The mother brings her 2 year old child to OPD with gum swelling on lower back tooth region. On intraoral examination, smooth - surfaced bluish lesion associated with erupting 75. Radiographic examination reveals a soft tissue shadow and there is no bone involvement. What is the most probable diagnosis?

Eruption cyst is defined as an odontogenic cyst with the histologic features of a dentigerous cyst that surrounds a tooth crown that has erupted through bone, but not soft tissue and is clinically visible as a soft fluctuant mass on the alveolar ridges. An eruption cyst or ‘eruption hematoma’ is in fact a dentigerous cyst occurring in the soft tissues (Shear, 1992). Whereas, the  dentigerous cyst develops around the crown of an unerupted tooth lying in the bone, the eruption cyst occurs when a tooth is impeded in its eruption within the soft tissue overlying the bone. Shafer's Oral pathology Pg- 263, 264