COMEDO

A comedo is a hair follicle infundibulum that is dilated and plugged by keratin and lipids. When the pilosebaceous unit is open to the surface of the skin with a visible keratinaceous plug, the lesion is referred to as an open comedo. The black color of the comedo is due to the oxidized sebaceous content of the infundibulum (“blackhead”). A closed infundibulum in which the follicular opening is unapparent accumulates whitish keratin and is called a closed comedo. These lesions are common on the face and trunk. A clinical example is comedonal acne