Comedogenesis

Comedogenesis is the process by which comedones, commonly known as blackheads and whiteheads, are formed. This process is a key factor in the development of acne. It begins with the overproduction of sebum, an oily substance produced by the sebaceous glands in the skin. Simultaneously, there is an abnormal shedding of keratinocytes, the cells that make up the outer layer of the skin. These excess cells and sebum can then accumulate within the pilosebaceous unit, which consists of a hair follicle and its associated sebaceous gland.

The mixture of sebum and dead skin cells creates a blockage within the hair follicle. If this blockage is open to the surface of the skin, the trapped sebum and cells oxidize upon exposure to air, resulting in a blackhead. If the blockage is closed off from the air, the trapped material remains white or flesh-colored, forming a whitehead. This stagnant environment within the blocked follicle can also become a breeding ground for Cutibacterium acnes, a bacterium naturally present on the skin. The presence of this bacterium and the resulting inflammation contribute to the development of more severe acne lesions, such as papules, pustules, nodules, and cysts. Factors such as hormones, genetics, and certain medications can influence the rate and severity of comedogenesis.