抄録
Detailed microscopic examination on a total of 31 cases of ameloblastoma was conducted using, as a preliminary step, a number of large-sized tissue sections covering whole body of the tumor, and the possible structural difference due to their localities of origin was carefully investigated between individual tumors occurring respectively in molar teeth and frontal teeth regions of lower jaw and those occurring in upper jaw. Particularly, with tumors occurring in the lower molar region, effort was centered to elucidate possible histological difference existing between segments of individual tumor body constituting its buccal, lingual, mesial, distal, alveolar, and lower marginal sides. Careful study was further extended to the relationship between the tumor and the surrounding tissues, and the findings were comparatively studied with reference to the clinical symptomes. Conclusions obtained are as follows. 1) Difference in the radiologic and patho-histologic findings was found to exist between group of 24 ameloblastomas occurring in lower molar region and group of 7 ameloblastomas occurring in lower frontal teeth region and in upper jaw. 2) Of 24 ameloblastoma occurring in lower molar region relatively large number (15 cases) showed the radiologic picture typical of the tumor, and in about equal number of the tumor segmental difference was detected from patho-histological viewpoint (17 cases). However, in every cases of these tumors, parenchymatous networks had close resemblance to the structure of enamel organ. 3) With all the cases of ameloblastoma occurring in upper jaw and lower frontal teeth region, atypical radiologic picture was observed, and segmental patho-histologic difference was poorly observed. In most of the cases (6 out of 7) the parenchymatous networks showed poor resemblance to the structure of enamel organ. 4) Of those tumors occurring in lower molar region, there was found parallelism of histological findings between the alveolar and lower marginal sides, and between the buccal and lingual sides of a single tumor, and, this permitted clearer presentation of the tumor structure by comparing above two sets of findings. Thus, histologic difference was found to be existing between the two sets of findings in eleven out of 24 cases. Comparison between the mesial and distal sides segments of the tumors revealed difference existing in 10 cases out of the total tumors. It was further noted of the histological difference that tendency to cyst formation was most conspicuous in the distal than in the bucco-lingual segments and least conspicuous in the alveolar and lower marginal segments through the tumors. This difference was also observed in the growth pattern of the tumors, alveolar and lower marginal segments being most infiltrative, the bucco-lingual less infiltrative and the distal segments expansive with well-defined boundary to the surrounding tissues.
