What characterizes a pustule?

A pustule is specifically characterized as a papule that contains pus. This distinction is important because it indicates not only the elevation of the skin but also the presence of purulent fluid, which is often a sign of inflammation or an infection. Pustules are typically associated with conditions like acne, where clogged pores can lead to bacterial growth and subsequent pus formation. Recognizing a pustule involves noting its raised appearance typically accompanied by redness, and its contents, which are often cloudy or yellowish due to the pus. Understanding this characteristic helps in the assessment and treatment of various skin conditions, as pustules can indicate a different condition than other types of lesions, such as flat marks or solid lesions.