Simultaneous occurrence of keratocystic odontogenic tumor and ameloblastoma in the mandible: A case report

Abstract

Keratocystic odontogenic tumors (KCOTs) and ameloblastomas are benign odontogenic tumors that primarily occur in the molar region of the mandible. However, it is uncommon for these tumors to arise simultaneously in a patient's jaw. The present study reported the diagnostic process and features of a rare case of the simultaneous occurrence of KCOT and ameloblastoma in the mandible of a 45-year-old male. Image-based diagnosis was challenging due to several conditions, including the intactness of the teeth and bone cortex as well as the sizes and locations of the lesions. Based on radiographic evidence, the patient was initially misdiagnosed and underwent a biopsy for a radicular cyst and a simple bone cyst prior to the correct diagnoses of KCOT and ameloblastoma, respectively. In addition, the present study discussed the diagnostic process of the present case and reviewed previous literature regarding the simultaneous occurrence of benign tumors of the jaw.

Keywords: ameloblastoma; computed tomography image; keratocystic odontogenic tumor; panoramic image; simultaneous occurrence of odontogenic tumors.

Figure 1.

Initial panoramic radiograph demonstrates the presence of two round-style radiolucent lesions. One lesion was identified around the root apex of the lower-right first molar (white arrows) and another lesion was observed in the inter-alveolar septum of the lower-right premolars (black arrowhead). The imaging diagnoses of the two lesions were a radicular cyst and a simple bone cyst, respectively.

Figure 2.

Computed tomography images of the patient's mandible. (A) An axial view showing the cross-section of the mandible from the patient's foot side. A 15-mm sized, round-style, well-defined cystic lesion was detected on the root apex of lower-right first molar (arrow); in addition, a 12-mm sized, radiolucent lesion was identified in the inter-alveolar septum of the lower-premolars (arrowhead). (B) An axial view demonstrated the root divergency of lower-right premolars (arrowhead). (C) A para-sagittal view revealed the septum inside the ameloblastoma as well as divergency of lower-right premolars. (D) Reference image of the orthogonal reconstruction. Numbers assigned are equivalent to the image number of each orthogonal view. (E) Orthogonal views depicting the keratocystic odontogenic tumor revealed the septum inside the KCOT (arrows). (F) Orthogonal views identifying the ameloblastoma.

Figure 3.

Histopathological analysis of the specimens obtained from the lesions following incisional biopsy. (A) Specimen from the root apex of the lower-right first molar revealed a thin layer of regularly parakeratinized stratified squamous epithelium and fibrous connective tissue. The histopathological diagnosis was of keratocystic odontogenic tumor. (B) Specimen from the inter-alveolar septum of the lower-right premolars revealed trabeculation of enamel organ-like tissue. Histopathological analysis indicated ameloblastoma. Specimens were stained with hematoxylin-eosin and images were captured at original magnification, x20).

Figure 4.

Soft X-ray images of the excised tumors. Images were captured of (A) the excised KCOT and (B) the ameloblastoma with adjacent teeth and alveolar bone. Soft X-ray images were then captured of (C) the KCOT specimen and (D) the ameloblastoma specimen, which demonstrated details of the internal structures of the lesions. KCOT, keratocystic odontogenic tumor.