What should I know about Acne?
Acne vulgaris is the most common skin disease, affecting 80% of the population between the ages of 12 and 25.(1) It usually has a limited life span of its own; however, some cases may persist for years and the more severe cases may potentially lead to scarring and disfigurement. The lesions of acne are generally classified as inflammatory or noninflammatory, and occur most frequently on the face, neck, chest, and back.
The causes of acne are very complex and involve many different systems and chemicals within the body. Hormones, enzymes, and the immune system all interact together resulting in different reactions in each individual. Understanding this complex system has kept dermatologists busy for decades.
One of the factors responsible in the development of acne is called sebum, which is produced by the sebaceous glands. Sebaceous glands are located throughout the body except for the palms of the hands, soles of the feet, and the lower lip. Each person has approximately 5,000 sebaceous follicles. These glands are the largest and most numerous on the face, back, chest, and upper outer arms. Sebaceous glands are large at birth, and then reduce in size until adolescence. They once again enlarge during pre-puberty with changes in hormone levels influencing sebaceous gland secretion. This increase in production of sebum is the reason that acne is so prevalent in adolescents and teenagers.
When there is excess sebum, bumps called comedones, appear because there is a blockage of follicles by this excess sebum. Inside these comedomes, there are bacteria and yeast that work on the sebum causing it to release free fatty acids. When this happens, there is inflammation and sometimes a rupture of the bump or comedome. Sebum levels are increased when testosterone is converted into dihydrotestosterone in the skin. When this happens the dihydrotestosterone acts directly on the sebaceous gland to increase its size and metabolic rate. Estrogens, on the other hand, work differently and actually decrease sebaceous gland secretion. Early acne lesions result from blockage of the follicle canals. These canals become blocked when sebum mixes with keratin, which is also affected by hormonal changes. This new mixture increases the number of cornified cells that stick to the walls of the canal and a plug is formed just above the opening of the sebaceous gland duct. All of this change that occurs within the follicle is important, but not fully understood. It is not known whether this activity is a cause of or a result of irritation and other factors.(2)
The earliest lesions that are most often seen in adolescence are mildly inflamed or non-inflamed comedones on the forehead. Comedones may be open (blackhead), or closed (whitehead). The contents of closed comedones are usually not easily expressed, and are often the first sign of the inflammatory lesions of acne vulgaris. It is unsure where open comedones get their black color. It is not from accumulation of dirt, and may not even be the accumulation of melanin, which was the source most recently thought to be the cause. Open comedones generally do not result in inflammatory acne lesions, are easily expressible, and contain oxidized, darkened, oily debris.
The severest forms of acne are most frequently seen in males, but acne is generally more persistent in females. Also, females tend to have flare-ups prior to menstrual periods. This may continue until menopause. Low grade, persistent acne is often found in professional women. One author thinks that chronic stress leads to enhanced secretion of adrenal androgens, resulting in the production of comedones.(3)
Acne is considered an inherited disease, although it is impossible to know which members of a family may suffer from the disease, and which members will not. Acne is not caused by greasy foods, and is not caused by dirt. Avoiding all greasy foods may help curb obesity, but will likely not affect acne. While keeping the skin clean is always recommended, excessive washing of the skin to remove dirt may actually interfere with some treatment programs. For this reason, when visiting a healthcare professional regarding acne, it is important to request information on how to care for the skin at home.
Sometimes acne is caused by elements that are not internal. One such type of acne is termed occupational acne, and involves exposure to certain industrial solvents or other chemicals. Another type of acne is called acne mechanica and is caused by irritation of the skin by the use of chin-straps or forehead guards often found inside of sports helmets.
Acne may sometimes become very severe. This category of acne, known as nodulocystic acne, includes localized cystic acne, in which a few cysts appear on the face, chest, or back, and diffuse cystic acne, which involves a wider area of cystic lesions. Pyoderma faciale is the term that is used for inflamed cysts that appear on the face in females. Acne conglobata describes a highly inflammatory form of nodulocystic acne. Acne fulminans is a rare ulcerative form of acne with an unknown cause. 40% of patients with acne fulminans experience painful bone lesions, muscle pain, and sometimes weight loss.