What is the term for a mass of sebum, keratin, and debris blocking the opening of a hair follicle?

The term for a mass of sebum, keratin, and debris that blocks the opening of a hair follicle is known as a comedo. Comedones are commonly classified into two types: open comedones, which are also referred to as blackheads, and closed comedones, known as whiteheads. The blockage results from the accumulation of the sebaceous material, which can lead to the development of acne if inflammation or infection occurs.

Understanding the characteristics of comedones helps clarify their role in skin conditions such as acne vulgaris, where multiple comedones may contribute to the formation of pimples and cystic lesions. The differentiation between open and closed comedones is important in dermatology for treatment approaches, as open comedones are more susceptible to oxidation, causing their characteristic dark appearance.

The other terms listed refer to different conditions: a cyst typically describes a fluid-filled or semi-solid cavity within tissue, a furuncle is an abscess within a hair follicle, and a carbuncle is a larger, more severe form of a furuncle that consists of interconnected furuncles. Each of these has distinct pathophysiological features and implications in skin health.