Yoshihide Ota

Pneumomediastinum and subcutaneous emphysema after dental extraction detected incidentally by regular medical checkup: a case report.

Most cases of pneumomediastinum are caused by iatrogenic injury during surgery on the cervical region and chest or by tracheostomy. It is also well known that emphysema may occur secondary to dental treatment using an air turbine drill, but there have been few cases of emphysema extending to involve the mediastinum. Presented is a rare case in which subcutaneous emphysema and pneumomediastinum developed asymptomatically, probably due to extraction of a mandibular third molar, and were found incidentally on the day after the dental procedure. To avoid subcutaneous emphysema and pneumomediastinum associated with dental treatment and surgical intraoral procedures such as tooth extraction, air turbine drills should be used only when it is essential.

Schwannoma of the mental nerve: usefulness of preoperative imaging: a case report

Schwannoma of the head and neck region is relatively uncommon. We report a case of schwannoma arising from the left mental nerve. A 21-year-old male presented at our hospital with a painless swelling of the left cheek. Because the lesion had rapidly increased in size, a malignant tumor was suspected. Magnetic resonance imaging (MRI), computed tomography, and ultrasonography were performed. MRI and ultrasonography revealed that the tumor was connected to the mental nerve. Both MRI and ultrasonography were found to be useful in making a preoperative diagnosis. It was possible to determine prior to surgery that this was a peripheral nerve sheath tumor. The lesion was completely resected. The pathological diagnosis was Antoni type A schwannoma. There has been no sign of recurrence 1 year after surgery.

Ameloblastic carcinoma, secondary type: a case report

Malignant variants of ameloblastoma include metastasizing ameloblastoma, which microscopically appears benign but has metastasized and ameloblastic carcinoma that exhibits malignant histopathologic features. Ameloblastic carcinoma is classified into 2 types: a primary odontogenic malignancy and a secondary type resulting from malignant transformation of ameloblastoma. Most secondary ameloblastic carcinomas result from malignant transformation of a primary lesion after repeated postsurgical recurrences. Therefore it is rare to find an untreated secondary type presenting with histologic features of malignant transformation from an earlier benign lesion. We experienced a rare case of ameloblastic carcinoma, secondary type which might arise in an untreated ameloblastoma. The mechanism by which a preexisting benign ameloblastoma goes through a malignant transformation is also described.

Stem cell self-renewal factors Bmi1 and HMGA2 in head and neck squamous cell carcinoma: clues for diagnosis

Head and neck squamous cell carcinoma (HNSCC) includes both morphological and functional cellular heterogeneity, as would be expected if it arose from dysregulated stem or progenitor cells as opposed to the simple clonal expansion of a mutated cell; however, stemness molecule expression levels and distribution in HNSCC remain unclear. To clarify this, stemness molecule expressions were determined in HNSCC, as well as their properties and prognosis. Two proto-oncogenic chromatin regulators, Bmi-1 and high-mobility-group A2 (Hmga2), were identified in 12 pair cases of HNSCC tumor regions by comparison with their non-cancerous background tissues using cDNA microarray. Both Bmi-1 and Hmga2 are known to promote stem cell self-renewal by negatively regulating the expressions of Ink4a and Arf tumor suppressors. Despite similar targets, Bmi-1 protein was expressed in an early cancerous region and HMGA2 protein was expressed in a region showing more progression. Similarly, Bmi1 expression had no significance with regard to overall survival (P=0.67), whereas HMGA2 expression was associated with decreased overall survival (P=0.05). Quantitative real-time reverse transcription polymerase chain reaction analyses also correlated with protein levels. These findings suggest that Bmi-1 is an early detection marker to distinguish cancerous from non-cancerous regions, whereas HMGA2 is presumed to be a tumor prognosis marker. Among our HNSCC analyses, these stemness molecules expressed fewer primitive rare cells in the tumor than all other cells in the tumor. HNSCC cells with high expression of stemness molecules partly behave like stem cells.

Bilateral numb chin syndrome leading to a diagnosis of Burkitt's cell acute lymphocytic leukemia: a case report and literature review

Numb chin syndrome (NCS), also known as mental nerve neuropathy, is characterized by facial and oral numbness restricted to the distribution of the mental nerve. Although not a common neuropathy, the clinical importance of this syndrome is its frequent association with malignancies, particularly breast cancer and lymphoma. In this paper, we present a rare case of Burkitt cell acute lymphocytic leukemia initially presenting with bilateral NCS. In this case, no abnormalities were detected on initial blood tests and radiologic investigations except for partial loss of lamina dura around mandibular teeth. Furthermore, we found no evidence of any other signs of central nervous system involvement apart from NCS. Nevertheless, the patient continued to experience severe bilateral mandibular pain and paresthesia, prompting us to repeat the blood studies. These showed lymphomatous cells, yielding the diagnosis of leukemia 37 days after the original presentation. When a patient presents with the extremely unusual symptoms of bilateral numbness of lower lip and chin, we should suspect the presence of a malignancy even in the absence of any relevant past history. If the initial radiologic investigations and blood tests reveal no abnormalities, malignancy should not be removed from the differential diagnosis until a definite cause has been found.

Determination of deep surgical margin based on anatomical architecture for local control of squamous cell carcinoma of the buccal mucosa

Of all oral squamous cell carcinomas, squamous cell carcinomas of the buccal mucosa (BSCC) are most associated with poorest prognosis. In particular, patients treated with surgery alone are reported to experience frequent local failures. This is considered to result from the surgeons determination of the deep surgical margin for resection based on palpation alone when performing BSCC surgery. Therefore, an objective system for classifying the depth of invasion of a tumor appears to be necessary in order to improve the results of BSCC treatment. While current general practice is to treat based on tumor thickness, we would like to emphasize the importance of how far down the cheek wall layer the tumor has invaded. We performed surgery by classifying the depths of tumor invasion in relation to the buccinator. Depth of tumor invasion was assessed mainly using ultrasonography (US). The tumor was defined as D1 when it extended to the mucosal (m) and submucosal layers (sm). In these cases, the tumor was resected, while the buccinator was spared. The tumor was defined as D2 when it extended to the buccinator, but, based on US, muscle continuity was preserved, and the tumor was resected to include the buccinator and its overlying fascia. When the tumor had spread to the buccinator or invaded subcutaneous or cutaneous tissue it was classified as D3 and resection included the skin. The disease-specific survival rate of BSCC when treated based on our classification was 73.7% and the local control rate was 89.5%. These results are superior to those based on surgery alone and this therapeutic modality was considered to be useful.

Association of hepatocyte growth factor expression with salivary gland tumor differentiation.

To clarify the significance of hepatocyte growth factor (HGF) expression in salivary gland tumors, HGF distribution in tissue sections and HGF concentrations in saliva and serum were examined. Sixty salivary gland adenomas, 61 salivary gland carcinomas and three autopsy fetuses were studied. Hepatocyte growth factor expression was observed in the duct‐type luminal cells by immunohistochemical staining and in situ hybridization. However, HGF failed to be expressed in acinar cells and myoepithelium of normal salivary gland tissue. Hepatocyte growth factor tended to be expressed more intensely in benign salivary gland tumors than in malignant salivary gland tumors (P < 0.0001). In highly malignant tumors, the expression was limited in some cases. Salivary and serological HGF concentrations of 18 patients, comprised of 12 benign cases and six malignant cases, were analyzed before and after operation by an ELISA system. The concentrations were distinctly elevated after operation, in both saliva and serum, compared to before operation (P < 0.0005). However, there were no significant relationships between HGF concentration and histology, age, gender, size or location. Our findings suggest that HGF may play an important role in the development of salivary ducts of normal salivary tissues and differentiation of ductal structures of their neoplasms, while HGF kinetics in saliva and serum would be less likely to reflect the neoplastic character, benign or malignant.

Postoperative follow-up strategy in patients with oral squamous cell carcinoma.

PURPOSE The duration of follow-up after treatment of oral squamous cell carcinoma and the frequency of routine visits are based on common usage rather than evidence-based practice. The purpose of this study was to determine the appropriate postoperative routine follow-up program in patients with oral squamous cell carcinoma. PATIENTS AND METHODS Three hundred four cases treated curatively mainly by surgery at Tokai University Hospital from 1994 to 2004 were analyzed. A secondary event was defined as a local recurrence, a regional recurrence, a distant metastasis, or a second primary cancer. To evaluate the follow-up program, data on the first tumor recurrence or first second primary tumor in the head and neck region or elsewhere in the body were used. Overall survival rate, disease-specific survival rate, relapse-free rate, and cumulative risk of developing a second primary cancer were estimated by the Kaplan-Meier product limit method. RESULT All relapse cases were detected within 3 years postoperatively, of which 86.3% were detected within 1 year. Most relapses were in the neck, and regional recurrences had a dismal salvage rate. Second primary cancers were constantly detected 1 to 10 years postoperatively. CONCLUSION Follow-up should be performed more frequently in the first year, with 2 weekly follow-ups with monthly ultrasound examinations, and should be continued after 3 years to exclude the development of second primary cancers.

Frequent mutations in NOTCH1 ligand-binding regions in Japanese oral squamous cell carcinoma.

Recent studies showed that head and neck squamous cell carcinoma (HNSCC) including oral squamous cell carcinoma (OSCC) of Caucasian, Chinese and Indian patients frequently have NOTCH1 mutations. We found eight of 84 OSCC in Japanese patients have point mutations (9.5%) correspond to the ligand binding region of NOTCH1 protein. Two set of them are the same mutations and all mutations are non-synonymous G>A transitions. In addition, median disease-free survival is significantly longer in patients with NOTCH1-mutated tumors as compared to those without the mutation (P<0.05). The protein structure simulation based on X-ray crystallography indicated that new p.A465T mutation leads to a conformational change of NOTCH1 ligand binding domain as well as the p.G481S mutant NOTCH1 with a loss of flexibility around this residue. These results suggest that NOTCH1 mutation occurs frequently in Japanese OSCC in the vicinity of the ligand binding region and, these mutations cause downregulation of the NOTCH1 function.

Lung Metastases of Epithelial-Myoepithelial Carcinoma of the Parotid Gland Successfully Treated With Chemotherapy: A Case Report

Salivary gland malignancy is a relatively rare disease of various histologic types, and no standard chemotherapeutic drugs or regimens have yet been established for the treatment of individual types of salivary gland carcinomas. Among salivary gland malignancies, epithelial-myoepithelial carcinoma (EMC) is a rare tumor entity of intermediate-grade malignancy. 1,2 Distant metastases of EMC have been described in the organs, including the lungs, kidneys, and brain. 2-5 This report describes our recent experience with a case of primary EMC of the parotid gland treated with total parotidectomy and adjuvant radiotherapy, followed by onset of lung metastases treated with chemotherapy leading to complete response (CR).