Human papillomavirus (HPV) infection in oral squamous cell carcinomas were studied by the polymerase chain reaction, immunohistchemical analysis and in situ hybridization. There were no significant differences in HPV prevalence for oral squamous cell carcinoma concerning age, sex, location and histlogical grades. However, the results of this study suggested that high prevalence of several HPV types, such as HPV-22, 38 and 70, were frequently detected in oral squamous cell carcinomas, indicating that HPV infection may be associated with the occurrence of oral squamous cell carcinoma.

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Tumor metastasis to the oral cavity is very rare. Therefore, differential diagnosis of metastatic tumors and primary tumors in the oral cavity is frequently difficult. In the present study, we clinically examined seven cases of metastatic tumor to oral cavity, and compared clinical findings of our cases with previous reports.
Metastatic sites in the oral cavity were two cases in the maxilla, one case in the upper gingiva, and four cases in the mandible. Primary organs of the metastatic tumors were lung in three cases, and one case for each of prostate, colon, liver, and skin of the lower limbs. Histological diagnoses of the metastastic tumors were four cases of adenocarcinoma, two cases of squamous cell carcinoma, and one case of malignant melanoma. Clinical manifestation were two cases of painful swelling, four cases of painless swelling, and one case of a painless tumor. Time till metastasis to the oral cavity after primary treatment was within five months in four cases, nine months in one case, and 10 years in one case. In one case, the metastatic tumor was found before the primary tumor. Only two cases of metastatic tumors in the oral cavity were treated ; the other cases were not treated. Prognosis of the metastatic tumors was very poor, and five of the seven patients died within eignt months after metastasis to the oral cavity.
These results suggest that it is nesessary to differentially diagnose and to carefully examine for tumor metastasis to the oral cavity.

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Malignant melanoma of the mucous membranes is rare, and the prognosis is very poor. Treatment for this disease has not yet been established. We tried immunotherapeutic treatment for a case of amelanotic malignant melanoma, with interferon-β, and the tumor temporarily responded. The patient was a 70-year-old male with complaints of swelling, pain, and bleeding in the upper right gingiva, and swelling of the right submandibular region. On inspection, a soft irregular mass occupied the upper rightgingiva, and also the right submandibular lymph node was enlarged, and metastasis was suspected. A biopsy of the upper gingiva led to a diagnosis of amelanotic malignant melanoma. After a local continuous intraarterial infusion of high-dose interferon-β (total 118 days 35, 900×10⁴IU), the tumor in the oral region had disappeared, and the submandibular lymph node was reduced significantly.

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Tongue cancer in persons under age 20 has been rare, and its treatment remains unclear. It is important to discuss not only its treatment but also its complications. In addition, a cooperation of the family is necessary concerning the truth and informed consent, because the patients young adults. A rare case of tongue cancer arising in an 18-year-old patient is reported. An 18-year old male, who had contact pain on the right tongue rim, was referred to our department on March 14, 1998. A 15×10 mm painful mass with an ulcer was found on the right side of the tongue rim. A tongue biopsy revealed moderately differentiated squamous cell carcinoma (T1N0M0) . A combination of surgery and chemotherapy (CDDP, PEP) was carried out, to reduce the postoperative dysfunction of the tongue. The patient had good local control without serious dysfunction of the tongue. One year later, total neck dissection on the right side was performed, for metastasis to a cervical lymphnode. There has been, at the present time, no evidence of recurrence or metastasis in the patient, at about 13 months after the total dissection operation. However, his parents told him the truth which has been cancer without our consent because he had serious mental problems. Therefore, it is important to treat mental problems that may involve the young adult patient and his family.

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This report describes a case of papillary cystadenocarcinoma of the tongue. Papillary cystadenocacinoma is a rare disease newly added to the WHO classification of salivary gland neoplasms in 1991. And it is a malignant tumor with a papillary growth pattern in a cystic structure.
The patient was a 50-year-old woman. Clinically, a minor salivary gland tumor of the tongue was the diagnosis for a small mass on the right-side lingual edge, so a partial excision of the tongue was performed. The histopathological diagnosis was papillary cystadenocacinoma. Postoperative external irradiation (total 55.6Gy) was performed to the perif ocal tissue, because infiltrative growth and lymph vessel invasion were found in the circumference. Present in postoperative about 1 year, the opinion which suspects recurrence and metastasis is not found.
We report on the therapy and prognosis with a literary consideration.

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When a cell is exposed to high-voltage, short electric pulses, the cell membrane can be opened transiently without causing permanent cell damage. This process is referred to as electroporation. Electroporation has been used to introduce the anticancer drug, bleomycin (BLM), into living cells. The new method of cancer treatment that combines electroporation and a chemotherapeutic agent has been named electrochemotherapy (ECT) . We evaluated the effects of ECT with intratumoral injection of BLM in a chemically induced gingival cancer model, in the hamster.
In this study, each electrical treatment regimen for ECT consisted of eight triangular direct current pulses with a width 99μs and a frequency of 1 Hz. Electric field strength, defined as the voltage applied to the electrodes divided by the distance between the electrodes placed on either side of the tumor, was 130V/mm. Electrical energy was transmitted through a pair of parallel plate electrodes or needle electrodes. Electrical treatment was performed immediately after intratumoral injection of BLM.
After a week, all animals that received ECT showed tumor volume reduction, while no antitumor effects were observed in the control groups. Although after two weeks the animals that received ECT using parallel plate electrodes showed regrowth of the tumor, the animals that received ECT using needle electrodes showed continuous tumor volume reduction, and one of six animals showed complete response after three weeks. These results indicated that ECT enhanced the antitumor effect of BLM. In particular, a needle electrode was more effective than a parallel plate electrode in a hamster gingival cancer model.

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Electrochemotherapy (ECT) is a new technique that enhances the antitumor effect of various anticancer agents by delivering high-voltage electrical impulses to the tumor. In the present study, ECT was used in the treatment of oral cancer using SCC158 cell, a rat squamous cell carcinoma, which was transplanted into the tongue. These tumors were subjected to high-voltage electrical impulses (1200V/cm, 0.1msec, 8 pulses) 30 minutes after the injection of bleomycin. The antitumor effect of ECT on these tumors was then evaluated, as were histological changes in the damaged tumor, and healing of the surrounding damaged tissue. In a further experiment, to determine the optimum voltage of electrical impulse histologically, these tumors received various electrical pulses (125-1200V/cm, 0.1msec, 8 pulses) in ECT.
As a result, the tongue tumors were no longer visible from the 3rd day after ECT, and histological examination revealed complete regression. The healing following ECT proceeded in an almost uneventful manner, but the normal tissue within the electrical field was necrotic. In addition, the antitumor effect of ECT appeared most strongly when the voltage was more than 1000V/cm ; however, the surrounding normal tissue within the electrical field was seriously damaged.
In conclusion, ECT was shown to be an efficient therapy for treating tumors of the tongue, and it is expected to be applied to human oral cancer. It is hoped that problems related to damage to normal tissue and the inducement of metastasis will soon be resolved as a result of future investigations.

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Electrochemotherapy is a new antitumor treatment that delivers electrical pulses to the tumor site, several minutes after injection of antitumor chemical agents. In this study, oral fibrosarcoma was submucosally transplanted into the cheek pouch mucosa in 280 hamsters. When the tumor size was approximately 300mm³, these hamsters were randomly divided into 4 groups, each group consisting of 20 hamsters. At this time, treatments were initiated. All groups were treated as follows
The animals of the D^-E^- group (control group) received no treatment. The animals of the D^-E⁺ group received electric pulses without anticancer drug injection. The animals of the D⁺E^- group received each six anticancer drugs : bleomycin (BLM), etoposide (LAS), cyclophoshamide (CPA), cisplatin (CDDP), doxorubicin (ADR) and 5FU, by injection only. The animals of the D⁺E⁺ group received electric pulses across the tumor for 30 minutes after an intraperitoneal injection of BLM, LAS, CPA, CDDP, ADR, and 5FU.
Electric pulse treatment together with each of BLM, LAS, CPA, and CDDP injection markedly reduced the tumor size. However, these anticancer drug injections alone, or electric pulse treatment alone, did not reduce the tumor size. These results clearly indicated that the antitumor effects of BLM, LAS, CPA, and CDDP on the lesion of hamster oral f ibrosarcoma could be considerably potentiated or enhanced by local electric pulses.

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Electrochemotherapy is a novel chemotherapeutic strategy to potentiate cytocidal effects of anticancer agents by means of electroporation. In the present study, weexamined the optimal condition of electric impulses (EI) in in vitro study.
In vitro electrochemotherapy was performed by delivering various EI, changing the field intensity, pulse duration, and frequency, to a cell suspension immediately after adding bleomycin (BLM) solution. Cytocidal effects were assessed by MTT assay. In addition, an intracellular concentration of BLM was evaluated by means of bioassay in electreporated and non-electroporated cells.
Cytotoxicity of EI themselves was seen only when the intensity of the electric field was raised up to 1200V/cm. The viability of pulsed cells was significantly decreased as the field intensity was increased. The potential effect of cytotoxicities of these agents was evident when the condition of EI was over 4 pulses of 80 to 100μsec at a field intensity of more than 400V/cm. This phenomenon was most prominent with an increase in field intensity, which was greatly concerned with electric energy. The increase of the intracellular concentration of the drug in pulsed cells seems to be consistent with a pootential anticancer effect.

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Treatment of renal cell carcinoma (RCC) with a combination of electrical impulses and bleomycin (BLM) resulted in great efficacy of tumor cell killing, in in vivo experiments. An application of high-voltage electrical impulses to tumors, after injection of Bleomycin, resulted in their disappearance within 4 days in renal cell carcinoma-bearing mice. Such complete regression was achieved at a single bleomycin dose of 1/10 of the LD₅₀, when combined with electrical pulses. However, the tumor regrow again after day 11. Other drugs. such as CDDP, 5-FU, MMC, and Vinblastin, showed no retardation of tumor growth. This electrochemotherapy induced apoptotic cell death in RCC. The concomitant use of high-voltage electrical impulses has the potential to increase the efficacy of Bleomycin treatment of renal cancer, as reflected in a substantial reduction in tumor growth.

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We report three cases of an osteocartilaginous mass in the temporomandibular joint, which each had characteristics in pathology and treatment.
Case 1 : A 52-year-old woman had a large bony mass stalked at the medial surface of the right condyle and extending superiorly towards the cranial base. A vertical osteotomy was carried out, and the posterior part of the ramus and condyle was removed. Excision of the mass was performed on the table, with inclusion of one-third of the normal condyle. The condyle was immediately repositioned into the glenoid f ossa, using rigid fixation. The specimen measured 3×25×15mm in size and histologically showed osteochondroma. Four-year postoperative radiographs showed no relapse.
Case 2 : A 36-year-old woman was referred for a bony mass on the right tuberosity of the temporomandibular joint. The mass was excised, and the surface of the tuberosity was ground away, without perforation of the cranial base. The specimen measured 23×17×12mm in size and histologically showed osteochondroma. No relapse was found at three-year postoperative follow-ups.
Case 3 : A 26-year-old woman visited our clinic because of severe pain of the left temporomandibular joint. MRI revealed many small loose bodies in the upper joint space. Our newly developed arthroscope, which has a treatment channel in it, was inserted into the space. A total of 340 loose bodies were removed through the channel. These were histologically diagnosed as chondromatosis. After the surgery, the pain decreased, and no relapse was found at two-year postoperative follow-ups.

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Tumors and tumor-like lesions that involve the temporomandibular joint (TMJ) are very rare and often diagnosed late because of unspecif is or misinterpreted symptoms, which occasionally may lead to extensive expansion of the lesions. Although many reports of TMJ tumors and tumor-like lesions have appeared in the literature, in most of these reports, the bony lesions were either isolated condylar lesions or lesions affecting most of the ascending ramus of mandible.
Two osteolytic lesions extended through the eminence or the glenoid fossa of the temporal bone to the middle cranial f ossa are reported. One was diagnosed as an eosinophilic granuloma arising from the eminence of the temporal bone, and the other was diagnosed as synovial chondromatosis with intracranial extension. We believe that the former is the first case of eosinophilic granuloma arising from the eminence expanded to the middle cranial fossa. Because only 7 cases of intracranial extension of synovial chondromatosis of the TMJ have been previously reported, the latter case may be the eighth case of synovial chondromatosis with intracranial extension. An overview of the current literature and a discussion of the differential diagnosis of the osteolytic lesions extended through the eminence or the glenoid fossa of the temporal bone.

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We reported a case of chondroblastoma that arose in the left mandibular condyle. Including the case presented here, only 5 cases of chondroblastoma of the condylar process of the mandible had been reported in the past 30 years.

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A rare case of synovial chondromatosis associated with osteochondroma of the mandibular condyle, in a 41-year old female, is presented. The patient's chief complaint was facial asymmetry. Radiographic and CT diagnostic images revealed several loose bodies adjacent to a hypertrohic mandibular condyle on the right side. Surgical findings disclosed no abnormalities in the upper joint space, though the lesion was inspected only in the lower compartment. High condylectomy with diskectomy and the removal of seven loose bodies were cawied out. postoperative course is uneventjul.

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Malignant tumors of the temporomandibular joint (TMJ) are extremely rare. They are classified into three types : tumors primarily arising from the TMJ, tumors of neighboring tissues directly extending to the TMJ, and metastatic tumors to the TMJ.
Clinical symptoms associated with malignant tumors are similar to those of other TMJ disorders, but they are more progressive.
Various diagnostic imaging modalities, such as CT, MRI, and ^99mTc and ⁶⁷Ga scintigraphy, should be employed to determine the extent of the disease, in addition to a careful review of the patient's medical history and clinical examination. To establish the diagnosis, fine needle aspiration cytology (FNAC) or open biopsy is mandatory. In particular, echo-guided FNAC is preferable to open biopsy, because of its easy and safe technique.
Wide local resection is the treatment of choice for primary tumors. A transparotid approach to the ascending ramus of the mandible is useful for complete resection of malignant tumors of the TMJ. Radiotherapy, chemotherapy, or surgery alone or in combination is usually selected for extending and metastatic tumors. However, as the treatment of metastatic diseases generally carries a poor prognosis, the patient's quality of life (QOL) should be considered when planning treatment.

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