Keratocystic odontogenic tumor (KCOT) is a benign odontogenic tumor with a potentially aggressive and infiltrative behavior. KCOT is most commonly occurred in mandible and demonstrate a unilocular, round, oval, scalloped radiolucent area, while large lesions may appear multilocular. An important characteristic of KCOT is its propensity to grow in an antero-posterior direction within medullary cavity of bone causing minimal expansion. Definitive diagnosis relies on histological examination. In this report, a KCOT that had an expansion both buccal and lingual ortical bone is described including its features in computed tomography and ultrasonographic exams. The lesion was removed surgically via an intraoral approach under local anesthesia and histologically reported as a KCOT. © 2012 by Korean Academy of Oral and Maxillofacial Radiology.