[Cystic lesion with a displaced tooth in the maxillary sinus].

Ameloblastomas are epithelial odontogenic tumors in the mandibula or maxilla with potential local infiltrating growth; therefore, relapses can occur after incomplete resection. Among the different histological subtypes, the following are of clinical importance: The so-called unicystic ameloblastoma, radiologically presenting as a common dentigerous cyst, and the so-called extraosseous ameloblastoma. This case report describes the rare combination of a unicystic ameloblastoma with extraosseous localization in the maxillary sinus and association with a displaced tooth. This unusual constellation can cause major diagnostic problems.