abscess with or without squamous metaplasia of lactiferous ducts and fistulation.
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Another androgenic hormone responsible for increased sebaceous gland activity is DHEA-S. The adrenal glands secrete higher amounts of DHEA-S during adrenarche (a stage of puberty), and this leads to an increase in sebum production. In a sebum-rich skin environment, the naturally occurring and largely commensal skin bacterium C. acnes readily grows and can cause inflammation within and around the follicle due to activation of the innate immune system. C. acnes triggers skin inflammation in acne by increasing the production of several pro-inflammatory chemical signals (such as IL-1α, IL-8, TNF-α, and LTB4); IL-1α is essential to comedo formation. C. acnes' ability to bind and activate a class of immune system receptors known as toll-like receptors (TLRs), especially TLR2 and TLR4, is a core mechanism of acne-related skin inflammation.
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