What type of acne lesion can appear as both purulent and non-purulent?

A papule is a type of acne lesion characterized by a small, raised bump on the skin that is solid and can range in color from red to brown. Papules can be both purulent and non-purulent depending on their stage of development and severity.

When a papule is still in the early stages and contains no pus, it is considered non-purulent. However, if the condition worsens and becomes infected, the center of the papule can fill with pus, transforming it into a purulent lesion. This ability to present in both states makes papules unique compared to other types of acne lesions, which typically have a more distinct classification based on whether they are purulent or non-purulent.

Open and closed comedones, on the other hand, are primarily non-inflammatory lesions. Open comedones (blackheads) remain blocked at the surface, while closed comedones (whiteheads) are formed deeper within the follicle, which also does not exhibit purulent characteristics unless they evolve into inflammatory lesions. Pustules are filled with pus and are specifically recognized as purulent lesions, lacking the capability to be non-purulent.