Glands in the skin—called sebaceous glands—secrete sebum, which lubricates the skin. Just as using anabolic steroids leads to muscular hypertrophy, or size increases, it also leads to growth of the sebaceous glands, which then produce more sebum. That combines with abnormal production of keratin in the skin to cause the formation of comedos, which have nothing to do with comedy and aren’t the least bit funny. They are, in fact, preacne lesions that contain larger amounts of skin lipids, including cholesterol and free fatty acids. Those fats are like a buffet for bacteria that is normally latent in the skin, and the bacteria thrive. Their banquet produces extremely inflammatory end products in the skin follicles, resulting in the inflammation characteristic of acne.
you get the just of it.