Risk factors for the development of acne, other than genetics, have not been conclusively identified. Possible secondary contributors include hormones, infections, diet and stress. Studies investigating the impact of smoking on the incidence and severity of acne have been inconclusive. Sunlight and cleanliness are not associated with acne.
Whereas acne vulgaris clogs pores from the bottom up, acne inversa (or hidradenitis suppurativa) is a form of acne that clogs pores from the top down. It’s caused by excessively rapid skin growth, occluding the mouth of pores with shed skin cells. When the pores are blocked and clogged, they become inflamed and can create pimples and acne lesions. This form of acne is usually observed in intertriginous skin, where two skin areas may touch or rub together. Induced or aggravated by heat, moisture, maceration, friction and lack of air circulation. Examples of these areas include underarms, folds of the breasts, and between buttocks cheeks.
Acne appears when a pore in our skin clogs. This clog begins with dead skin cells. Normally, dead skin cells rise to surface of the pore, and the body sheds the cells. When the body starts to make lots of sebum (see-bum), oil that keeps our skin from drying out, the dead skin cells can stick together inside the pore. Instead of rising to the surface, the cells become trapped inside the pore.