What type of lesion is characterized by an inflamed area typically filled with pus?

A lesion that is characterized by an inflamed area filled with pus is known as a pustule. Pustules are small, elevated lesions that occur when the skin's immune response to infection, inflammation, or irritation results in the accumulation of pus. This pus is a thick fluid composed of dead white blood cells, bacteria, and tissue debris, typically indicating an infection or inflammation.

In contrast, a vesicle is a small blister containing clear fluid, an ulcer is an open sore that results from the loss of the skin's surface, and a nodule is a solid, raised lesion that is generally deeper in the skin and may or may not contain fluid. These characteristics clearly distinguish a pustule from the other types of lesions, emphasizing its specific role in the body's response to infection.