Recurrent cementoblastoma with multifocal growth and cellular atypia: a case report

BACKGROUND

Cementoblastoma is a rare odontogenic tumor characterized by the formation of osteocementum-like tissue on a tooth root directly by neoplastic cementoblasts. Although it is categorized as benign, it has a high potential for growth with a certain degree of recurrence risk. However, there are only a few studies describing the features of recurrent cementoblastoma. The diagnosis of recurrent cementoblastoma is challenging not only due to its cytological atypia but also because of its large size and multicentric growth pattern. These characteristics suggest a potential for malignancy.

CASE PRESENTATION

A 29-year-old woman was transferred to our university dental hospital complaining of swelling of the right mandible. She had a history of enucleation of cementoblastoma associated with the third molar of the right mandible. Five years after the initial treatment, imaging demonstrated well-circumscribed multicentric radiopaque lesions in the same area. Histologically, the lesion consisted of osteocementum-like tissue rimmed with polygonal or plump tumor cells. Several cells were large epithelioid cells with bizarre nucleoli, which may be reminiscent of malignant tumors. Otherwise, there were no apparent malignant findings, including proliferative activity or atypical mitotic figure. Besides, tumor cells were positive for c-FOS, a marker of osteoblastoma and cementoblastoma. Eventually, the patient was diagnosed with recurrent cementoblastoma.

CONCLUSIONS

Pathological analyses of this case suggested that the recurrent event in the cementoblastoma altered its growth pattern and tumor cell shape. Moreover, in the case of enucleation surgery, long-term follow-up is important because there is some recurrent risk of cementoblastoma, although it is not high.

Risk factors for impacted lower third molar root perforation through the undercut-shaped lingual plate: preoperative insights from panoramic radiography

This study aimed to identify risk factors associated with perforation of the undercut (U)-shaped lingual plate (LP) by the lower third molar (LM3) root using panoramic radiography (PAN). We retrospectively examined 468 impacted LM3s from 468 individuals, categorizing LM3-LP associations and LP morphology in the coronal section of cone-beam computed tomography as perforation or nonperforation and U-type or non-U-type, respectively. The outcome was the combination of perforation and U-type, and study variables included patient demographics (age and sex) and PAN-associated features (Winter's classification, Pell-Gregory classification, and two major Rood signs). Multivariate logistic regression methods were used for analysis. Perforated and U-type LPs were observed in 205 (43.8%) and 212 (45.3%) cases, respectively. The double-positive outcome was observed in 126 LM3s (26.9%). In the multivariate model, age ≥ 26 years [odds ratio (OR), 2.66; p = 0.002], men (OR, 2.01; p = 0.002), mesioangular (OR, 2.74; p = 0.038) and horizontal impaction (OR, 3.05; p = 0.019), and root darkening (OR, 1.73; p = 0.039) were independently associated with the risk. Class III impaction (OR, 0.35; p = 0.021) and interruption of the white line (OR, 0.55; p = 0.017) were negatively correlated with the risk. In conclusion, this study highlights the importance of identifying the higher probability of U-type LP perforation by the LM3 root in men aged over their midtwenties with Class I/II impaction and mesioangularly or horizontally impacted LM3s, along with root darkening and no interruption of the white line on PAN.

Transcriptomic analysis of Porphyromonas gingivalis-infected head and neck cancer cells: Identification of PLAU as a candidate prognostic biomarker

Periodontal disease is a risk factor for head and neck squamous cell carcinoma (HNSCC), and Porphyromonas gingivalis, a major periodontal pathogen, has been identified as a specific and potentially independent microbial factor that increases the risk of cancer mortality. Gene expression in HNSCC due to P. gingivalis infection and how changes in gene expression affect the prognosis of HNSCC patients are not clarified. When P. gingivalis was cultured with HNSCC cells, it efficiently adhered to these cells and enhanced their invasive ability. A transcriptome analysis of P. gingivalis -infected HNSCC cells showed that genes related to migration, including CCL20, CITED2, CTGF, C8orf44-SGK3, DUSP10, EGR3, FUZ, HBEGF, IL1B, IL24, JUN, PLAU, PTGS2, P2RY1, SEMA7A, SGK1 and SIX2, were highly up- or down-regulated. The expression of up-regulated genes was examined using the expression data of HNSCC patients obtained from The Cancer Genome Atlas (TCGA) database, and the expression of 5 genes, including PLAU, was found to be higher in cancer tissue than in solid normal tissue. An analysis of protein-protein interactions revealed that these 5 genes formed a dense network. A Cox regression analysis showed that high PLAU expression levels were associated with a poor prognosis in patients with TCGA-HNSCC. Furthermore, the prognostic impact correlated with tumour size and the presence or absence of lymph node metastasis. Collectively, these results suggest the potential of PLAU as a molecular prognostic marker in HNSCC patients. Further in vivo and in vitro studies are needed to verify the findings of this study.

Clear Cell Squamous Cell Carcinoma of the Maxillary Gingiva Associated with PIK3CA and HRAS Mutations: Report of a Case and Literature Review

BACKGROUND

Squamous cell carcinoma (SCC) is the most common oral malignancy, and somatic mutations in some driver genes have been implicated in SCC development. Clear cell SCC (CCSCC) is a rare histological variant of SCC, and various clear cell neoplasms must be considered in the differential diagnosis of CCSCC in the oral cavity. Based on a limited number of CCSCC cases reported in the oral cavity, CCSCC is considered an aggressive variant of SCC with a poor prognosis; however, its genetic characteristics remain unknown.

METHODS

A maxillary gingival tumor in an 89-year-old female was described and investigated using immunohistochemical staining, special staining, fluorescence in situ hybridization, and next-generation sequencing (NGS) with a custom panel of driver genes, including those associated with SCC and clear cell neoplasm development.

RESULTS

Histopathological examination revealed a proliferation of atypical epithelial cells with abundant clear cytoplasm and enlarged and centrally placed round nuclei. The tumor was exophytic with deep, penetrating proliferation. The atypical clear cells were continuous with the conventional SCC cells. Immunohistochemical analysis showed that the clear cells were positive for CK AE1/AE3 and CK5/6 and nuclear-positive for p63. In contrast, the clear cells were negative for αSMA, S100, HMB45, Melan-A, CD10, and p16. p53 immunoreactivity exhibited a wild-type expression pattern. Additionally, the clear cells were positive for periodic acid-Schiff (PAS) and negative for diastase-PAS, mucicarmine, and Alcian blue. Based on these results, the diagnosis of CCSCC was confirmed. Molecular analysis of the clear cells identified PIK3CA p.E542K (c.1624G>A) and HRAS p.G12A (c.35 G>C) somatic mutations classified as oncogenic. No pathogenic variants were identified in TP53, EWSR1, AKT1, PTEN, BRAF, KRAS, NRAS, RASA1, or MAML2.

CONCLUSIONS

We report a case of CCSCC of the oral cavity with PIK3CA and HRAS mutations. The identification of PIK3CA and/or HRAS mutations is rare in SCC; however, both mutations are important potential targets for antitumor therapy. A detailed analysis of gene mutations in CCSCC may lead to a better understanding of its biological behavior and an improved prognosis, as well as a differential diagnosis from other clear cell neoplasms.

Analysis of FctB3 crystal structure and insight into its structural stabilization and pilin linkage mechanisms

Streptococcus pyogenes harboring an FCT type 3 genomic region display pili composed of three types of pilins. In this study, the structure of the base pilin FctB from a serotype M3 strain (FctB3) was determined at 2.8 Å resolution. In accordance with the previously reported structure of FctB from a serotype T9 strain (FctB9), FctB3 was found to consist of an immunoglobulin-like domain and proline-rich tail region. Data obtained from structure comparison revealed main differences in the omega (Ω) loop structure and the proline-rich tail direction. In the Ω loop structure, a differential hydrogen bond network was observed, while the lysine residue responsible for linkage to growing pili was located at the same position in both structures, which indicated that switching of the hydrogen bond network in the Ω loop without changing the lysine position is advantageous for linkage to the backbone pilin FctA. The difference in direction of the proline-rich tail is potentially caused by a single residue located at the root of the proline-rich tail. Also, the FctB3 structure was found to be stabilized by intramolecular large hydrophobic interactions instead of an isopeptide bond. Comparisons of the FctB3 and FctA structures indicated that the FctA structure is more favorable for linkage to FctA. In addition, the heterodimer formation of FctB with Cpa or FctA was shown to be mediated by the putative chaperone SipA. Together, these findings provide an alternative FctB structure as well as insight into the interactions between pilin proteins.

Rab32 and Rab38 maintain bone homeostasis by regulating intracellular traffic in osteoclasts

Osteoclasts play a crucial role in bone homeostasis by forming resorption pits on bone surfaces, resulting in bone resorption. The osteoclast expression of Rab38 protein is highly induced during differentiation from macrophages. Here we generated mice with double knockout (DKO) of Rab38 and its paralogue, Rab32, to investigate the roles of these proteins in osteoclasts. Bone marrow-derived macrophages from Rab32/38 DKO mice differentiated normally into osteoclasts in vitro. However, DKO osteoclasts showed reduced bone resorption activity. These osteoclasts also demonstrated defective secretion of tartrate-resistant acid phosphatase and cathepsin K into culture medium. Furthermore, the plasma membrane localization of a3, an osteoclast-specific a subunit of V-ATPase, was abrogated in DKO mice, substantiating the reduced resorption activity. In vivo, Rab32- and Rab38-positive cells were attached to the bone surface. Eight-week-old DKO mice showed significantly thickened trabecular bones in micro-CT and histomorphometry analysis, as well as reduced serum levels of cross-linked C-telopeptide of type I collagen, indicating diminished bone resorption in vivo. In DKO male mice over 10 weeks of age, hyperostosis appeared at the talofibular syndesmosis, the distal junction of the tibia and fibula. Furthermore, middle-aged mice (10 to 12 months of age) exhibited kyphosis, which is not usually observed in wild-type male mice until around 24 months of age. These results indicate that Rab32 and Rab38 contribute to osteoclast function by supporting intracellular traffic, thereby maintaining normal bone homeostasis.Key words: Rab32, Rab38, osteoclast, lysosome-related organelle, secretory lysosome.

Potential Role of the Intratumoral Microbiota in Prognosis of Head and Neck Cancer

The tumor microbiome, a relatively new research field, affects tumor progression through several mechanisms. The Cancer Microbiome Atlas (TCMA) database was recently published. In the present study, we used TCMA and The Cancer Genome Atlas and examined microbiome profiling in head and neck squamous cell carcinoma (HNSCC), the role of the intratumoral microbiota in the prognosis of HNSCC patients, and differentially expressed genes in tumor cells in relation to specific bacterial infections. We investigated 18 microbes at the genus level that differed between solid normal tissue (n = 22) and primary tumors (n = 154). The tissue microbiome profiles of Actinomyces, Fusobacterium, and Rothia at the genus level differed between the solid normal tissue and primary tumors of HNSCC patients. When the prognosis of groups with rates over and under the median for each microbe at the genus level was examined, rates for Leptotrichia which were over the median correlated with significantly higher overall survival rates. We then extracted 35 differentially expressed genes between the over- and under-the-median-for-Leptotrichia groups based on the criteria of >1.5 fold and p < 0.05 in the Mann-Whitney U-test. A pathway analysis showed that these Leptotrichia-related genes were associated with the pathways of Alzheimer disease, neurodegeneration-multiple diseases, prion disease, MAPK signaling, and PI3K-Akt signaling, while protein-protein interaction analysis revealed that these genes formed a dense network. In conclusion, probiotics and specific antimicrobial therapy targeting Leptotrichia may have an impact on the prognosis of HNSCC.

Fam20C overexpression in odontoblasts regulates dentin formation and odontoblast differentiation

FAM20C phosphorylates secretory proteins at S-x-E/pS motifs, and previous studies of Fam20C-dificient mice revealed that FAM20C played essential roles in bone and tooth formation. Inactivation of FAM20C in mice led to hypophosphatemia that masks direct effect of FAM20C in these tissues, and consequently the direct role of FAM20C remains unknown. Our previous study reported that osteoblast/odontoblast-specific Fam20C transgenic (Fam20C-Tg) mice had normal serum phosphate levels and that osteoblastic FAM20C-mediated phosphorylation regulated bone formation and resorption. Here, we investigated the direct role of FAM20C in dentin using Fam20C-Tg mice. The tooth of Fam20C-Tg mice contained numerous highly phosphorylated proteins, including SIBLINGs, compared to that of wild-type mice. In Fam20C-Tg mice, coronal dentin volume decreased and mineral density unchanged at early age, while the volume unchanged and the mineral density elevated at maturity. In these mice, radicular dentin volume and mineral density decreased at all ages, and histologically, the radicular dentin had wider predentin and abnormal apical-side dentin with embedded cells and argyrophilic canaliculi. Immunohistochemical analyses revealed that abnormal apical-side dentin had bone and dentin matrix properties accompanied with osteoblast-lineage cells. Further, in Fam20C-Tg mice, DSPP content which is important for dentin formation, was reduced in dentin, especially radicular dentin, which might lead to defects mainly in radicular dentin. Renal subcapsular transplantations of tooth germ revealed that newly formed radicular dentin replicated apical abnormal dentin of Fam20C-Tg mice, corroborating that FAM20C overexpression indeed caused the abnormal dentin. Our findings indicate that odontoblastic FAM20C-mediated phosphorylation in the tooth regulates dentin formation and odontoblast differentiation.

Structural and Computational Analyses of the Unique Interactions of Opicapone in the Binding Pocket of Catechol O-Methyltransferase: A Crystallographic Study and Fragment Molecular Orbital Analyses

A third-generation inhibitor of catechol O-methyltransferase (COMT), opicapone (1), has the 3-nitrocatechol scaffold as do the second-generation inhibitors such as entacapone (2) and tolcapone (3), but only 1 can sustainably inhibit COMT activity making it suitable for a once-daily regimen. These improvements should be attributed to the optimized sidechain moiety (oxidopyridyloxadiazolyl group) of 1 substituted at the 5-position of the 3-nitrocatechol ring. We analyzed the role of the sidechain moiety by solving the crystal structures of COMT/S-adenosylmethionine (SAM)/Mg/1 and COMT/S-adenosylhomocysteine (SAH)/Mg/1 complexes. Fragment molecular orbital (FMO) calculations elucidated that the dispersion interaction between the sidechains of Leu 198 and Met 201 on the β6β7-loop and the oxidopyridine ring of 1 were unique and important in both complexes. In contrast, the catechol binding site made a remarkable difference in the sidechain conformation of Lys 144. The ε-amino group of Lys 144 was outside of the catalytic pocket and was replaced by a water molecule in the COMT/SAH/Mg/1 complex. No nitrocatechol inhibitor has ever been reported to make a complex with COMT and SAH. Thus, the conformational change of Lys 144 found in the COMT/SAH/Mg/1 complex is the first crystallographic evidence that supports the role of Lys 144 as a catalytic base to take out a proton ion from the reaction site to the outside of the enzyme. The fact that 1 generated a complex with SAH and COMT also suggests that 1 could inhibit COMT twofold, as a typical substrate mimic competitive inhibitor and as a product-inhibition enhancer.

Involvement of ribonuclease Y in pilus production by M49 Streptococcus pyogenes strain via modulation of messenger RNA level of transcriptional regulator

Streptococcus pyogenes displays a wide variety of pili, which is largely dependent on serotype. A distinct subset of S. pyogenes strains that possess the Nra transcriptional regulator demonstrates thermoregulated pilus production. Findings obtained in the present study of an Nra-positive serotype M49 strain revealed involvement of conserved virulence factor A (CvfA), also referred to as ribonuclease Y (RNase Y), in virulence factor expression and pilus production, while a cvfA deletion strain showed reduced pilus production and adherence to human keratinocytes as compared with wild-type and revertant strains. Furthermore, transcript levels of pilus subunits and srtC2 genes were decreased by cvfA deletion, which was remarkable at 25°C. Likewise, both messenger RNA (mRNA) and protein levels of Nra were remarkably decreased by cvfA deletion. Whether the expression of other pilus-related regulators, including fasX and CovR, was subject to thermoregulation was also examined. While the mRNA level of fasX, which inhibits cpa and fctA translation, was decreased by cvfA deletion at both 37°C and 25°C, CovR mRNA and protein levels, as well as its phosphorylation level were not significantly changed, suggesting that neither fasX nor CovR is necessarily involved in thermosensitive pilus production. Phenotypic analysis of the mutant strains revealed that culture temperature and cvfA deletion had varied effects on streptolysin S and SpeB activities. Furthermore, bactericidal assay data showed that cvfA deletion decreased the rate of survival in human blood. Together, the present findings indicate that CvfA is involved in regulation of pilus production and virulence-related phenotypes of the serotype M49 strain of S. pyogenes.

Sublingual Dermoid Cyst in Young Child

A dermoid cyst is a benign congenital lesion of ectodermal origin that can arise in any region of the body, though occurrence is rare. A young girl aged 2 years 4 months was referred to our hospital because of a painless mass in the floor of the mouth. Intraoral examination findings revealed a painless movable elastic soft mass on the floor of the mouth measuring approximately 15 mm in diameter. Magnetic resonance imaging indicated a cystic lesion, with low signal intensity shown in T1-weighted and extremely high signal intensity in T2-weighted images. These clinical findings indicated the presence of a dermoid cyst and removal was planned. Under general anesthesia with nasal intubation, surgical removal was performed through an incision on the floor of the mouth. Blunt dissection exposed the integrity of the cyst capsule, which was weakly attached to adjacent tissue. The excised mass was 19 mm × 14 mm × 11 mm in size. Histological examination findings confirmed a diagnosis of dermoid cyst. The operation was successfully completed without any complications and the postoperative course was good. It is important to properly evaluate cysts in children and provide proper treatment with appropriate timing.

Identification of the Acidification Mechanism of the Optimal pH for RNase He1

Ribonuclease (RNase) He1 is a small ribonuclease belonging to the RNase T1 family. Most of the RNase T1 family members are active at neutral pH, except for RNase Ms, U2, and He1, which function at an acidic pH. We crystallized and analyzed the structure of RNase He1 and elucidated how the acidic amino residues of the α1β3- (He1:26-33) and β67-loops (He1:87-95) affect their optimal pH. In He1, Ms, and U2, the hydrogen bonding network formed by the acidic amino acids in the β67-loop suggested that the differences in the acidification mechanism of the optimum pH specified the function of these RNases. We found that the amino acid sequence of the β67-loop was not conserved and contributed to acidification of the optimum pH in different ways. Mutations in the acidic residues in He1 promoted anti-tumor growth activity, which clarified the role of these acidic amino residues in the binding pocket. These findings will enable the identification of additional targets for modifying pH-mediated enzymatic activities.

Effective oral function improvement by restoration-driven implant treatment after mandibular resection with a scapular flap: a case report

BACKGROUND

The extensive loss of teeth and surrounding tissues due to mandibulectomy for an oral tumor not only impacts negatively on appearance, but also often causes various functional disorders, decreasing quality of life (QOL). In the present case, reconstruction with a scapular flap was carried out along with segmental mandibulectomy, aiming for functional restoration through restoration-driven implant treatment. A good outcome was obtained, with improvement of masticatory function and QOL following the prosthetic treatment.

CASE PRESENTATION

The patient was a 37-year-old woman diagnosed with ossifying fibroma in the left side of the mandible. Segmental mandibulectomy and reconstruction with a scapular flap were carried out. Implant diagnostic simulation was performed, and based on the result, secondary reconstruction using a particulate cancellous bone and marrow graft was carried out by an oral surgeon. After wound healing was complete, implant placement was performed twice, and the final prosthodontic treatment was completed. Masticatory performance and maximum bite force, which are indices of masticatory function, were improved from before to after prosthetic treatment. In addition, oral health-related QOL was improved from before to after prosthetic treatment.

CONCLUSION

In the present case, restoration-driven implant treatment was performed in a patient following segmental mandibulectomy for a mandibular tumor, with a good outcome. Planning the treatment measures with a focus on the final prosthetic vision can lead to improvement of oral function in patients with extensive mandibular defects.

Determination of Significant Prognostic Factors for Maxillary Gingival Squamous Cell Carcinoma in 90 Cases

Maxillary gingival squamous cell carcinoma (MGSCC) occurs rather infrequently, compared to tongue and mandibular gingival carcinomas, among the cancers of the oral cavity. Therefore, significant numbers of MGSCC cases have not been statistically analysed. The aim of this study is to clarify the prognostic factors for MGSCC. We performed the statistical analysis of 90 MGSCC cases primarily treated in our department from 1999 to 2014. The patients (male: 36, female: 54) were aged between 38 and 93 years, and the mean age was 68.7 years. The number of patients in each tumour stage according to the TNM classification was as follows: T1: 15 cases, T2: 32 cases, T3: 13 cases, and T4: 30 cases. Forty-two patients were treated only by surgery, 5 only by radiotherapy, 3 by preoperative radiotherapy and surgery, and 40 patients were treated by combination therapy with preoperative chemoradiotherapy and surgery. Neck dissections were performed in 40 cases including 29 cases (11 primary and 18 secondary cases) of histopathologically diagnosed lymph node metastases. Extranodal extension was found in 74.3% cases with metastatic lymph nodes. The 5-year overall survival rate was 81.9%. In univariate analysis, the site of occurrence, stage of tumour, lymph node metastasis, and treatment contributed to the 5-year survival rate. Multivariate analysis demonstrated that the site of occurrence (posterior region) was an independent prognostic factor. Seventeen deaths occurred due to the primary disease, while three deaths were caused by other diseases. The posterior region cancers, according to the classification based on site of occurrence, were independent predictors of poor 5-year overall survival rate.

Pleomorphic Adenoma of the Salivary Glands and Epithelial–Mesenchymal Transition

Pleomorphic adenoma (PA) is a localized tumor that presents pleomorphic or mixed characteristics of epithelial origin and is interwoven with mucoid tissue, myxoid tissue, and chondroid masses. The literature reported that PA most often occurs in adults aged 30–60 years and is a female predilection; the exact etiology remains unclear. Epithelial–mesenchymal transition (EMT) is the transdifferentiation of stationary epithelial cells primarily activated by a core set of transcription factors (EMT-TFs) involved in DNA repair and offers advantages under various stress conditions. Data have suggested that EMTs represent the basic principle of tissue heterogeneity in PAs, demonstrating the potential of adult epithelial cells to transdifferentiate into mesenchymal cells. It has also been reported that multiple TFs, such as TWIST and SLUG, are involved in EMT in PA and that SLUG could play an essential role in the transition from myoepithelial to mesenchymal cells. Given this background, this review aims to summarize and clarify the involvement of EMT in the development of PA, chondrocyte differentiation, and malignant transformation to contribute to the fundamental elucidation of the mechanisms underlying EMT.

Pneumococcal BgaA Promotes Host Organ Bleeding and Coagulation in a Mouse Sepsis Model

Streptococcus pneumoniae is a major cause of invasive diseases such as pneumonia, meningitis, and sepsis, with high associated mortality. Our previous molecular evolutionary analysis revealed that the S. pneumoniae gene bgaA, encoding the enzyme β-galactosidase (BgaA), had a high proportion of codons under negative selection among the examined pneumococcal genes and that deletion of bgaA significantly reduced host mortality in a mouse intravenous infection assay. BgaA is a multifunctional protein that plays a role in cleaving terminal galactose in N-linked glycans, resistance to human neutrophil-mediated opsonophagocytic killing, and bacterial adherence to human epithelial cells. In this study, we performed in vitro and in vivo assays to evaluate the precise role of bgaA as a virulence factor in sepsis. Our in vitro assays showed that the deletion of bgaA significantly reduced the bacterial association with human lung epithelial and vascular endothelial cells. The deletion of bgaA also reduced pneumococcal survival in human blood by promoting neutrophil-mediated killing, but did not affect pneumococcal survival in mouse blood. In a mouse sepsis model, mice infected with an S. pneumoniae bgaA-deleted mutant strain exhibited upregulated host innate immunity pathways, suppressed tissue damage, and blood coagulation compared with mice infected with the wild-type strain. These results suggest that BgaA functions as a multifunctional virulence factor whereby it induces host tissue damage and blood coagulation. Taken together, our results suggest that BgaA could be an attractive target for drug design and vaccine development to control pneumococcal infection.

Tumor-infiltrating ICOS+ Effector Regulatory T-Cells in Oral Squamous Cell Carcinoma as a Promising Biomarker for Prognosis and 'Hot' Tumor

BACKGROUND

Tumor immunity in the tumor microenvironment is activated in patients with feasible clinical responses to immune checkpoint inhibitors. The immunological profile of tumor-infiltrating lymphocytes (TILs) obtained from patients with oral squamous cell carcinoma (OSCC) was examined in relation to their prognosis.

MATERIALS AND METHODS

Surface antigens, including immune checkpoint molecules, on TILs from 31 patients with primary OSCC were analyzed by flow cytometry. The activation status of TILs was examined through a heatmap analysis and unsupervised clustering classified patients into groups with activated or inactivated TILs. A supervised machine-learning algorithm for single-cell analyses in relation to prognosis was run using the Cluster Identification, Characterization, and Regression (CITRUS) program.

RESULTS

None of surface antigens were related to prognosis. The CITRUS program revealed a relationship between CD45RA^-CD4⁺ CD25^high inducible T-cell co-stimulator (ICOS)⁺ TILs and recurrence, and also identified a similar fraction significantly specific to the group with activated TILs. The disease-free survival rate for patients with ≥95% ICOS⁺ TILs was significantly lower than that for those with <95% ICOS⁺ TILs. Furthermore, a review of clinicopathological factors related to prognosis identified the percentage of ICOS⁺ TILs to be an independent prognostic factor for patients with OSCC.

CONCLUSION

CD25^highICOS⁺ regulatory T-cells in TILs have potential as a biomarker for predicting recurrence after surgical treatment and clinical responses to immune checkpoint inhibitors in patients with OSCC.

Motor representation of rhythmic jaw movements in the amygdala of guinea pigs

OBJECTIVE

The areas of the amygdala contributing to rhythmic jaw movements and the movement patterns induced remain unknown. Therefore, the present study investigated the areas of the amygdala contributing to rhythmic jaw movements using repetitive electrical microstimulation techniques.

DESIGN

Experiments were performed on head-restrained guinea pigs under ketamine-xylazine anesthesia. EMG activities in the masseter and digastric muscles and jaw movements were recorded. Short- and long-train electrical microstimulations of the amygdala were performed and the patterns of jaw movements induced were analyzed quantitatively.

RESULT

The short-train stimulation induced short-latency EMG responses in the masseter and/or digastric muscles. The stimulation sites inducing short-latency EMG responses were distributed within the ventral part of the amygdala, which covered the medial, basal, and cortical nuclei. The long-train stimulation induced tonic jaw opening and two types of rhythmic jaw movements: those with or without lateral jaw shifts, which were characterized by a larger jaw gape and ipsilateral jaw excursion, respectively. Rhythmic jaw movements with lateral jaw shifts were characterized by overlapping masseter and digastric EMG activities. However, rhythmic patterns did not differ between the two types of rhythmic jaw movements. The stimulation sites that induced rhythmic jaw movements were more localized to the cortical nucleus.

CONCLUSIONS

The present results suggest that the ventral part of the amygdala is involved in the induction of rhythmic jaw movements in guinea pigs. The putative roles of the limbic system in the genesis of functional (e.g., chewing) and non-functional (e.g., bruxism) rhythmic oromotor movements warrant further study.

The HIF-1α pathway plays a critical role in salivary gland development in ex vivo organ cultures

The transcription factor, hypoxia‐inducible factor‐1α (HIF‐1α), has previously been shown to upregulate the expression of hypoxia‐related genes, including erythropoietin (EPO). However, the role of hypoxia‐inducible factor‐1α in morphogenesis during salivary gland development is unclear. We investigated the function of HIF‐1α in submandibular gland (SMG) organ cultures obtained from embryonic day 13.5 embryos from ICR female mice. Expression of HIF‐1α, glucose transporter 1, and vascular endothelial growth factor was induced under hypoxia (5% O₂). We further showed that BAY 87‐2243‐mediated inhibition of HIF‐1α suppressed salivary gland development. Under severe hypoxia (1% O₂), HIF‐1α did not promote salivary gland development; this was due to suppression of cell proliferation and inhibition of the cell cycle and not because of autophagy and apoptosis. Additionally, using the inhibitor U0126, we verified that the ERK1/2 pathway is upstream of HIF‐1α. Overall, we found that the HIF‐1α signaling pathway plays a critical role in salivary gland development in ex vivo SMG organ cultures.

Changes in cortical, cardiac, and respiratory activities in relation to spontaneous rhythmic jaw movements in ketamine-anesthetized guinea pigs

It has been reported that rhythmic jaw movements (RJMs) spontaneously occur in ketamine-anesthetized animals. The present study investigated the physiological processes that occur during the cortical, cardiac, and respiratory events which contribute to the genesis of RJMs in animals after supplemental ketamine injections. Fourteen guinea pigs were prepared to allow electroencephalographic, electrocardiographic, and electromyographic activities to be recorded from the digastric muscle, measurement of jaw movements, and nasal expiratory airflow under ketamine-xylazine anesthesia. Rhythmic jaw movements spontaneously occurred with rhythmic digastric muscle contractions, 23-29 minutes after injection of supplemental ketamine (12.5 and 25.0 mg kg^-1 , intravenously). The cycle length of RJMs did not differ significantly between the two doses of ketamine (mean±SD: 12.5 mg kg^-1 , 326.5 ± 60.0 ms; 25 mg kg^-1 , 278.5 ± 45.1 ms). Following injection of ketamine, digastric muscle activity, heart and respiratory rates, and cortical beta power significantly decreased, while cortical delta and theta power significantly increased. These changes were significantly larger in animals given 25.0 mg kg^-1 of ketamine than in those given 12.5 mg kg^-1 . With the onset of RJMs, the levels of these variables returned to pre-injection levels, regardless of the dose of ketamine administered. These results suggest that, following supplemental ketamine injections, spontaneous RJMs occur during a specific period when the pharmacological effects of ketamine wear off, and that these RJMs are characterized by stereotypical changes in cardiac, respiratory, and cortical activities.

Clear Cell Carcinoma in the Oral Cavity with Three Novel Types of EWSR1-ATF1 Translocation: A Case Report

Clear cell carcinoma (CCC) is a rare epithelial malignant tumor of the salivary glands. It is characterized by tumor cells with clear cytoplasm, hyalinized stroma, and most importantly the fusion genes EWSR1-ATF1, EWSR1-CREM, and EWSR1-PLAG1. Break-apart FISH has been performed for multiple CCC cases, but direct sequencing analysis has been performed in relatively few. Herein, we report an interesting case of CCC harboring three EWSR1-ATF1 translocations: EWSR1 exon 8-ATF1 exon 4, EWSR1 exon 7-ATF1 exon 4, and EWSR1 exon 7-ATF1 exon 5. This case indicates the possibility of independent EWSR1-ATF1 gene translocations, and could provide insight into CCC tumorgenesis.

Predictive scoring model for inferior alveolar nerve injury after lower third molar removal based on features of cone-beam computed tomography image

INTRODUCTION

This study aimed to construct a predictive scoring system for inferior alveolar nerve injury (IANI) following lower third molar (LM3) surgery based on cone-beam computed tomography (CBCT) images.

MATERIAL AND METHODS

Of the 1573 patients who underwent LM3 removal following the CBCT, 39 with IANI and 457 randomly selected patients without IANI were enrolled. We collected information regarding the demographic characteristics of the patients, surgical situations, and inferior alveolar canal (IAC)-related CBCT factors. The association with IANI-risk was evaluated with a backward stepwise logistic regression model as per the Akaike information criterion. Scoring models' abilities of discrimination (area under the curve) and calibration (Hosmer-Lemeshow test and calibration plots) were assessed, followed by evaluation of the clinical usefulness using decision curve analysis.

RESULTS

As per the multivariate analysis, the coronal positioned IAC on the enlarged root (odds ratio [OR], 3.78; P = 0.001), the length of perforated IAC (>3.4 mm) (OR, 3.05; P = 0.012), lingual/inter-radicular position of the IAC (OR, 3.96; P = 0.001), multiple roots closed to the perforated IAC (OR, 2.78; P = 0.025), and age >30 y (OR, 2.31; P = 0.076) were identified in the extended scoring model ranging from 0 to 12. This model was compared with our previously constructed baseline model that involved the latter three variables mentioned above, resulting in superior performance than that of the baseline model.

CONCLUSION

The extended model would be a useful tool for reliable determination of the preoperative probability of IANI.

General rules for clinical and pathological studies on oral cancer (2nd edition): a synopsis

For doctors and other medical staff treating oral cancer, it is necessary to standardize the basic concepts and rules for oral cancer to achieve progress in its treatment, research, and diagnosis. Oral cancer is an integral part of head and neck cancer and is treated in accordance with the general rules for head and neck cancer. However, detailed rules based on the specific characteristics of oral cancer are essential. The objective of this article was to contribute to the development of the diagnosis, treatment, and research of oral cancer, based on the correct and useful medical information of clinical, surgical, pathological, and imaging findings accumulated from individual patients at various institutions. Our general rules were revised as the UICC was revised for the 8th edition and were published as the Japanese second edition in 2019. In this paper, the English edition of the "Rules" section is primarily presented.

Case Report: Hidden Oral Squamous Cell Carcinoma in Oral Somatic Symptom Disorder

Background: Burning mouth syndrome (BMS) is a common condition of predominant oral pain without evident cause, that maxillofacial surgeons and otolaryngologists often refer to psychiatrists as somatic symptom disorder. In very rare cases, its typical burning symptom mimics those of other diseases in which serious fatal comorbidities may be missed. We encountered three rare cases of oral squamous cell carcinoma (OSCC) with the first symptom of burning tongue. Case Presentation: Case 1: A 68-year-old woman had burning pain on the left lingual margin for 8 years. Antidepressant treatment was not efficacious. Cytology and biopsy revealed OSCC. Case 2: A 70-year-old man had burning sensation and paralysis of the tongue for 6 months. Magnetic resonance imaging (MRI) revealed a 37 × 23-mm mass under the floor of the mouth and enlargement of lymph nodes on both sides. Case 3: A 90-year-old man had burning sensation of the tongue for 1 year. MRI revealed a 12 × 12-mm mass on the mandible with bone absorption. Conclusion: This case series suggests that psychiatrists must always be careful in regarding BMS as somatic symptom disorder and be cautious of the possibility of OSCC, especially in elderly patients.

Treatment outcomes of adjunctive teriparatide therapy for medication-related osteonecrosis of the jaw (MRONJ): A multicenter retrospective analysis in Japan

BACKGROUND

Therapeutic strategies for patients with medication-related osteonecrosis of the jaw (MRONJ) remain controversial. The aim of the present study was to clarify the effectiveness and safety of teriparatide therapy in Japanese MRONJ patients based on a large number of case series with a multicenter retrospective analysis.

PATIENTS AND METHODS

Between January 2012 and December 2016, 29 patients who were diagnosed with MRONJ at 10 hospitals were treated with teriparatide. The medical records of these patients were retrospectively reviewed to assess the efficacy and safety of teriparatide therapy for MRONJ patients.

RESULTS

Adverse events occurred in 17.2% of patients (5/29). One patient developed severe arthralgia and discontinued teriparatide therapy after 12 days, while others continued the treatment. Among 29 patients, the median period of administration of teriparatide was 14.0 months (range, 0.3-26 months), and treatment outcomes were evaluated as effective in 75.9% of patients with complete resolution in 65.5%. Among patients treated with oral bisphosphonates (BPs), 83.3% were effectively treated with teriparatide and 40% with intravenous BPs. The oral administration of BPs was associated with successful treatment outcomes with teriparatide (p = 0.062).

CONCLUSIONS

Teriparatide therapy has potential as an effective treatment option for MRONJ.

Role of BgaA as a Pneumococcal Virulence Factor Elucidated by Molecular Evolutionary Analysis

Streptococcus pneumoniae is a major cause of pneumonia, sepsis, and meningitis. Previously, we identified a novel virulence factor by investigating evolutionary selective pressure exerted on pneumococcal choline-binding cell surface proteins. Herein, we focus on another pneumococcal cell surface protein. Cell wall-anchoring proteins containing the LPXTG motif are conserved in Gram-positive bacteria. Our evolutionary analysis showed that among the examined genes, nanA and bgaA had high proportions of codon that were under significant negative selection. Both nanA and bgaA encode a multi-functional glycosidase that aids nutrient acquisition in a glucose-poor environment, pneumococcal adherence to host cells, and evasion from host immunity. However, several studies have shown that the role of BgaA is limited in a mouse pneumonia model, and it remains unclear if BgaA affects pneumococcal pathogenesis in a mouse sepsis model. To evaluate the distribution and pathogenicity of bgaA, we performed phylogenetic analysis and intravenous infection assay. In both Bayesian and maximum likelihood phylogenetic trees, the genetic distances between pneumococcal bgaA was small, and the cluster of pneumococcal bgaA did not contain other bacterial orthologs except for a Streptococcus gwangjuense gene. Evolutionary analysis and BgaA structure indicated BgaA active site was not allowed to change. The mouse infection assay showed that the deletion of bgaA significantly reduced host mortality. These results indicated that both nanA and bgaA encode evolutionally conserved pneumococcal virulence factors and that molecular evolutionary analysis could be a useful alternative strategy for identification of virulence factors.

A novel multiple-catheter implantation method for advanced head and neck cancer

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Background: We previously developed a super-selective intra-arterial chemotherapy (iaCT) approach for head and neck cancer (HNC), by which, an intra-arterial catheter is retrogradely inserted via either the superficial temporal artery (STA) or occipital artery (OA) and connected to a subcutaneous reservoir. As a result, since this approach overcomes the need for frequent fluoroscopy sessions, the infusion frequency can be increased and the therapeutic effectiveness improved. However, since the anticancer effect is limited to the region supplied by the selected blood vessel, it is often difficult to control an advanced HNC by single-catheter iaCT. Subsequently, a novel multiple-catheter implantation method (MCIM) for super-selective iaCT has been developed using, both, the STA and OA. Methods: A total of 21 patients with stage III or IV HNC were enrolled in this study and treated via MCIM for iaCT between 2009 and 2017. The catheters were super-selectively placed in the tumor-feeding arteries after having entered the STA or OA. The first catheter was introduced into one of the target branches. Next, a second catheter was introduced into another target branch. If a third catheter was required, the procedure was repeated. The extra-arterial portions of the catheters were subcutaneously connected to an implanted juxta-mastoidal infusion reservoir. Results: The response rate was 100%; particularly, 20 cases of complete response and 1 of partial response were confirmed. Although the partial responder underwent salvage surgery and two complete responders ultimately died (due to either delayed recurrence or brain metastases), the other 18 patients have been living cancer-free for 2-9 years. Conclusions: The MCIM method allows to expand the infusion region while maintaining the main advantages of super-selective iaCT. As a consequence, due to the lack of need for patient confinement in the catheter room and for frequent fluoroscopy sessions, patients’ mental and physical distress, medical expenses, and treatment time are all ultimately reduced.

Ascending projection of jaw-closing muscle-proprioception to the intralaminar thalamic nuclei in rats

An invasive intralaminar thalamic stimulation and a non-invasive application of oral splint are both effective in treating tic symptoms of patients with Tourette syndrome (TS). Therefore, these two treatments may exert some influence on the same brain region in TS patients. We thus hypothesized that the proprioceptive input arising from the muscle spindles of jaw-closing muscles (JCMSs), known to be increased by the application of oral splint, is transmitted to the intralaminar thalamic nuclei. To test this issue, we morphologically and electrophysiologically examined the thalamic projections of proprioceptive input from the JCMSs to the intralaminar thalamic nuclei of rats. We first injected an anterograde tracer, biotinylated dextranamine, into the electrophysiologically identified supratrigeminal nucleus, which is known to receive proprioceptive inputs from the JCMSs via the trigeminal mesencephalic neurons. A moderate number of biotinylated dextranamine-labeled axon terminals were bilaterally distributed in the oval paracentral nucleus (OPC) of the intralaminar thalamic nuclei. We also detected electrophysiological responses to the electrical stimulation of bilateral masseter nerves and to sustained jaw-opening in the OPC. After injection of retrograde tracer (cholera toxin B subunit or Fluorogold) into the OPC, neuronal cell bodies were retrogradely labeled in the rostrodorsal portion of the bilateral supratrigeminal nucleus. Here, we show that proprioceptive inputs from the JCMSs are conveyed to the OPC in the intralaminar nuclei via the supratrigeminal nucleus. This study can help to understand previously unrecognized pathways of proprioception ascending inputs from the brainstem to the thalamus, which may contribute to treatments of TS patients.

An Avulsed Tooth Detected Prior to Insertion of a Laryngeal Mask Airway

This case report describes the importance of inspecting the hypopharynx via direct laryngoscopy prior to laryngeal mask airway (LMA) insertion during induction of general anesthesia for dental patients with special needs. A 51-year-old man with cerebral palsy underwent induction of general anesthesia for dental extractions and subsequently was noted to be missing a tooth. Prompt inspection of the airway via direct laryngoscopy revealed the tooth resting within the pharynx, which was subsequently retrieved, prior to insertion of the LMA. Visual inspection of the oropharynx and hypopharynx by laryngoscopy prior to LMA insertion can be useful in preventing accidental aspiration and ingestion of foreign bodies, particularly with certain high-risk patients. Use of laryngoscopy should also be considered if an object is lost or possibly impinging upon the airway.

Glucose metabolism changes during the development and progression of oral tongue squamous cell carcinomas

Previous studies have revealed several genes involved in the carcinogenesis of oral cancer. However, the detailed mechanisms underlying this process are poorly understood. Previously, we established a database cataloging the transcriptional progression profile of oral carcinogenesis and identified several candidate genes with continuously increasing or decreasing expression, which specifically promote the transition of oral premalignant lesions to invasive carcinomas. In this study, using our microarray database, we attempted to determine significant genes that may contribute to metabolic alterations during oral carcinogenesis. After performing a literature survey, we focused on 15 candidate genes associated with glucose metabolism changes, particularly the tri-carboxylic acid cycle, and investigated the mRNA-expression status of these genes with our database. Only the solute carrier family 2 member 1 gene (also known as GLUT1), showed significantly increased mRNA expression during oral tumorigenesis. Immunohistochemical analysis confirmed that GLUT1 protein expression significantly increased during oral carcinogenesis. In addition, tumors with high expression of this protein significantly correlated with nodal status (P=0.002). Kaplan-Meier survival curves clearly demonstrated the adverse impact of high GLUT1 protein expression on disease-free survival (P=0.004). GLUT1 mRNA and protein expression increased in the order of normal mucosal tissues, epithelial dysplastic lesions and invasive carcinomas. Therefore, metabolic alterations, especially in glucose metabolism, occurred at the very early stage of development of oral malignancies. In addition, GLUT1 played a significant role in oral cancer, acquiring a malignant phenotype.

High-dose, short-duration, intra-arterial cisplatin therapy for oral cancer

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Background: We developed a superselective intra-arterial chemotherapy (iaCT) approach for oral cancer wherein an intra-arterial catheter is retrogradely inserted via the superficial temporal artery (STA) and/or occipital artery (OA). In most iaCT cases, high-dose anticancer agents are administrated via the intra-arterial catheter weekly or biweekly with daily irradiation. This approach remarkably improves curative efficiency, but some adverse events, e.g., severe mucositis, dysphagia, dysgeusia, dry mouth, and radiation osteonecrosis, mainly because of irradiation, decrease the quality of life. Methods: Thirty-two patients with stage II, III, or IV oral squamous cell carcinoma were treated using this new iaCT approach. The catheter was superselectively placed in the tumor-feeding arteries by cut-down of STA or OA. The catheter was completely placed under the skin and was connected to an infusion reservoir that was subcutaneously implanted around the mastoid process via the subcutaneous tunnel, ensuring little possibility of catheter-related issues such as infection and displacement of catheter. Anticancer agents (30 mg/m2of cisplatin with/without 10 mg/m2of docetaxel) were intra-arterially administered via the reservoir twice a week for 3 weeks, 180 mg/m2/6 times in total, without irradiation. The treatment effect was assessed using computed tomography, positron emission tomography, and biopsy. Results: The response rate of this approach was 100%, with 31 and 1 case having complete response (CR) and partial response (PR), respectively. Five patients with delayed regional lymph node metastasis or PR underwent salvage surgery; 28 patients (87.5%) had disease-free survival, while 2 (6.2%) died due to local recurrence and 2 due to distant metastasis. All patients developed CTCAE v4.0 Grade 2 oral mucositis in the flow area of the intended artery, most of which disappeared in half a year. No dry mouth, dysgeusia, and eating disorder were observed because the patients did not receive radiotherapy. No systemic adverse events such as hematologic toxicity and renal and/or hepatic injuries occurred. Conclusions: This method improved the adverse event of iaCT with radiotherapy, and the main advantage of superselective iaCT was not lost.

Potential involvement of Helicobacter pylori from oral specimens in overweight body-mass index

The bacterium Helicobacter pylori was originally classified in the Campylobacter genus, which contains major periodontopathic bacterial species, and H. pylori DNA has been found in the oral cavity. Although many studies show an association between the presence of periodontal bacteria and an overweight body-mass index (BMI; >25 kg/m²), the relationship between body weight and the presence of H. pylori in the oral cavity has not been demonstrated. Herein, we analysed the relationship between H. pylori in the oral cavity and systemic conditions, including the overweight BMI. Saliva specimens and extracted teeth were obtained from 87 subjects; the distribution of H. pylori among these specimens was analysed with the polymerase chain reaction. Subjects with an overweight BMI exhibited significantly higher detection rates of H. pylori in saliva, compared with non-overweight subjects (BMI <25 kg/m²) (P < 0.05). A clinical history of digestive diseases was not associated with the presence of H. pylori in overweight subjects, whereas subjects with both severe dental caries and an overweight BMI showed a higher detection rate of H. pylori in saliva specimens, compared with other groups. These results suggest that the detection of H. pylori in the oral cavity could be associated with the overweight BMI, which was predominant among subjects with severe dental caries.

Surgical approaches for condylar fractures related to facial nerve injury: deep versus superficial dissection

The aim of this study was to investigate the probability of facial nerve injury (FNI) in the treatment of condylar neck and subcondylar fractures (CN/SCFs) with percutaneous approaches and to identify factors predicting FNI. The data of 80 patients with 87 CN/SCFs were evaluated retrospectively. The primary outcome was FNI occurrence. The predictor variables were age, sex, aetiology, alcohol consumption, fracture site and pattern (dislocation or not), concomitant fractures, time interval to surgery, surgeon experience, plate type, and the dual classification of percutaneous approaches. The approaches were classified based on whether subcutaneous dissection traversed the marginal mandibular branch (MMB) deeply (deep group: submandibular and retroparotid approaches) or superficially (superficial group: transparotid, transmasseteric anteroparotid (TMAP), and high cervical-TMAP approaches). Twenty-two patients (27.5%) suffered FNI, of whom two in the deep group had permanent paralysis of the MMB. In the multivariate logistic regression model, deeply traversing surgery approaches (odds ratio 12.4, P=0.025) and the presence of a dislocated fracture (odds ratio 6.66, P=0.012) were associated with an increased risk of FNI. These results suggest that percutaneous approaches in the superficial group should be recommended for the treatment of CN/SCFs to reduce the risk of FNI.

Small size of metastatic lymph nodes with extracapsular spread greatly impacts treatment outcomes in oral squamous cell carcinoma patients

Extracapsular spread (ECS) of metastatic lymph nodes from oral carcinoma is the most significant prognostic predictor of a poor treatment outcome. However, only a few reports on prognostic factors in ECS-positive cases have been investigated. To address this problem, a detailed examination of ECS pathology was conducted to determine the prognostic factors of oral squamous cell carcinoma (OSCC) with ECS of metastatic lymph nodes. This study involved 63 OSCC patients with at least one pathologically metastatic node with ECS. Among the 229 metastatic lymph nodes, 149 exhibited ECS. Univariate analysis revealed that a poor outcome and recurrence were significantly associated with the number of ECS-positive nodes, density of ECS, and the minor axis of the smallest ECS-positive node. However, multivariate analysis identified only small size of ECS-positive nodes as a significant and independent factor predicting recurrence and a poor outcome. Thus, small size of ECS-positive nodes is the most important prognostic indicator for OSCC with ECS in metastatic lymph nodes. The classification of ECS status using the minor axis of ECS-positive nodes may be useful for further prediction of a poorer prognosis in OSCC cases. Standardization of ECS diagnosis and multicenter prospective studies will be required to confirm and refine these findings.

Potential factors influencing the development of oral tongue squamous cell carcinoma in young mature patients: Lingual position of the mandibular second molar and narrow tongue space

The lingual position of the mandibular second molar and narrow tongue space are associated with oral tongue squamous cell carcinoma (OTSCC) development in young mature patients. The present study aimed to assess the role of the mandibular second molar position and tongue space in young mature patients with OTSCC. The medical records of 21 patients with OTSCC aged <50 years, who had an intact mandibular second molar and had undergone computed tomography (CT) imaging between April 2009 and December 2015 at the Section of Maxillofacial Surgery in Tokyo Medical and Dental University, were retrospectively examined. As controls, 21 sex-matched patients of a similar age to the patients in the OTSCC group, and with a height and weight within 5% of those of the OTSCC group, were collected. The location of the mandibular second molar on the affected side and area of the tongue space were determined using coronal and axial CT images. Mann-Whitney U test analysis revealed that the location of the mandibular second molar and the area of the tongue space differed significantly between young mature patients with OTSCC and the controls. The present study thus revealed that the lingual position of the mandibular second molar and the narrow tongue space may be potential factors influencing OTSCC development in young maturity.

Clinical Study of 597 Oral Squamous Cell Carcinomas in Our Department - Especially about 318 Tongue Carcinoma

This clinico-statistical study includes 597 cases of oral squamous cell carcinoma treated at the Maxillofacial Surgery Section of Tokyo Medical and Dental University between January 2002 and December 2011. There were 373 male and 224 female patients (male to female ratio, 1.7 : 1), and the median age was 67 years. The tongue (53.3%) was the most commonly affected site. The 5-year disease-specific survival rate was 84.8%. Survival rates by clinical stage were as follows : Stage 1, 92.1% (n=195).; Stage , 86.0% (n = 221) ; Stage III, 77.7% (n=65) ; and Stage IV, 73.8% (n =116). Survival rates by primary site were as follows: tongue, 85.4% (n=318) ; lower gingiva, 82.8% (n =114) upper gingiva, 83.7% (n=59) ; buccal mucosa, 89.1% (n 54) ; oral floor, 81.4% (n=49) ; and hard palate, 100% (n=3). According to clinical growth patterns of Stage I / I tongue cancer cases, the 5-year disease-specific survival rate was significantly higher for patients with the exophytic/superficial type (97.3%, n =173) than for those with the endophytic type (77.5%, n=145). Among Stage I/II tongue cancer cases, the corresponding survival rate was significantly higher for patients who had not previously undergone invasive treatments (n=201), such as tooth extraction, compared to those who had previously done so (n=54) (92.7% and 79.7%, respectively). In addition, the incidence of secondary cervical lymph node metastasis was significantly higher in patients who had previously undergone invasive treatments.

Primary intraosseous squamous cell carcinoma derived from a maxillary cyst: A case report and literature review

Primary intraosseous squamous cell carcinoma (PIOSCC) is a rare malignant central jaw tumor derived from odontogenic epithelial remnants. PIOSCC predominantly affects the mandible, although both jawbones may be involved. This case report describes a PIOSCC type 2 of the maxilla in a 37-year-old man, treated by partial maxillectomy. Histopathologically, the tumor was diagnosed as PIOSCC derived from an odontogenic cyst. Postoperatively, the patient has been followed up for 53 months, with no recurrence of the disease. We herein describe the clinical details, treatment results and histopathological characteristics of a rare case of PIOSCC derived from a maxillary odontogenic cyst with reference to the relevant literature.