Unusual cyst of the zygoma.

An unusual cyst of the zygoma is described. Three patterns of development of the cyst are suggested, namely: 1. Residual cyst of retained deciduous roots with metaplasia of the odontogenic epithelium into respiratory epithelium. 2. Fissural cyst of the zygomatico-maxillary suture. 3. Connection to the maxillary sinus, by a developmental exvagination or trauma to the sinus that caused entrapment of epithelium at the fracture line, with subsequent proliferation.