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.
The microcomedo may enlarge to form an open comedo (blackhead) or closed comedo (whitehead). Whiteheads are the direct result of skin pores becoming clogged with sebum, a naturally occurring oil, and dead skin cells.