title: Massive odontoameloblastoma arising in the maxilla: a case report.
abstract: BACKGROUND
  Odontoameloblastoma is an extremely rare mixed odontogenic tumor with both epithelial and mesenchymal components. The term odontoameloblastoma first appeared in the 1971 World Health Organization classification (Pindborg JJ., et al.) and is defined as "a neoplasm that includes odontogenic ectomesenchyme in addition to odontogenic epithelium that resembles an ameloblastoma in both structures and behavior." Because of the aggressive nature and risk of recurrence of the tumor, complete resection is essential. In this report, we describe an extremely rare case of a patient with massive odontoameloblastoma arising in the maxilla and occupying maxillary sinus.
  
  
  METHODS
  In 2013, an 11-year-old Japanese boy was referred to our department for a painless and large mass of the right maxillary region. A panoramic X-ray showed a unilocular cystic lesion in the right maxilla containing a calcified mass in the lesion associated with an impacted tooth. Computed tomography showed a cystic lesion that included calcified structures and measured 3.6×3.1×2.7 cm. In 2013, the patient underwent tumor extirpation combined with impacted tooth extraction. The histopathological diagnosis was an odontoameloblastoma. No recurrence was noted 27 months after the operation.
  
  
  CONCLUSIONS
  The patient has undergone postoperative occlusal guidance and functional orthodontic treatment, and his postoperative condition is excellent. However, postoperative recurrence or malignant transformation can occur in cases of odontoameloblastoma, and close long-term follow-up will be continued for our patient.
authors.affiliation: Division of Oral and Maxillofacial Surgery, Ebina General Hospital, 1320, Kawaraguchi, Ebina, Kanagawa, 243-0433, Japan. kumasa77@yahoo.co.jp.|Oral and Maxillofacial Surgery, Department of Oral Restitution, Division of Oral Health Sciences, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan. kumasa77@yahoo.co.jp.
authors.forename: Masanori
authors.initials: M
authors.lastname: Kudoh
authors.affiliation: Oral and Maxillofacial Surgery, Department of Oral Restitution, Division of Oral Health Sciences, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan. hiro-harada.osur@tmd.ac.jp.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Harada
authors.affiliation: Division of Oral and Maxillofacial Surgery, Ebina General Hospital, 1320, Kawaraguchi, Ebina, Kanagawa, 243-0433, Japan. sato.y.osur@tmd.ac.jp.|Oral and Maxillofacial Surgery, Department of Oral Restitution, Division of Oral Health Sciences, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan. sato.y.osur@tmd.ac.jp.
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Sato
authors.affiliation: Division of Oral and Maxillofacial Surgery, Ebina General Hospital, 1320, Kawaraguchi, Ebina, Kanagawa, 243-0433, Japan. omura.osur@tmd.ac.jp.|Oral and Maxillofacial Surgery, Department of Oral Restitution, Division of Oral Health Sciences, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan. omura.osur@tmd.ac.jp.|Division of Oral and Maxillofacial Surgery, General Tokyo Hospital, 3-15-2 Ekota, Nakano-ku, Tokyo, 165-0022, Japan. omura.osur@tmd.ac.jp.
authors.forename: Ken
authors.initials: K
authors.lastname: Omura
authors.affiliation: Division of Oral and Maxillofacial Surgery, Ebina General Hospital, 1320, Kawaraguchi, Ebina, Kanagawa, 243-0433, Japan. y_ishii@jin-ai.or.jp.|Oral and Maxillofacial Surgery, Department of Oral Restitution, Division of Oral Health Sciences, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan. y_ishii@jin-ai.or.jp.
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Ishii
mesh_terms: D000564:Ameloblastoma / Q000175:diagnosis* / Q000601:surgery; D002648:Child; D006801:Humans; D008297:Male; D008441:Maxillary Neoplasms / Q000175:diagnosis* / Q000601:surgery; D008443:Maxillary Sinus / Q000473:pathology*; D009808:Odontogenic Tumors / Q000175:diagnosis* / Q000601:surgery; D011862:Radiography, Panoramic; D014057:Tomography, X-Ray Computed; D014095:Tooth, Impacted