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Acne Vulgaris Pathophysiology
Aka: Acne Vulgaris Pathophysiology
- See Also
- Acne Vulgaris
- Acne Vulgaris Management
- Adjunctive Acne Vulgaris Management
- Moderate Acne Vulgaris Management
- Severe Acne Vulgaris Management (includes Cystic Acne)
- Pathophysiology: Overview
- Acne Progression (4 step process)
- Androgen Mediated Sebum Production
- Keratinous Obstruction of sebaceous follicle outlet (Results in formation of comedones)
- Bacterial Colonization of trapped sebum (with Cutebacterium acnes, previously Propionibacterium acnes)
- Inflammatory reaction (Papules, Nodules and cysts)
- Images
Lewis (1918) Gray's Anatomy 20th ed (in public domain at Yahoo or BartleBy)
- Pathophysiology: Androgen Mediated Sebum Production
- Causes
- Adrogen-mediated sebum over-production
- Increased Sebaceous Gland sensitivity to normal androgen levels
- Sebum composition
- Triglycerides
- Cholesterol esters
- Waxes
- Fatty Acids
- Sebum Effects
- Drains to skin surface via pilosebaceous canal
- Excellent growth medium for Cutebacterium acnes (previously Propionibacterium acnes)
- Pathophysiology: Keratinous Obstruction of sebaceous follicle outlet
- Abnormal follicular epithelium shedding
- Pre-Puberty Sebaceous follicles
- Lobulated glands empty into pilosebaceous canal
- Follicles most dense on face, back and chest
- Inactive until Puberty
- Post-Puberty Sebaceous follicles
- Androgen production increases
- Stimulates sebaceous follicles to secrete sebum
- Pathophysiology: Comedones form from keratin and sebum collection
- Open Comedones (Black heads)
- Combination of sebum and keratin
- Melanin gives them the black color
- Seldom become inflamed
- Closed Comedones (White heads)
- Do not communicate with the skin surface
- Block pilosebaceous canal
- Encourage Anaerobic Bacteria to grow
- Propionibacterium acnes fuels inflammatory process
- Lipase secretion lyses Triglycerides
- Free Fatty Acids fuel local irritation
- Closed comedones progress to inflammatory lesions
- Pathophysiology: Bacterial Colonization of trapped sebum
- Cutebacterium acnes (previously Propionibacterium acnes) Bacteria colonizes sebum
- P. acnes secretes a Lipase that hydrolyzes sebum
- Converts Triglycerides into free Fatty Acids
- Free Fatty Acids irritate local cells
- Pathophysiology: Inflammatory reaction (usually in closed comedones)
- Papules
- Pustules
- Nodules
- Cysts
- References
- James (2005) N Engl J Med 352(14):1463-72 [PubMed]
- Oge (2019) Am Fam Physician 100(8): 475-84 [PubMed]
- Strauss (2007) J Am Acad Dermatol 56(4): 651-63 [PubMed]
- Titus (2012) Am Fam Physician 86(8): 734-40 [PubMed]