The pathophysiology of acne.

Acne is a multifactorial inflammatory disease affecting pilosebaceous follicles. The initial event in the development of an acne lesion is abnormal desquamation of the keratinocytes that line the sebaceous follicle, which creates a microplug or microcomedo. An increase in circulating androgens at the onset of puberty stimulates the production of sebum into the pilosebaceous unit. These events combine to create an environment within the pilosebaceous unit that is favorable for the colonization of the commensal bacteria, Propionibacterium acnes. With proliferation, P acnes secretes various inflammatory molecules and chemotactic factors that initiate and perpetuate the local inflammatory response and possibly induce keratinocyte hyperproliferation as well.