Final answer:
Follicular casts often co-exist with inflammatory lesions such as papules. They result from infections typically caused by the bacterium Propionibacterium acnes, which damages hair follicles and produces various skin lesions.
Step-by-step explanation:
Follicular casts often co-exist with inflammatory lesions such as papules, pustules, nodules, or pseudocysts. These lesions are a result of an infection of hair follicles often caused by Propionibacterium acnes, which is involved in acne formation. The bacterium secretes enzymes that damage the hair follicle leading to these skin conditions. Specifically, follicular casts are associated with papules, dome-shaped lesions that can be red and inflamed.
When considering skin lesions, it is important to understand how bacteria like P. acnes lead to the development of various types of lesions. For example, the infection of a hair follicle can become purulent forming a furuncle, or it can lead to an abscess, a pus-filled lesion. It's the body’s response to the bacterial infection that leads to these distinct skin presentations.