Acne is a disease of pilosebaceous units in the skin. It is thought to be caused by the interplay of four factors. Excessive sebum production secondary to sebaceous gland hyperplasia is the first abnormality to occur.1 Subsequent hyperkeratinization of the hair follicle prevents normal shedding of the follicular keratinocytes, which then obstruct the follicle and form an inapparent microcomedo. Lipids and cellular debris soon accumulate within the blocked follicle. This microenvironment encourages colonization of Propionibacterium acnes, which provokes an immune response through the production of numerous inflammatory mediators. Inflammation is further enhanced by follicular rupture and subsequent leakage of lipids, bacteria, and fatty acids into the dermis. The diagnosis of acne is based on the history and physical examination. Lesions most commonly develop in areas with the greatest concentration of sebaceous glands, which include the face, neck, chest, upper arms, and back. Acne vulgaris may be defined as any disorder of the skin whose initial pathology is the microscopic microcomedo. The microcomedo may evolve into visible open comedones (“blackheads”) or closed comedones (“whiteheads”). Subsequently, inflammatory papules, pustules, and nodules may develop. Nodulocystic acne consists of pustular lesions larger than 0.5 cm. The presence of excoriations, postinflammatory hyperpigmentation,
and scars should be noted. Acne may be triggered or worsened by external factors such as mechanical obstruction (i.e., helmets, shirt collars), occupational exposures, or medications. Common medications that may cause or affect acne are
Cosmetics and emollients may occlude follicles and cause an acneiform eruption. Topical corticosteroids may produce
perioral dermatitis, a localized erythematous papular or pustular eruption. Endocrine causes of acne include Cushing’s disease or syndrome, polycystic ovary syndrome, and congenital adrenal hyperplasia. Clinical clues to possible hyperandrogenism in women include dysmenorrhea, virilization (i.e., hirsutism, clitoromegaly, temporal balding), and severe acne.
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