Definition
- Acne vulgaris is a chronic inflammatory dermatosis which is notable for open and/or closed comedones (blackheads and whiteheads) and inflammatory lesions including papules, pustules, or nodules
- As of 2010, acne affects 9.4% of the global population, representing the 8th most prevalent disease
- Affects approximately 85% of teenagers, though is not limited to these age groups
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Pathophysiology
- Involves follicular hyperkeratinization, microbial colonization with Cutibacterium acnes, sebum production, complex inflammatory mechanisms involving both innate and acquired immunity, neuroendocrine mechanisms, and genetic and non-genetic factors
- Risk factors for the development of acne include increasing age during adolescence, family history of acne and oily skin type
- Adolescent acne is due to the hormonal surges as a child transitions into adulthood while post-adolescent acne is due to many contributing factors
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Contributing Factors
- Medications
- Corticosteroids, anabolic steroids, Lithium, some oral contraceptives (OC), retinoids, etc
- Androgen excess
- Signs of androgen excess: Precocious puberty, hirsutism, irregular menstruation, androgenetic alopecia
- Causes of androgen excess: Polycystic ovary disease or adrenal, ovarian, or pituitary tumor
- Pathogenesis: Androgen excess causes abnormal epithelial desquamation and obstruction of follicles, the latter secondary to sebum production forming open and closed comedones. Cutibacterium acnes (previously known as Propionibacterium acnes) proliferates due to sebum and causes inflammation around pilosebaceous unit manifested as papules, pustules, nodules, and cysts
- Mechanical
- Physical occlusion: Eg cosmetics (comedogenic), hats, head bands, mask-related acne (maskne), etc
- Other factors
- Resistant Cutibacterium sp and dysbiosis within the microbiome of the pilosebaceous follicle
- Innate and cellular immune responses, genetic predisposition, endocrine disorders (eg Cushing syndrome, androgen-secreting tumors, obesity)
- Consumption of westernized diet, intake of skim milk, chocolate, stress, smoking, poor quality of sleep, air pollution