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.
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.
Hidradenitis suppurativa (HS), sometimes known as acne inversa or Verneuil's disease, is a long-term dermatological condition characterized by the occurrence of inflamed and swollen lumps. These are typically painful and break open, releasing fluid or pus. The areas most commonly affected are the underarms, under the breasts, perineum, buttocks, and the groin. Scar tissue remains after healing. HS may significantly limit many everyday activities, for instance, walking, hugging, moving, and sitting down. Sitting disability may occur in patients with lesions in sacral, gluteal, perineal, femoral, groin or genital regions; and prolonged periods of sitting down can also worsen the condition of the skin of these patients.
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.
Tretinoin, also known as all-trans retinoic acid (ATRA), is a medication used for the treatment of acne and acute promyelocytic leukemia. For acne, it is applied to the skin as a cream, gel or ointment. For acute promyelocytic leukemia, it is effective only when the RARA-PML fusion mutation is present and is taken by mouth for up to three months. Topical tretinoin is also the most extensively investigated retinoid therapy for photoaging.
Benzoyl peroxide is a chemical compound (specifically, an organic peroxide) with structural formula (C6H5−C(=O)O−)2, often abbreviated as (BzO)2. In terms of its structure, the molecule can be described as two benzoyl (C6H5−C(=O)−, Bz) groups connected by a peroxide (−O−O−). It is a white granular solid with a faint odour of benzaldehyde, poorly soluble in water but soluble in acetone, ethanol, and many other organic solvents. Benzoyl peroxide is an oxidizer, which is principally used in the production of polymers.
Adapalene is a third-generation topical retinoid primarily used in the treatment of mild-moderate acne, and is also used off-label to treat keratosis pilaris as well as other skin conditions. Studies have found adapalene is as effective as other retinoids, while causing less irritation. It also has several advantages over other retinoids. The adapalene molecule is more stable compared to tretinoin and tazarotene, which leads to less concern for photodegradation. It is also chemically more stable compared to the other two retinoids, allowing it to be used in combination with benzoyl peroxide. Due to its effects on keratinocyte proliferation and differentiation, adapalene is superior to tretinoin for the treatment of comedonal acne and is often used as a first-line agent. The Swiss company Galderma sells adapalene under the brand name Differin.
A comedo is a clogged hair follicle (pore) in the skin. Keratin 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.
Acne medicamentosa is acne that is caused or aggravated by medication. Because acne is generally a disorder of the pilosebaceous units caused by hormones, the medications that trigger acne medicamentosa most frequently are hormone analogs. It is also often caused by corticosteroids; in this case, it is referred to as steroid acne.
Acneiform eruptions, or acne mimicking eruptions, are a group of skin conditions characterized by small bumps resembling acne. Typically, these bumps are mostly of similar size. Some bumps may be bigger or contain fluid. Generally, blackheads and whiteheads are absent. It tends to appear suddenly, with the chest and back most frequently affected.
Tropical acne is unusually severe acne occurring in the tropics during seasons when the weather is hot and humid.
Steroid acne is an adverse reaction to corticosteroids, and presents as small, firm follicular papules on the forehead, cheeks, and chest. Steroid acne presents with monomorphous pink paupules, as well as comedones, which may be indistinguishable from those of acne vulgaris. Steroid acne is commonly associated with endogenous or exogenous sources of androgen, drug therapy, or diabetes and is less commonly associated with HIV infection or Hodgkin's disease.
Acne conglobata is a highly inflammatory disease presenting with comedones, nodules, abscesses, and draining sinus tracts.
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.
Pomade acne occurs when some of the pomade that is applied to the scalp is also applied to the forehead and is responsible for the development of multiple, closely packed comedones close to the hairline.
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.
Sarecycline, sold under the brand name Seysara, is a narrow-spectrum tetracycline-derived antibiotic medication. It is specifically designed for the treatment of acne, and was approved by the FDA in October 2018 for the treatment of inflammatory lesions of non-nodular moderate to severe acne vulgaris in patients 9 years of age and older. Two randomized and well-controlled clinical trials reported efficacy data on both facial and truncal acne. Efficacy was assessed in a total of 2002 subjects 9 years of age and older. Unlike other tetracycline-class antibiotics, sarecycline has a long C7 moiety that extends into and directly interact with the bacterial messenger RNA (mRNA). The spectrum of activity is limited to clinically relevant Gram-positive bacteria, mainly Cutibacterium acnes, with little or no activity against Gram-negative bacterial microflora commonly found in the human gastrointestinal tract.
Clascoterone, sold under the brand name Winlevi, is an antiandrogen medication which is used topically in the treatment of acne. It is also under development in a higher concentration for the treatment of androgen-dependent scalp hair loss, under the brand name Breezula. The medication is used as a cream by application to the skin, for instance the face and scalp.
