CASE REPORT Odontogenic keratocyst in maxillary sinus with invasive behaviour Eneida Franco Vencio, Alessandra Mota, Carolina de Melo Pinho, Aylton Alves Dias Filho Department of Oral Pathology, School of Dentistry, Federal University of Goias, Goiania, Brazil Odontogenic keratocyst is a cystic lesion characterized by a high rate of recurrence. This report describes a rare case of ciliated epithelium-lined odontogenic keratocyst in the maxilla of a 27-year-old female. Panoramic radio- graphy showed a lytic lesion on the right maxilla asso- ciated with an impacted molar tooth. Computerized tomography image revealed the involvement of the le- sion with the right maxillary sinus, destroying the sinus floor. Histopathologically, the typical keratinized epithe- lial-lined cyst of odontogenic keratocyst abruptly changed into a ciliated epithelium, suggesting the fusion of both these epithelia rather a metaplastic transformation. The biological behaviour of odontogenic keratocysts is dis- cussed. J Oral Pathol Med (2006) 35: 249–51 Keywords: invasion; maxillary sinus; odontogenic keratocyst; respiratory epithelium Case description A 27-year-old woman complained of tooth pain in the right first maxillary molar. Intra-orally the right maxillary second molar was absent. Computerized tomography (CT) scans showed a lesion in the right maxilla extending to the maxillary sinus floor. An impacted right second maxillary molar was involved in the lesion (Fig. 1). A CT axial view disclosed an opaque lesion in the right maxillary sinus, partially filling the right maxillary sinus and destroying the right sinus floor (Fig. 2). The patient underwent a resection by curettage and no evidence of recurrence was registered 5 years later. Microscopically, the cyst was covered with a stratified squamous epithelium with few layers, a parakeratinized, corrugated surface, and a palisading pattern of basal cells with polarized and hyperchromatic nuclei. The cystic lining lost its stratified aspect and abruptly became columnar and ciliated (Fig. 3). Two connection points between the Figure 2 Computerized tomographic axial view showing a lesion involving the right maxillary sinus with cloudy appearance and destroying the lateral wall of the maxillary sinus. Correspondence: Eneida F. Vencio, Universidade Federal de Goias, Faculdade de Odontologia, Disciplina de Patologia Bucal, Prac¸a Universita´ ria, SN, 74605-220, Goiania-GO, Brazil. Tel: +55(0)62 3209 6058. Fax: +55(0)62 3521 1886. E-mail: vencio@odonto.ufg.br Accepted for publication November 23, 2005 Figure 1 A computerized tomography scan showing a lesion in the right maxilla extending to the maxillary sinus floor. Note the involvement of the right maxillary second molar impacted tooth. J Oral Pathol Med (2006) 35: 249–51 ª 2006 The Authors. Journal compilation ª 2006 Blackwell Munksgaard All rights reserved www.blackwellmunksgaard.com/jopm