上顎に生じた歯原性粘液線維腫の1例

抄録

Although odontogenic myxofibroma is generally taken as a benign, slow-glowing and nonmetastasizing mesenchymal tumor, the tumor etiology is still unknown and special attention should be paid in the treatment of this tumor because of its insidious clinical characteristics, i. e. high rate of local recurrence.
A case of maxillary odontogenic myxofibroma that appeared in a 40-year-old female is described and the histogenesis as well as pathogeny of the lesion is discussed.
The patient's chief complaint was a painless, slightly hard and expansive swelling of the gingiva in the left canine region of the maxilla.Radiographic examination disclosed an unilocular, well circumscribed radiolucent lesion of the maxilla and nonerupted canine. CT scanning showed a tumorous change and incisional biopsy revealed the lesion to be a myxomatous disease.
With the patient under general anesthesia, extirpation of the tumor together with the impacted canine as well as extraction of both the central incisor and premolar on the left side of the maxilla were performed.At about 4 years postoperatively, no evidence of recurrence has appeared.
Histopathological investigation of the tumor under light microscope revealed spindle, stellate-shaped and polyhedral cells in a fibromyxoid stroma with an occasional odontogenic epithelial island resembling an ameloblastic epithelium. No abnormal mitoses of the tumor cells were seen.
Ultrastructurally, poorly differentiated fibroblast-like cells were noted. It is suggested that the tumor cells were derived from undifferentiated mesenchymal cells in the periodontal membrane of the impacted canine. However, it might also be possible, on the other hand, that a transformation of the fibroblast in the periodontal membrane of the impacted canine into a poorly differentiated fibroblast-like cell occurred and the transformed cell subsequently developed the odontogenic myxofibroma.