Chalazion or meibomian cyst (lump in eyelid) Chalazion overview A chalazion, also known as a meibomian cyst, is a lump in the eyelid that is caused by inflammation of a gland within the skin. Typically, this lump grows over days and weeks and is occasionally red, warm or painful. The gland involved in the formation of a chalazion is a modified sweat gland that lies within the eyelid and opens onto the inside of the eyelid. This gland produces oil. When this gland becomes blocked, it can rupture and the inflammation process begins.