What distinguishes a pustule from a papule?

The distinction between a pustule and a papule lies primarily in their content. A pustule is characterized as a small, raised, inflamed area of the skin that is filled with pus, which is a thick fluid composed of white blood cells, dead cells, and bacteria. This presence of pus defines a pustule and is typically associated with infections, such as acne.

In contrast, a papule is a small, solid, raised bump on the skin that does not contain pus. It may be red or pink, indicating inflammation, but it lacks the fluid-filled characteristics of a pustule. This clear difference in what fills these lesions—pus in pustules versus solid tissue in papules—highlights why the correct answer focuses on the presence of pus as the distinguishing factor. Understanding these definitions is important in the field of esthetics as it aids in accurate assessment and treatment of various skin conditions.