Genetics is thought to be the cause in 80% of cases.The role of diet as a cause is unclear and neither cleanliness nor sunlight appear to be involved.However, cigarette smoking does increase the risk of developing acne, and also worsens its severity. Acne primarily affects skin with a greater number of oil glands, including the face, upper part of the chest, and back.During puberty, in both sexes, acne is often brought on by an increase in androgens such as testosterone. Excessive growth of the bacteria Propionibacterium acnes, which is normally present on the skin, is often involved.
Many treatment options are available to improve the appearance of acne, including lifestyle changes, procedures, and medications. Eating fewer simple carbohydrates like sugar may help. Topical azelaic acid, benzoyl peroxide, and salicylic acid are commonly-used treatments. Antibiotics and retinoids are available in both topical and oral formulations to treat acne. However, resistance to antibiotics may develop.A number of birth control pills may be useful for preventing acne in women. Oral isotretinoin is usually reserved for severe acne due to greater potential side effects. Early and aggressive treatment is advocated by some to lessen the overall long-term impact to individuals.
Acne occurs most commonly during adolescence, affecting an estimated 80–90% of teenagers in the Western world. Lower rates are reported in some rural societies. In 2010, acne was estimated to affect 650 million people globally, making it the 8th most common disease worldwide. People may also be affected before and after puberty.Though it becomes less common in adulthood than in adolescence, nearly half of people in their twenties and thirties continue to have acne. About 4% continue to have difficulties into their forties.
Typical features of acne include seborrhea (increased oil secretion), microcomedones, comedones, papules, pustules, nodules (large papules), and in many cases scarring. The appearance of acne varies with skin color. It may result in psychological and social problems.
Scars
Acne scars are the result of inflammation within the dermal layer of skin, brought on by acne, and are estimated to affect 95% of people with acne vulgaris. The scar is created by an abnormal form of healing following this dermal inflammation. Scarring is most likely to occur with severe nodular acne, but may occur with any form of acne vulgaris. Acne scars are classified based on whether the abnormal healing response following dermal inflammation leads to excess collagen deposition or collagen loss at the site of the acne lesion.
Atrophic acne scars are the most common type of acne scar and have lost collagen from this healing response. Atrophic scars may be further classified as ice-pick scars, boxcar scars, and rolling scars. Ice-pick scars are typically described as narrow (less than 2 mm across), deep scars that extend into the dermis. Boxcar scars are round or ovoid indented scars with sharp borders and vary in size from 1.5–4 mm across.Rolling scars are wider than ice-pick and boxcar scars (4–5 mm across) and have a wave-like pattern of depth in the skin.
Hypertrophic scars are less common, and are characterized by increased collagen content after the abnormal healing response. They are described as firm and raised from the skin.Hypertrophic scars remain within the original margins of the wound, whereas keloid scars can form scar tissue outside of these borders. Keloid scars from acne usually occur in men, and usually occur on the trunk of the body rather than the face.
Pigmentation
Postinflammatory hyperpigmentation (PIH) is usually the result of nodular acne lesions. They often leave behind an inflamed red mark after the original acne lesion has resolved. PIH occurs more often in people with darker skin color. Pigmented scar is a common but misleading term, as it suggests the color change is permanent. Often, PIH can be prevented by avoiding aggravation of the nodule. These scars can fade with time. However, untreated scars can last for months, years, or even be permanent if deeper layers of skin are affected. Daily use of SPF 15 or higher sunscreen can minimize pigmentation associated with acne
CASES
Genetic
The predisposition to acne for specific individuals is likely explained in part by a genetic component, a theory which has been supported by twin studies as well as studies that have looked at rates of acne among first-degree relatives. The genetics of acne susceptibility is likely polygenic, as the disease does not follow a classic Mendelian inheritance pattern. There are multiple candidates for genes which are possibly related to acne, including polymorphisms in TNF-alpha, IL-1 alpha, and CYP1A1, among others.The 308 G/A single nucleotide polymorphism in the gene for tumor necrosis factor (TNF) is associated with acne risk, especially in Caucasian individuals.
Hormonal
Hormonal activity, such as occurs during menstrual cycles and puberty, may contribute to the formation of acne. During puberty, an increase in sex hormones called androgens causes the follicular glands to grow larger and make more sebum. Acne that first develops between the ages of 21 and 25 is uncommon. Several hormones have been linked to acne, including the androgens testosterone, dihydrotestosterone (DHT), and dehydroepiandrosterone sulfate (DHEA-S), as well as insulin-like growth factor 1 (IGF-1) and growth hormone (HGH).
Medical conditions that commonly cause a high-androgen state, such as polycystic ovary syndrome, congenital adrenal hyperplasia, and androgen-secreting tumors, can cause acne in affected individuals. Conversely, people who lack androgenic hormones or are insensitive to the effects of androgens rarely have acne. An increase in androgen (and sebum) synthesis may also be seen during pregnancy. Acne can be a side effect of testosterone replacement therapy or of anabolic steroid use. Anabolic steroids are commonly found in over-the-counter bodybuilding supplements.
Infectious
Propionibacterium acnes (P. acnes) is the anaerobic bacterium species that is widely suspected to contribute to the development of acne, but its exact role in this process is not entirely clear.There are specific sub-strains of P. acnes associated with normal skin and others with moderate or severe inflammatory acne. It is unclear whether these undesirable strains evolve on-site or are acquired, or possibly both depending on the person. These strains have the capability of either changing, perpetuating, or adapting to the abnormal cycle of inflammation, oil production, and inadequate sloughing of dead skin cells from acne pores. One particularly virulent strain has been circulating in Europe for at least 87 years. Infection with the parasitic mite Demodex is associated with the development of acne. However, it is unclear whether eradication of these mites improves acne.
Diet
The relationship between diet and acne is unclear, as there is no high-quality evidence which establishes any definitive link. High-glycemic-load diets have been found to have different degrees of effect on acne severity by different studies. Multiple randomized controlled trials and nonrandomized studies have found a lower-glycemic-load diet to be effective in reducing acne. Additionally, there is weak observational evidence suggesting that dairy milk consumption is positively associated with a higher incidence and severity of acne. Effects from other potentially-contributing dietary factors, such as consumption of chocolate or salt, are not supported by the evidence. Chocolate does contain varying amounts of sugar, which can lead to a high glycemic load, and it can be made with or without milk. There may be a relationship between acne and insulin metabolism, and one trial found a relationship between acne and obesity.Vitamin B12 may trigger skin outbreaks similar to acne (acneiform eruptions), or exacerbate existing acne, when taken in doses exceeding the recommended daily intake.
Smoking
Cigarette smoking is known to increase the risk of developing acne. Additionally, acne severity worsens as the number of cigarettes per day a person smokes increases.
Psychological
Overall, few high-quality studies have been performed which demonstrate that stress causes or worsens acne. While the connection between acne and stress has been debated, some research indicates that increased acne severity is associated with high stress levels in certain settings (e.g., in association with the hormonal changes seen in premenstrual syndrome).There are several features that may indicate that a person's acne vulgaris is sensitive to hormonal influences. Historical and physical clues that may suggest hormone-sensitive acne include onset between ages 20 and 30; worsening the week before a woman's menstrual cycle; acne lesions predominantly over the jawline and chin; and inflammatory/nodular acne lesions.
Several scales exist to grade the severity of acne vulgaris, but no single technique has been universally accepted as the diagnostic standard. Cook's acne grading scale uses photographs to grade severity from 0 to 8 (0 being the least severe and 8 being the most severe). This scale was the first to use a standardized photographic protocol to assess acne severity; since its creation in 1979, Cook's grading scale has undergone several revisions. Leeds acne grading technique counts acne lesions on the face, back, and chest and categorizes them as inflammatory or non-inflammatory. Leeds scores range from 0 (least severe) to 10 (most severe) though modified scales have a maximum score of 12. The Pillsbury acne grading scale simply classifies the severity of the acne from 1 (least severe) to 4 (most severe).
Differential diagnosis
Skin conditions which may mimic acne vulgaris include angiofibromas, folliculitis, keratosis pilaris, perioral dermatitis, and rosacea, among others. Age is one factor which may help a physician distinguish between these disorders. Skin disorders such as perioral dermatitis and keratosis pilaris can appear similar to acne but tend to occur more frequently in childhood, whereas rosacea tends to occur more frequently in older adults. Facial redness triggered by heat or the consumption of alcohol or spicy food is suggestive of rosacea. The presence of comedones can also help health professionals differentiate acne from skin disorders that are similar in appearance.
No comments:
Post a Comment