What defines a cyst?

A cyst is defined as a closed sac or pouch that can form within the skin or other tissues, filled with fluid, semi-solid material, or even air. This definition is key because it reflects the structural characteristic of a cyst being encapsulated, as opposed to other skin lesions that may not have this distinct boundary.

Cysts can vary in size and can occur in various locations on the body. Their formation can be a result of infection, clogging of sebaceous glands, or other factors, but the defining feature remains the closed nature of the sac, which is essential for distinguishing cysts from lacerations, types of acne lesions, or other forms of lesions that may not have such encapsulated structures.