What type of cysts are known as milia?

Milia are small, white, keratin-filled cysts that commonly appear on the skin, particularly on the face, around the eyes, and on the cheeks. They typically do not have a visible opening on the skin's surface, which distinguishes them from other types of cysts. These cysts are formed when keratin—a protein found in the skin—becomes trapped beneath the surface. Unlike fluid-filled cysts or those filled with pus, milia contain a solid component, making the correct characterization as keratin-filled. Their small size and the absence of an opening often lead to their misinterpretation as whiteheads, but they are a distinct type of cyst. Understanding this helps clarify their unique formation and characteristics compared to other types of cysts mentioned in the options.