Acne Vulgaris Definition
Acne vulgaris is a chronic inflammatory dermatosis of the pilosebaceous unit characterized by open or closed comedones (blackheads and whiteheads) and inflammatory lesions including papules, pustules, or nodules (also known as cysts), primarily affecting the face and trunk. 1
Clinical Presentation
The disease manifests through distinct lesion types that define its clinical appearance:
- Comedonal lesions: Open comedones (blackheads) and closed comedones (whiteheads) represent the non-inflammatory component 1
- Inflammatory lesions: Papules, pustules, and nodules (cysts) constitute the inflammatory manifestations 1
- Distribution: Lesions predominantly occur in sebaceous-rich areas of the face and trunk in a typically symmetrical pattern 2
- Sequelae: The condition may result in permanent scarring, post-inflammatory erythema, and hyperpigmentation 1, 3
Pathophysiology
Acne vulgaris results from multifactorial pathogenic mechanisms affecting the pilosebaceous follicle:
- Follicular hyperkeratinization: Abnormal keratinization of the follicular duct leads to comedone formation 1
- Sebum production: Androgen-induced sebaceous gland hyperplasia causes excessive sebum secretion 2
- Microbial colonization: Cutibacterium acnes (formerly Propionibacterium acnes), a Gram-positive anaerobic rod, plays a central role in disease pathogenesis 1
- Inflammatory mechanisms: Complex innate and acquired immune responses drive the inflammatory component 1
- Contributing factors: Neuroendocrine mechanisms, genetic predisposition, and environmental factors all contribute to disease development 1
Epidemiology and Disease Burden
The global impact of acne vulgaris is substantial:
- Prevalence: Affects 9.4% of the global population, representing the eighth most prevalent disease worldwide 1
- Age distribution: Approximately 85% of teenagers are affected, though the condition can occur across most age groups and persist into adulthood 1, 4
- Adult prevalence: About 12% of adult women experience acne 1
- Economic burden: In the US, over 5.1 million Americans sought medical treatment in 2013, resulting in $846 million in medical costs and $398 million in lost productivity 1
Psychosocial Impact
The quality of life impact of acne is comparable to chronic conditions such as asthma, psoriasis, and arthritis, with no mortality but significant physical and psychological morbidity. 1, 3
The disease affects multiple life domains:
- Psychological effects: Increased risks of depression, anxiety, poor self-esteem, and suicidal ideation 1, 3
- Social consequences: Stigmatization, bullying, and impaired social functioning 1, 3
- Functional impairment: Negative effects on emotional functioning, relationships, leisure activities, daily activities, sleep, school, and work performance 1, 3
- Physical sequelae: Permanent scarring and skin disfigurement contribute to ongoing psychological distress 1, 5
Risk Factors
Specific factors increase the likelihood of developing acne:
- Age: Increasing age during adolescence correlates with higher acne prevalence 1
- Family history: Genetic predisposition plays a significant role 1
- Skin type: Oily skin type increases risk 1
- Environmental factors: Sun exposure, skincare habits, diet, sleep patterns, and psychological stress can induce or exacerbate the condition 2