Pathophysiology of Acne Vulgaris Acne occurs through the interplay of 4 major factors: Excess sebum production Follicular plugging with sebum and keratinocytes Colonization of follicles by Cutibacterium acnes (formerly Propionibacterium acnes), a normal human anaerobe Release of multiple inflammatory mediators Acne can be classified as Noninflammatory: Characterized by comedones Inflammatory: Characterized by papules, pustules, nodules, and cysts Noninflammatory acne Comedones are sebaceous plugs impacted within follicles.