What designates a circumscribed collection of pus surrounded by a wall of inflammatory tissue?

A circumscribed collection of pus surrounded by a wall of inflammatory tissue is known as an abscess. This formation typically arises in response to an infection, where the body encapsulates the pus formed from dead cells, bacteria, and immune response elements in an effort to contain the infective process. The wall of inflammatory tissue surrounding the pus helps to isolate the infection from the surrounding healthy tissues, making it a significant feature of the abscess.

Ulcers refer to open sores that develop due to the loss of epithelial tissue, often as a result of conditions like prolonged pressure, inadequate blood supply, or infection, rather than a contained collection of pus. Fistulas, on the other hand, are abnormal connections or passages between two organs or vessels that normally do not connect, which is different from the localized nature of an abscess. Granulomas represent a specific type of chronic inflammation characterized by the formation of nodules, often associated with infectious or autoimmune conditions, and are not simply collections of pus.