What is the definition of a comedone?

A comedone is defined as a mass of hardened sebum and dead skin cells that clogs hair follicles. This obstruction can occur when excess oil (sebum) produced by sebaceous glands mixes with dead skin cells and becomes trapped within the pore, leading to the formation of either open or closed comedones. Open comedones, commonly referred to as blackheads, are characterized by their dark appearance due to oxidation of the trapped material at the skin's surface, while closed comedones, known as whiteheads, remain beneath the skin and can appear as small, flesh-colored bumps. Understanding the proper definition helps highlight the role of comedones in skin conditions, particularly in acne, as they are a precursor to more severe forms of the condition.