what is the medical term used for \" a dilated hair follicle filled with bacteria and sebum\"? Solution A dilated hair follicle filled with bacteria and sebum is medically called Comedo. Commonly it is said blackhead or whitehead. It is a clogged hair follicle in the skin. It comes from the latin word \"comedere\" meaning to eat up which was used to describe parasitic worms. In modern medical terminology it describes the worm like appearance of the expressed material..