What is acne?

Causes and Symptoms

Many skin disorders are grouped together as acne. The two most common are acne vulgaris and acne rosacea. Other acne diseases include neonatal acne and infantile acne, seen respectively in newborn babies and infants. Drug acne is a consequence of the administration of such medications as corticosteroids, iodides, bromides, anticonvulsants, lithium preparations, and oral contraceptives, to name some of the more common agents that are sometimes involved in acne outbreaks. Pomade acne and acne cosmetica are associated with the use of greasy or sensitizing substances on the skin, such as hair oil, suntan lotions, cosmetics, soap, and shampoo. They may be the sole cause of acne in some individuals or may aggravate existing outbreaks of acne vulgaris. Occupational acne, as the name implies, is associated with exposure to skin irritants in the workplace. Chemicals, waxes, greases, and other substances may be involved. Acné excoriée des jeunes filles, or acne in young girls, is thought to be associated with emotional distress. In spite of the name, it can occur in boys as well. Two forms of acne are seen in young women. One is pyoderma faciale, a skin eruption that always occurs
on the face. The other is perioral dermatitis (peri, around; ora, the mouth), characterized by redness, pimples, and pustules. Acne conglobata is a rare but severe skin disorder that is seen in men between the ages of eighteen and thirty.

In acne vulgaris, a disruption occurs in the normal activity of the pilosebaceous units of the dermis, the layer of the skin that contains the blood vessels, nerves and nerve endings, glands, and hair follicles. Ordinarily, the sebaceous glands secrete sebum into the hair follicles, where it travels up hair shafts and onto the outer surface of the skin, to maintain proper hydration of the hair and skin and prevent loss of moisture. In acne vulgaris, the amount of sebum increases greatly, and the hair shaft that allows it to escape becomes plugged, holding in the sebum.

Acne vulgaris usually occurs during
puberty and is the result of some of the hormones released at that time to help the child become an adult. One of the major hormones is testosterone, an androgen (andros, man or manhood; gen, generating or causing), so called because it brings about bodily changes that convert a boy into a man. In boys, testosterone and other male hormones cause sexual organs to mature. Hair begins to grow on the chest and face and in pubic areas and armpits. Musculature is increased, and the larynx (voice box) is enlarged, so the voice deepens. In males, testosterone and other male hormones are produced primarily in the testicles. In girls, estrogens and other female hormones are released during puberty, directing the passage of the child from girlhood to womanhood. Testosterone is also produced, mostly in the ovaries and the adrenal glands.

In both sexes during puberty, testosterone is taken up by the pilosebaceous glands and converted to dihydrotestosterone, a substance that causes an increase in the size of the glands and increased secretion of the fatty substance sebum into hair follicles. At the same time, a process occurs that closes off the hair follicle, allowing sebum, keratin, and other matter to collect. This process is called intrafollicular hyperkeratosis (from intra, inside, follicular, referring to the follicle, hyper, excessive, and keratosis, production of keratin). Keratin buildup creates a plug that blocks the follicle opening and permits the accumulation of sebum, causing the formation of a closed comedo. As more and more material collects, the comedo becomes visible as a white-capped pimple, or whitehead. Closed comedones are the precursors of the papules, pustules, nodules, and cysts characteristic of acne vulgaris. Papula means “pimple,” a pustule is a pimple containing pus, nodus means a
small knot, and the word “cyst” comes from kystis, meaning “bladder,” or in this case a sac filled with semisolid material. Sometimes cysts are referred to generically as sebaceous cysts, but the material inside is usually keratin.

Another lesion in acne vulgaris, called an open comedo, occurs when a sac in the outer layer of the skin fills with keratin, sebum, and other matter. Unlike the closed comedo, it is open to the surface of the skin and the material inside appears black—hence the term “blackhead.” Blackheads are unsightly, make the skin look dirty, and suggest that they are caused by bad hygienic habits. This is not true, but exactly why the material in the sac turns black is not fully understood. Some believe that the natural skin pigment melanin is involved.

Blackheads are usually easily managed and rarely become inflamed. It is the closed comedo, or whitehead, that causes the disfiguring lesions of acne vulgaris. As the closed comedo fills with keratin and sebum, colonies of bacteria, usually Propionibacterium acnes, develop at the site. The bacteria secrete enzymes that break down the sebum, forming free fatty acids that inflame and irritate the follicle wall. With inflammation, white blood cells are drawn to the area to fight off the bacteria.

The comedo enlarges with further accumulation of white blood cells, keratin, and sebum until the follicle wall ruptures, spreading inflammation. If the inflammation is close to the surface of the skin, the lesion will usually be a pustule. If the inflammation is deeper, a larger papule, nodule, or cyst may form.

Clothing, cosmetics, and other factors may exacerbate acne vulgaris. Headbands, chin straps, and other items can cause trauma that ruptures closed comedones and spreads infection. Ingredients in cosmetics, soaps, and other preparations used on the skin can contribute to the formation of comedones in acne vulgaris. Lanolin, petrolatum, laurel alcohol, and oleic acid are among the chemicals commonly found in skin creams, cosmetics, soaps, shampoos, and other preparations applied to the skin. They have been shown to aggravate existing acne in some people and to bring on acne eruptions in others.

It was long thought that fatty foods—such as chocolate, ice cream, desserts, and peanut butter—contributed to acne, perhaps because teenagers eat so much of them. This theory has been largely discarded. Except for specific allergic sensitivities, foods do not appear to cause or in any other way affect the eruptions of acne vulgaris.

Cases of acne vulgaris are classified as mild, moderate, or severe. In mild and moderate acne vulgaris, the number of lesions ranges from a few to many, appearing regularly or sporadically and occurring mostly in the top layer of the skin. Consequently, these cases are sometimes called “superficial acne.” In severe cases, the acne lesions are deep, extending down into the skin, and characterized by inflamed papules and pustules.

Superficial acne, or mild-to-moderate acne vulgaris, is easily managed with the therapies available. The teenager goes through a year to two dealing with “zits.” The problem may be irritating and may cause inconvenience and discomfort, but it is common among teenagers, and little lasting harm is done. With time and treatment, the skin clears and the problem is over.

With deep or severe acne, however, the condition can be devastating, physically and psychologically. In these cases, the lesions may come in massive eruptions that cover the face and extend to the neck, chest, and back. The lesions can be large and deep, frequently causing disfiguring pits and craters that become lifelong scars. The victims of severe acne can suffer profound psychological damage. The disease strikes at a time when most teenagers are especially concerned with being gregarious, popular, and well liked. The chronic, constant disfigurement effectively isolates the individual, however, often making him or her unwilling to risk social contact.

The other common form of acne is acne rosacea, so called because of the “rosy” color that appears on the face. Unlike acne vulgaris, it rarely strikes people under thirty years of age and is not characterized by comedones, although papules and pustules are common. It is predominantly seen in women, although its most serious manifestations are seen in men. The cause of acne rosacea is unknown, but it is more likely to strike people with fair complexions. It is usually limited to the center of the face, but eruptions may occur on other parts of the body.

Acne rosacea is progressive; that is, it gets worse as the patient grows older. It seems to occur most often in people who have a tendency to redden or blush easily. The blushing, whether it is caused by emotional distress, such as shame or embarrassment, or by heat, food, or drink, may be the precursor of acne rosacea. The individual finds that episodes of blushing last longer and longer until, eventually, the redness becomes permanent. Papules and pustules break out, and surface blood vessels become dilated, causing further redness. As the disease progresses, tissue overgrowth may cause the nose to swell and become red and bulbous. Inflammation may develop in and around the eyes and threaten vision. These severe symptoms occur more often in men than in women.

Treatment and Therapy

The majority of acne patients are treated at home with over-the-counter preparations applied topically (that is, on the skin). For years, many of the agents recommended for acne contained sulfur, and some still do. Sulfur is useful for reducing comedones, but it has been suggested that sulfur by itself may also cause comedones; however, sulfur compounds, such as zinc sulfate, are not suspected of causing comedones. Resorcinol and salicylic acid are commonly included in topical over-the-counter preparations to promote scaling and reduce comedones. Sometimes sulfur, resorcinol, and salicylic acid are used singly, sometimes together, and sometimes combined with topical antiseptics or other agents.

While most patients will be helped by the available over-the-counter agents, many will not respond adequately to such home therapy. These patients must be seen by a doctor, such as a family practitioner or dermatologist. The physician attempts to eliminate existing lesions, prevent the formation of new lesions, destroy microorganisms, relieve inflammation, and prevent the occurrence of cysts, papules, and pustules. If the patient’s skin is oily, the physician may advise washing the face and other affected areas several times a day. This has little effect on the development of comedones, but it may improve the patient’s appearance and self-esteem. The physician will also use medications that are similar to over-the-counter antiacne agents but more powerful. These include drying agents, topical antibiotic preparations, and agents to abrade the skin, such as exfoliants or desquamating (scale-removing) agents.

Various topical antibiotics have been developed for use in acne vulgaris, such as topical tetracycline, clindamycin, and erythromycin. One that is often used is benzoyl peroxide, a topical antibiotic that can penetrate the skin and reach the sites of infection in the hair follicles. It is also a powerful irritant that increases the growth rate of epithelial cells and promotes sloughing, which helps clear the surface of the skin. It is effective in resolving comedones and seems to suppress the release of sebum. Because it has a high potential for skin irritation, benzoyl peroxide must be used carefully. Physicians generally start with the weaker formulations of the drug and increase the strength as tolerance develops.

Vitamin A has been given orally to patients with acne vulgaris in the hope of preventing the formation of comedones. The effective oral dose of the vitamin for this purpose is so high, however, that it could be toxic. Therefore, a topical form of vitamin A was developed called vitamin A acid, retinoic acid, or tretinoin (marketed as Retin A). Applied directly to the skin, it has proved highly beneficial in the treatment of acne vulgaris. It clears comedones from the hair follicles and suppresses the formation of new comedones. It reduces inflammation and facilitates the transdermal (through-the-skin) penetration of medications such as benzoyl peroxide and other topical antibiotics. Like benzoyl peroxide, vitamin A acid can be irritating to the skin, so it must be used carefully. When benzoyl peroxide and vitamin A acid are used in combination in the treatment of acne vulgaris, their therapeutic effectiveness is significantly increased. The physician generally prescribes a morning application of one and an evening application of the other.

When large comedones, pustules, or cysts form, the physician may elect to remove them surgically. The procedure is quite effective in improving appearance, but it does nothing to affect the course of the disease. Furthermore, it demands great skill on the part of the physician to avoid causing damage and irritating the surrounding skin, rupturing the comedo wall, and allowing inflammation to spread. The patient should be advised not to try to duplicate the process at home: Picking at pimples could create open lesions that may take weeks to heal and may produce deep scars. Sometimes, the physician will insert a needle into a deep lesion in order to drain the material from it. Sometimes, the physician tries to avoid surgery by injecting a minute quantity of corticosteroid, such as triamcinolone acetonide, into a deep lesion to reduce its size.

The physician may wish to add the benefits of sunlight to medical therapy. Sunlight helps dry the skin and promotes scaling and clearing of the skin, which is probably why acne improves in summer. The physician may suggest sunbathing, but an overzealous patient could become sunburned or chronically overexposed to the sun, thereby risking skin cancer. The beneficial effects of natural sunlight are not necessarily achievable with a sunlamp and, over a long period of exposure, the ultraviolet light produced by some lamps may actually increase sebum production and promote intrafollicular hyperkeratosis.

About 12 percent of patients with acne vulgaris develop severe or deep acne. In devising a treatment regime for these cases, the physician has many options to help clear the patient’s skin, reduce the number and occurrence of lesions, and prevent the scarring that can disfigure the patient for life. Both the topical medications benzoyl peroxide and vitamin A acid are used, singly and in combination, as well as many other topical preparations. Nevertheless, these patients often also require oral antibiotics to fight their infection from within.

It may take weeks for oral antibiotic therapy to achieve results, and it may even be necessary for the patient to continue the therapy for years. Therefore, the physician looks for an antibiotic that is effective and safe for long-term use. Oral tetracycline is often the physician’s choice because it has been proven effective against Propionibacterium acnes, and it seems to suppress the formation of comedones. Oral tetracycline is usually safe for long-term therapy, and it is economical. Other oral antibiotics used to treat acne vulgaris are erythromycin, clindamycin, and minocycline.

Yet in long-term therapy with any broad-spectrum antibiotic, there is always the possibility that the agent being used will not only kill the offending organism but also destroy “friendly” bacteria that aid in bodily processes and help protect the body from other microorganisms. When this happens, disease-causing pathogens may be allowed to flourish and cause infection. For example, prolonged use of antibiotics in women may allow the growth of a yeastlike fungus, Candida, which can cause vaginitis. Prolonged use of clindamycin may allow the proliferation of Clostridium difficile, which could result in ulcerative colitis, a severe disorder of the lower gastrointestinal tract.

If, for any reason, the physician believes that oral antibiotics are not working or must be discontinued, there are other therapeutic agents and other procedures that may be helpful in treating severe, deep acne vulgaris. One medication that is highly effective, but also potentially very harmful, is isotretinoin. As the name implies, isotretinoin (meaning “similar to tretinoin”) is derived from vitamin A, but it is both more effective and more difficult to use. Unlike the topical vitamin A acid preparations, isotretinoin is taken orally. It is highly effective in inhibiting the function of sebaceous glands and preventing the formation of closed comedones by reducing keratinization, but isotretinoin also produces a wide range of side effects. The majority of these are skin disorders, but the bones and joints, the eyes, and other organs can be affected. Perhaps the most serious adverse effect of isotretinoin is that it can cause severe abnormalities in the fetuses of pregnant women. Therefore, pregnancy is an absolute contraindication for isotretinoin. Before they take this drug, women of childbearing age are checked to ensure that they are not
pregnant. They are advised to use strict contraceptive measures one month before therapy, during the entire course of therapy, and for at least one month after therapy has been discontinued.

Estrogens, female hormones, have been used to treat severe acne in girls and women who are more than sixteen years of age. The aim of this therapy is to counteract the sebum-stimulating activity of circulating testosterone and to reduce the formation of comedones by reducing the amount of sebum produced. Estrogens cannot be used in males because the dose required to reduce sebum production could produce feminizing side effects.

Persistent lesions can be treated with cryotherapy. In this procedure, an extremely cold substance such as dry ice or liquid nitrogen is carefully applied to the lesion. This technique is effective in reducing both small pustules and deeper cysts. For patients whose skin has been deeply scarred by acne, a procedure called dermabrasion, in which the top layer of skin is removed, may help improve the appearance.

Although its cause is unknown, acne rosacea can be treated. The topical antiparasitic drug metronidazole, applied in a cream, and oral broad-spectrum antibiotics such as tetracycline have been found effective. It may be necessary to continue antibiotic therapy for a long period of time, but the treatment is usually effective. Surgery may be required to correct the bulbous nose that sometimes occurs with this condition.

Perspective and Prospects

Most acne vulgaris (about 60 percent) is treated at home. There has been significant improvement in the treatment of mild-to-moderate acne vulgaris, so for most of these patients, the condition can be limited to an annoyance or an inconvenience of the teen years. Only recalcitrant cases of acne vulgaris are seen by physicians. Of those cases treated by doctors, the majority are seen by family physicians, general practitioners, and other primary care workers. Severe acne is usually referred to the dermatologist, who is skilled in the use of the more serious medications and the more exacting techniques that are required in treatment.

For at least 85 percent of those experiencing puberty, acne vulgaris is a fact of life. It is a natural consequence of the hormonal changes that occur at this time. It is not likely that any drugs or techniques will be found to avoid acne in the teenage years, as this would involve tampering with a fundamental growth process. It can be expected, however, that in this condition, as in so many others, progress will continue to be made, and newer, more effective, and safer agents will be developed.

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