A chalazion is a mass or cyst found in the upper or lower eyelid. It is benign, which means that it is not cancer. Chalazions are often chronic and can recur frequently.
A chalazion starts with inflammation of the meibomian gland. This is an eye gland that makes a substance that keeps the eyelids separated. If the eyelids stick together, one of the tear ducts can become blocked. This causes the eyelid to become inflamed, and the chalazion develops. This condition may take a few days to a few weeks to develop.
Chalazions are usually caused by a buildup of secretions in the meibomian gland that form a cyst. Chalazions occur most often in adults. They may be linked with other skin conditions, such as seborrheic dermatitis, blepharitis, and rosacea.