下顎小臼歯歯肉に生じた周辺性エナメル上皮腫の1例

抄録

Peripheral ameloblastoma(PA)is a rare extraosseous odontogenic tumor with histologic characteristics similar to those of commonly occurring intraosseous ameloblastoma. However, PA is rarely associated with invasive or aggressive intraosseous lesions. PA originates from one of two sources: extraosseous remnants of the dental lamina, or the basal cell layer of the oral epithelium. We describe a patient with a PA and report the results of immunohistochemical studies of Ki-67 antigen using MIB-1 antibody.
A 48-year-old man was referred to us because of a painless mass of 1 years' duration on the buccal gingival region of the lower left premolar. The mass, 1.0cm in diameter, was hemispherical, sessile, firm, and nontender. Radiographic examination showed no resorption of bone. The mass was clinically diagnosed to be an epulis and was excised under local anesthesia. The surface of the denuded bone was removed owing to the presence of a small depression with granulation tissue. Routine pathological examination demonstrated ameloblastoma of follicular type. Immunohistochemical examination showed that 21.5 % of the tumor cells were Ki-67 antigen positive. The results suggested that the tumor cells may have high growth potential. There has been no sign of recurrence for 2 years 6 months.