An eruption cyst, or eruption hematoma, is a bluish swelling that occurs on the soft tissue over an erupting tooth. It is usually found in children. The fluid in the cyst is sometimes clear creating a pale-coloured cyst although often they are blue. An eruption cyst (eruption hematoma) is a developmental soft-tissue cyst of odontogenic origin that forms over an erupting tooth. most commonly seen anterior to first molar