What constitutes a pustule in terms of cellular composition?

A pustule is defined as a small inflamed elevation of the skin that is filled with purulent (pus-filled) material. The cellular composition of a pustule is primarily composed of a clump of white blood cells, which are part of the body’s immune response to infection or irritation. When the skin is affected by an infection, such as acne, white blood cells migrate to the site to combat the pathogens, leading to the accumulation of pus.

This pus, which is often a creamy yellow or white substance, is a mixture of dead white blood cells, bacteria, and tissue debris. The presence of these white blood cells is what characterizes the condition as a pustule, as they signify that the body is actively fighting an infection or responding to inflammation.

In contrast, other options may refer to conditions that do not accurately depict a pustule. For instance, a buildup of sebum relates to acne but does not provide the inflammatory response evident in a pustule. Similarly, dead skin and bacteria would not necessarily lead to the formation of a pustule without the accompanying white blood cells. A raised bump filled with fluid can describe a blister, which has a different underlying composition and causes. Thus, the identification of a pustule as a cl