Four factors are involved in the pathogenesis of acne.
~ Increased production of sebum by sebaceous glands
~ Cornification of pilosebaceous ducts
~ An abnormality of microbial flora
~ Products of inflammation produced by Propionibacterium acnes such as lipase, protease, hyaluronidase and chemotactic factors. These products are comedogenic.
The factors that affect acne are genetic factor, androgens, extreme heat and humidity, stress, menstruation, sweating, dust, cosmetics, oil, sugary diet.
Acne lesions are polymorphic which comprises of comedones(black heads and white heads), papules, pustules, nodules,cysts and scars. The hallmark of acne is microcomedones. Acne lesions can be present on the chest and back.