Final answer:
Pustules are the primary lesions that are small elevations of skin similar in size and shape to vesicles but contain pus. They are indicative of a suppurative infection and commonly associated with conditions like impetigo and acne.
Step-by-step explanation:
The primary lesions that are small elevations of skin similar to vesicles in size and shape but contain pus are called pustules. Pustules are a type of suppurative (pus-producing) infection of the skin. They may appear as small raised bumps on the skin and can result from various skin conditions, like impetigo, which is characterized by the formation of vesicles, pustules, and possibly bullae, particularly around the nose and mouth. In impetigo, the pustules rupture and often become encrusted sores, typically with a distinctive yellowish crust.
An example of such a skin lesion is acne, where an inflammation of hair follicles can lead to the formation of pustules. Pustules can also result from more serious infections like furuncles and carbuncles, which are generally associated with Staphylococcus bacteria.