Verrucous carcinima can be defined in clinical, morphologic, and cytokinetic terms as a unique form of squamous cell carcinoma. This low-grade malignant lesion has distinct clinical and pathologic features, distinguishing it from other well-differentiated squamous cell carcinomas . Since verrucous carcinoma was first identified as a distinct clinicopathologic entity, there has been great confusion in the literature as to the appropriate therapeutic approach, the incidence of recurrence, and the frequency of anaplastic transformation of this carcinoma.
Current concepts about the management of this uncommon tumor as well as some recent investigations that deal with its etiology and molecular genetic alterations were reviewed.
In the treatment of this tumor, although there is no doubt that complete surgical excision is the treatment of choice, this may be precluded by the patient's medical status, the extent of the lesion, or both. Despite the fact that this is a moderately radiosensitive lesion, radiation therapy has generally been condemned because of the increased risk of anaplastic transformation and high rate of recurrence. However, recent studies demonstrated that oral verrucous carcinoma has similar radioresponsiveness and improved survival compared to well-differentiated squamous cell carcinomas. Radiation therapy may be an effective alternative if surgical treatment is contraindicated.

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Fifty-three patients with gingival carcinomas treated by surgery after preoperative chemotherapy were studied with respect to clinical and histopathological significance of preoperative chemotherapy based on the results of treatment and by histologic grading of malignancy. The results were as follows:
1. There was no significant difference in the effects of preoperative chemotherapy between patient groups classified by clinical findings or histological differentiation of carcinomas, while preoperative chemotherapy was more effective and therapeutic results were better in patients with lower and moderate histological malignancy than with high malignancy.
2. As a result of preoperative chemotherapy, grade of each histological malignancy evaluation parameter tended to decrease. Better results were obtained with respect to the five-year survival rate and metastatic rate in patients showing decreased malignancy after preoperative chemotherapy.
3. The results suggested that preoperative chemotherapy is effective for treatment of gingival carcinomas with low histological malignancy and may contribute to better therapeutic results.
4. The presence or absence of epithelial dysplasia in the surgical margin was added to the conventional parameters of histologic grading of malignancy, and evaluation was done. As a result, the outcome of gingival carcinomas was poor when the scores of the mode of infiltration and surgical margin were high.

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Three human oral squamous cell carcinoma cell lines (HSC-2, 3 and 4), both in the form of single cell suspension and tissue, and seven cancer tissues obtained by operation (KOS-4, 5, 6, 7, 8, 9 and 10) were transplanted to the tongue of nude mouse. A histologic study was conducted to examine local invasion and lymph node metastasis in this animal model, and the results were as follows
1) Each material was transplanted to the tongue of nude mouse with the success rate of 29% to 100%.
2) Histologic examination of the transplanted tumor revealed invasive proliferation in the tongue of nude mouse. There were no apparent differences between the histologic features of single cells and those of cancer tissue.
3) Mode of invasion of the transplanted KOS-4-10 tumor in the tongue of nude mouse was similar to that of the patient from whom the material was obtained.
4) Metastasis to the cervical lymph node was observed in animals to which HSC-2, HSC-3, HSC-4, KOS-5, KOS-7 and KOS-8 were transplanted. The metastasic rate was 13% to 80%.
5) These findings indicated that this experimental model was useful in animal studies of local invasion and lymph node metastasis of oral cancer.

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To evaluate accuracy of the intraoperative rapid frozen section diagnosis in assessing malignancy and margins, 71 frozen sections obtained at the time of excisional biopsy for oral squamous carcinomas were examined.
There were two false-negative cases when the frozen section diagnosis was compared with the final diagnosis on permanent sections, including five cases of carcinoma in situ and 66 cases of invasive squamous cell carcinoma. Thus 97.2 % of accuracy was found in the frozen section diagnosis. 78.7% of accuracy was found in grading histological differentiation and 80.0% accuracy in assessing pericancerous epithelial dysplasia. On the other hand, in grading the mode of invasion, 62.3% of accuravy was found between frozen section and permanent section. In diffuse type of mode of invasion, however, it should be kept in mind that it could be graded lower in the frozen section than the permanent section.
Local recurrence related to margin status in the permanent sections but not in the frozen sections. However, frozen section diagnosis is useful to obtain surgical-free margins.

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The purpose of this study was to evaluate ultrasonographic findings of extracapsular invasion. Ultrasonography of 61 metastatic lymph nodes (37 patients) from oral squamous cell carcinoma performed between 1987 and 1997 were compared with pathological findings retrospectively.
Capsule of the stage IV lymph nodes, which were histologically confirmed to have extra capsular invasion, was thin, while that of stage III lymph nodes, which predominantly had a metastatic lesion, was thick. Stage IV lymph nodes tended to have irregular margin and stage III lymph nodes tended to have enhancement of bottom echo or appearance of halo on ultrasonographs.
These results suggested that enhancement of bottom echo and appearance of halo on ultrasonographs indicate a thick capsule of metastatic lymph nodes, and that the presence of irregular margin indicate the wide extra capsular invasion of the metastatic lymph nodes.

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When the T-classification of UICC (1987) is simply applied to carcinomas of the upper alveolus and gingiva and the hard palate, most of the cases are classified as T4 due to its anatomical characteristics, just like those of carcinomas in the lower alveolus and gingiva. In the present study, the following three methods were applied for T4 criteria : 1) the original T-classification criteria of UICC (1987) ; 2) the criteria of the Japanese Association for Head and Neck Tumors ; and 3) the new T-classification criteria, the so-called sinus and nasal floor criteria. Then their appropriateness for clinical use were compared. The results showed that the T-classification criteria of sinus and nasal floor method was the most appropriate in T-distribution, the relationship with prognosis, and clearness.

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To find predictive indicators for distant metastasis, clinico-pathological findings in patients with squmous cell carcinoma of the oral cavity were investigated.
Records of 535 patients with squamous cell carcinoma of the oral cavity, treated in our departments between 1974 and 1995, were reviewed. One hundred eight patients with locoregional failure were excluded in this study. Of the 427 patients locoregionally controlled, 112 cases were found to have pathologically positive neck nodes, and the others had clinically and/or pathologically negative nodes. The incidence of distant metastasis in these group were 22.3% and 1.6%, respectively. There was a significant difference in the incidence between the two groups (p< .001) . Therefore, the presence of neck node metastasis was found to be one of the critical factors that influence the development of distant metastasis.
In order to find additional critical factors for distant metastasis, clinico-pathological findings in 112 patients were investigated by multivariate analysis. According to multiple logistic regression analysis, odds ratio of the level was 3.960. Lower neck involvement may be a decisive factor in a patient treated aggressively.

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Maxillof acial prosthetic treatment using Epitec System was performed after treatment of a malignant tumor in the oral and maxillof acial region.
Epitec System (Leibinger, Germany) is different in shape from other types of maxillof acial osseous implants and it was developed from a titanium plate originally for fractured jaws. A 1mm thick cross-striped titanium plate was adapted to the bone around a defect and fixed with 2mm diameter titanium screws. Three months or more after the placement of the plate, the post to penetrate skin or mucosa is screwed into the hole left by removal of a sleeping screw, and abutment was placed on the other side.
Maxillof acial prostheses (epitheses) were set in three patients with defects in this region due to tumor resection. In case 1, the progress of the tumor was favorable giving satisfactory support and stability to the epitheses. But in case 2, tumor recurrence was found six months after the prosthetic treatment : the prosthesis and titanium plate could be removed in minimum surgical violation. In case 3, simultaneous placement of the plate at the tumor resection was performed in an attempt to achieve functional restoration at an early stage.
Epitec System has advantages in maxillof acial prosthetic treatment over other alternatives. For example, it is adaptable in case of thin bone, maintains the epithesis in an ideal position, and surgical invasion is minimal at the time of its placement and removal.

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WHO Histological Typing of Odontogenic Tumors was revised in 1992, and a section of unicystic ameloblastoma was added.
A 37-years-old male had a cystic lesion in the premolar region of the mandible, and a 67-years-old male had a lesion suspected to be ameloblastoma in the molar region of the mandible. The radiographic findings showed unilocular and multilocular radiolucent lesion with a smooth margin, respectively. These lesions were treated by enucleation. Histopathological findings revealed that these lesions were type II and type I unicystic ameloblastomas, respcectively. There has been no recurrence in these cases.
Fourteen cases of unicystic ameloblastoma reported in literatures and these 2 cases were reviewed clinicopathologically.

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Two patients with Swing's sarcoma of the jaw were reported.
Case 1 was a 7-year-old female with the chief complaints of an expanding mass and pressure pain of the right mental region. The clinical diagnosis was osteogenic sarcoma, but histopathologically Ewing's sarcoma. The tumor of the mental region was 38×30 mm in size. Mandibular resection following preoperative chemotherapy of MTX and doxorubicin [AD] was carried out. In spite of the postoperative radiotherapy of ⁶⁰Co 27Gy with administration of vincristine [VC], actionomycin D [AC] and cyclophosphamide [CP], she died due to brain metastasis 10 months later.
Case 2 was a 2-year-old male with the chief complaint of a swelling in the anterior region of the maxilla. The tumor located in the bilateral incisal region of the maxilla was 27×34mm in size. The clinical diagnosis was suspicted malignant tumor, and histopathologic examination revealed Ewing's sarcoma. The patient was treated by irradiation of ⁶⁰CO 35Gy with chemotherapy of VAC regimen [VC, AC, CP] . He died due to pulmonary metastasis 4 years and 2 months after the initial diagnosis.
Both patients with primary lesion of upper and lower jaws had been well controlled clinically, but died because of uncontrollable distant metastases.

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