What does a pustule contain?

A pustule specifically contains pus, which is a thick fluid composed of dead white blood cells, bacteria, and tissue debris that accumulates during inflammation or infection. This fluid is typically the result of the body's immune response to an irritant or pathogen, indicating that the body is fighting off infection. Unlike other options, a pustule is not filled with blood, clear fluid, or dead skin cells; instead, it is characterized by its cloudy or yellowish appearance due to the presence of pus. Understanding the composition of a pustule is essential for nail technicians, as it helps them differentiate between various skin conditions and determine appropriate treatment or referral to a healthcare professional.