Acne develops as a result of blockages in follicles Hyperkeratinization and formation of a plug of keratin and sebum (a microcomedo) is the earliest change. Enlargement of sebaceous glands and an increase in sebum production occur with increased androgen (DHEA-S) production at adrenarche. The microcomedo may enlarge to form an open comedo (blackhead) or closed comedo (whitehead). Increased sebum production provides an environment for the overgrowth of Propionibacterium acnes. Bacterial overgrowth of Propionibacterium acnes can cause inflammation, leading to inflammatory lesions (papules, pustules, or nodules) in the dermis around the microcomedo or comedo, which may result in scarring.