下顎歯肉扁平上皮癌の顎骨浸潤に関する臨床的ならびに病理組織学的検討

抄録

A clinical and histopathological study was carried out on the bone invasion by squamous cell carcinoma of the lower gingiva of 40 patients who were treated at the Division of Dentistry and Oral Surgery, Kagoshima Municipal Hospital, from January 1979 through December 1994. The tumors were classified into five categories: (a) invasion confined to the alveolo-gingiva area, (b) invasion extended to buccal mucosa, (c) invasion into the floor of the mouth, (d) invasion to buccal mucosa and the floor of the mouth, and (e) invasion of retro-molars. Radiologically determined bone absorption of 25 patients (62.5%) corresponded to the histopathologically identified tumor tissues. Of those 25 eighteen showed invasive bone resorption and seven were of the pressure type. Local recurrence rate was 12.5%( 5 of 40 patients) and most of those cases had their buccal mucosa invaded at their first visit. Histologically determined cervical lymph node metastases were recognized in 10 cases (25.0%), and eight of those 10 had their primary lesions extended to the floor of the mouth. The 5-years cumulative survival rate was 60.1%. Different prognosis was found to correlate with the extent of primary tumor into the surrounding tissues and cervical lymph node metastases. The primary tumor was histopathologically examined in 26 of 40 patients. The invasion of the tumor tissue into the mandible developed either through resorption of the cortical bone or through Haversian canal. In some of the tumor tissues in the bone marrow of the invasive type reactive new bone formation was observed, but in the pressure type fibrous tissue was found between the tumor tissue and the normal bone tissue. No direct resorption by the tumor tissue was recognized in the latter type. A correlation was seen between the X-ray finding of the bone resorption and the histologic extension of the tumor. This suggests that the radiological finding provides useful information to decide on an appropriate operative procedure for mandibulectomy.