MRI susceptibility artefacts caused by orthodontic wire.

OBJECTIVES: To evaluate magnetic susceptibility artefacts produced by orthodontic wires on MRI and the influence of wire properties and MRI image sequences on the magnitude of the artefact. METHODS: Arch form orthodontic wires [four stainless steels (SS), one cobalt chromium (CC) alloy, 13 titanium (Ti) alloys] were embedded in a polyester phantom, and scanned using a 1.5-T superconducting magnet scanner with an eight-channel phased-array coil. All wires were scanned with T1-weighted spin echo (SE) and gradient echo (GRE) sequences according to the American Society for Testing and Materials (ASTM) F2119-07 standard. The phantom also scanned other eight sequences. Artefacts were measured using the ASTM F2119-07 definition and OsiriX software. Artefact volume was analysed according to metal composition, wire length, number of wires, wire thickness, and imaging sequence as factors. RESULTS: With SE/GRE, black/white artefacts volumes from all SS wires were significantly larger than those produced by CC and Ti wires (P < .01). With the GRE, the black artefacts volume was the highest with the SS wires. With the SE, the black artefacts volume was small, whereas white artefacts were noticeable. The cranio-caudal extent of the artefacts was significantly longer with SS wires (P < .01). Although a direct relationship of wire length, number of wires, and wire thickness with artefact volume was noted, these factors did not influence artefact extension in the cranio-caudal direction. CONCLUSIONS: Ferromagnetic/paramagnetic orthodontic wires create artefacts due to local alteration of magnetic field homogeneity. The SS-type wires produced the largest artefacts followed by CC and Ti.

Involvement of an FTO gene polymorphism in the temporomandibular joint osteoarthritis.

OBJECTIVES: The FTO gene has been reported as an obesity-associated gene and is also considered a risk gene for osteoarthritis (OA). However, its exact function is unclear, and there is conflicting evidence on the involvement of FTO polymorphisms in OA via obesity. The purpose of this study was to determine the effects of FTO polymorphism rs8044769 alleles on OA in the temporomandibular joint (TMJ), which is minimally affected by body weight. MATERIALS AND METHODS: A total of 324 TMJs (113 with OA and 211 without OA, serving as controls) from 162 Japanese patients with temporomandibular disorders and undergoing MRI examination were analyzed. Genotyping was conducted, and multivariate analysis was performed after adjusting for the effects of age, sex, body mass index, and TMJ disc abnormalities. RESULTS: Mean age, BMI, and sex did not differ between the TMJs with OA and the TMJs without OA, but a significant difference was found for positional and dynamic disc abnormalities (P < 0.05). The allele frequency of FTO polymorphisms also differed significantly between the TMJs with OA and the TMJs without OA (P = 0.011). Moreover, logistic regression analysis showed no significant association between BMI (P = 0.581) and the occurrence of TMJOA but also indicated that the CC allele of rs8044769 is a risk factor for TMJOA (P = 0.040). CONCLUSIONS: Our results show that rs8044769 in the FTO gene might be involved in TMJOA. CLINICAL RELEVANCE: The present study provides a basis for a deeper understanding of the mechanism underlying degenerative skeletal diseases and the more effective selection and development of treatment strategies based on the patients' genetic characteristics.

Clinical manifestations of diffuse large B-cell lymphoma that exhibits initial symptoms in the maxilla and mandible: a single-center retrospective study.

BACKGROUND: Diffuse large B-cell lymphoma (DLBCL) is the most common type of lymphatic tumor; however, extranodal DLBCLs that exhibit initial symptoms in the maxilla and mandible are rare. Moreover, DLBCL is clinically classified as a moderate to highly malignant lymphatic tumor that can progress rapidly; therefore, early diagnosis is crucial. However, diagnosis is difficult as the disease causes a diverse range of clinical symptoms with no characteristic imaging findings. We conducted a clinical investigation to clarify the clinical characteristics of DLBCL that exhibits initial manifestation in the maxilla and mandible. METHODS: Of the 2748 patients with malignant tumors of the oral and maxillofacial region examined at our hospital during a period of 11 years between January 2006 and December 2016, 27 primary cases diagnosed with DLBCL based on the chief complaint of symptoms in the gingiva and bone of the maxilla and mandible were enrolled in this study. Evaluations were based on sex, age, whether treatment was provided by a previous physician, symptoms, duration of disease until treatment was sought, clinical diagnosis, laboratory findings, and imaging results. RESULTS: There were 15 cases that involved the maxilla and 12 that involved the mandible. The median duration of disease until treatment was sought was 60 d (3-450 d). All cases exhibited a tumor or a mass, and hypoesthesia of the chin was confirmed in eight cases wherein the mandible was involved. The clinical stages were stage I in eight cases, stage II in ten cases, and stage IV in nine cases. Serum lactate dehydrogenase (LDH) levels were elevated in 13 of 22 patients. The overall survival rate was 63%. CONCLUSIONS: Symptoms associated with nontender swelling and numbness of the lip or chin in the absence of other findings such as dental infections should raise suspicions about DLBCL. Patients should be provided appropriate imaging and accurate biopsy assessments to improve prognosis.

Buccinator and Mandibular Node Metastases in Oral Squamous Cell Carcinoma.

PURPOSE: The buccinator and mandibular nodes belong to the facial lymph node group, and metastasis of oral cancer to these nodes is extremely rare. The purpose of this study was to examine particularly rare metastatic cases in which treatment was administered for the buccinator or mandibular nodes. PATIENTS AND METHODS: The authors identified 1,479 cases of oral squamous cell carcinoma treated at their hospital from April 2001 to December 2016. After excluding cases with distant metastasis at initial treatment, perioperative mortality, and lack of follow-up data, the final study population consisted of 1,406 cases. RESULTS: Six patients were identified who had pathologic metastasis to the buccinator or mandibular node (3 men and 3 women; age range, 45 to 72 yr; average age, 59.3 yr). The primary sites were the lower gingiva in 2 cases and the buccal mucosa in 4 cases. There were 2 cases of metastasis to the buccinator nodes and 4 cases of metastasis to the mandibular nodes. There were no cases of metastasis to the buccinator and mandibular nodes. Each case also involved submandibular node metastasis. The outcomes were disease-free survival in 4 cases and death from cancer in 2 cases; the cumulative disease-specific 5-year survival rate was 62.5%. CONCLUSIONS: The possibility of metastasis to the buccinator and mandibular nodes should be considered in oral cancer when primary tumor invasion reaches the buccinator muscle with submandibular node metastasis.

Metastasis of lower gingival squamous cell carcinoma to buccinator lymph node: case report and review of the literature.

BACKGROUND: Metastasis of oral cancer to the buccinator lymph nodes (BN) is uncommon. The antegrade lymphatic flow in patients with normal anatomy and physiology makes metastasis of lower gingival cancer to BN unlikely. CASE PRESENTATION: A 67-year-old woman presented with a 46 × 25-mm tumor on her lower gingiva, along with metastatic foci in BN and cervical lymph nodes. After neoadjuvant chemotherapy, she underwent radical resection of the primary tumor and BN, along with neck dissection. Following surgery, she received adjuvant chemoradiotherapy. Two years after treatment, there has been no evidence of tumor recurrence or metastasis. CONCLUSION: This is the first report of lower gingival squamous cell carcinoma with metastasis to BN. Metastasis to BN from lower gingival cancer is very rare but should be considered in patients with locally advanced tumors or tumors that metastasize to the submandibular node.

Evaluation of the scatter doses in the direction of the buccal mucosa from dental metals.

The presence of dental metals creates radiation dose perturbation due to scattered radiation during radiation therapy for the head and neck region. The purpose of our study was to compare the scatter doses resulting from various dental metals in the direction of the buccal mucosa among a single-field technique, three-dimensional conformal radiation therapy (3D CRT), and intensity-modulated radiation therapy (IMRT) during radiation therapy for the head and neck region. We used nine metal cubes with 10 mm sides, which were placed inside a water phantom. The scatter doses from the cubes in the direction of the buccal mucosa were measured using radiochromic films. The films were placed perpendicularly to the surface of the cubes. The phantom was irradiated with a 4 MV photon energy by a linear accelerator for all techniques. In the single-field technique, the scatter doses from dental metals showed 3.7%-19.3% dose increases, and gold showed the largest dose increase. In 3D CRT, the scatter doses from dental metals showed 1.4%-6.9% dose increases, which were within the measurement uncertainty (except for gold). In IMRT, the scatter doses from dental metals showed only 1.4%-4.3% dose increases, which were all within the measurement uncertainty. During radiation therapy for the head and neck region, the scatter doses from the tested dental metals in the direction of the buccal mucosa in 3D CRT or IMRT were lower than those using the single-field technique. However, there were no differences between the scatter doses resulting from particular dental metals in the direction of the buccal mucosa in 3D CRT and those in IMRT, except for gold.

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.

Comparison of T2 values of the displaced unilateral disc and retrodiscal tissue of temporomandibular joints and their implications.

Unilateral anterior disc displacement (uADD) has been shown to affect the contralateral joints qualitatively. This study aims to assess the quantitative T2 values of the articular disc and retrodiscal tissue of patients with uADD at 1.5 Tesla (T). The study included 65 uADD patients and 17 volunteers. The regions of interest on T2 maps were evaluated. The affected joints demonstrated significantly higher articular disc T2 values (31.5 ± 3.8 ms) than those of the unaffected joints (28.9 ± 4.5 ms) (P < 0.001). For retrodiscal tissue, T2 values of the unaffected (37.8 ± 5.8 ms) and affected joints (41.6 ± 7.1 ms) were significantly longer than those of normal volunteers (34.4 ± 3.2 ms) (P < 0.001). Furthermore, uADD without reduction (WOR) joints (43.3 ± 6.8 ms) showed statistically higher T2 values than the unaffected joints of both uADD with reduction (WR) (33.9 ± 3.8 ms) and uADDWOR (38.9 ± 5.8 ms), and the affected joints of uADDWR (35.8 ± 4.4 ms). The mean T2 value of the unaffected joints of uADDWOR was significantly longer than that of healthy volunteers (P < 0.001). These results provided quantitative evidence for the influence of the affected joints on the contralateral joints.

Cross-sectional and longitudinal assessment of subchondral cysts in temporomandibular joints: Clinical and MRI study with a mean follow-up of 66 months.

PURPOSE: This observational study aimed to elucidate the pathophysiology of subchondral cysts (SC) in the temporomandibular joint (TMJ) and examine the results of conservative therapy administered to patients with SCs in the TMJ. METHODS: The study included 41 patients with SCs, extracted from 684 consecutive patients who underwent magnetic resonance imaging (MRI). The anatomical features of SCs and positional abnormalities of the articular disc were initially evaluated using MRI. A second MRI examination was performed for 28/41 patients at 40-107 months (mean, 66 months) after the first MRI. The joint space, anteroposterior width of the condylar head (WiC), articular eminence angle (AEA), and visual analog scale of jaw pain (VAS) were assessed alongside the MRI examinations. RESULTS: Most SCs were present in the anterosuperior and central condyle. Disc displacement was observed in 100% of 42 TMJs with SCs. Of the 29 joints in 28 patients, SCs in 19 joints resolved with time, whereas SCs in 10 joints persisted. A significant increase in the WiC and a significant decrease in AEA and VAS scores were observed on the second MRI scan. CONCLUSIONS: SCs tended to form in the anterosuperior and central parts of the condyle, where mechanical loading was likely to be applied. SCs are strongly associated with articular disc displacement. Two-thirds of SCs resolved over time, accompanied by resorption and osteophytic deformation of the condyle. SC might not be an indicator for the start of surgical treatment, and nonsurgical treatment could improve the clinical symptoms of patients with SCs.

MR appearance of a rare ameloblastic fibroma with formation of dental hard tissues with histopathologic correlation: a case report.

An ameloblastic fibroma with formation of dental hard tissues, which the classical name is ameloblastic fibro-odontoma (AFO), is a rare type of mixed odontogenic tumor. An 8-year-old boy was diagnosed with AFO, with an inhomogeneous high signal within the lesion shown by T2-weighted magnetic resonance imaging (MRI). Computed tomography (CT) imaging revealed a unilocular low CT value area of 24 × 19 × 26 mm with buccolingual bony expansion and cortical bone thinning on the left side of the mandible including the crown of the mandibular left second molar. In addition, multiple calcified bodies were detected within the lesion, one of which had a CT value of approximately 2200 HU, equivalent to that of enamel. MRI indicated the lesion to be sized 24 × 19 × 25 mm along with buccolingual bony expansion in the left side of the mandible. Additionally, the lesion showed an internal inhomogeneous high signal, while a portion had an especially high signal in T2-weighted images. That particularly high signal area coincided with the nodular growth area of mucus-rich mesenchymal components without the epithelial component in histopathology findings. The particularly high signal revealed by T2-weighted imaging could be attributed to the mucus-rich component. MRI was found useful for revealing differences in the internal histopathological properties of an AFO in our patient.

Inverse planning optimization with lead block effectively suppresses dose to the mandible in high-dose-rate brachytherapy for tongue cancer.

PURPOSE: In this study, we developed in-house software to evaluate the effect of the lead block (LB)-inserted spacer on the mandibular dose in interstitial brachytherapy (ISBT) for tongue cancer. In addition, an inverse planning algorithm for LB attenuation was developed, and its performance in mandibular dose reduction was evaluated. METHODS: Treatment plans of 30 patients with tongue cancer treated with ISBT were evaluated. The prescribed dose was 54 Gy/9 fractions. An in-house software was developed to calculate the dose distribution based on the American Association of Physicists in Medicine (AAPM) Task Group No.43 (TG-43) formalism. The mandibular dose was calculated with consideration of the LB attenuation. The attenuation coefficient of the lead was computed using the PHITS Monte Carlo simulation. The software further optimized the treatment plans using an attraction-repulsion model (ARM) to account for the LB attenuation. RESULTS: Compared to the calculation in water, the D2 cc of the mandible changed by - 2.4 ± 2.3 Gy (range, - 8.6 to - 0.1 Gy) when the LB attenuation was considered. The ARM optimization with consideration of the LB resulted in a - 2.4 ± 2.4 Gy (range, - 8.2 to 0.0 Gy) change in mandibular D2 cc. CONCLUSIONS: This study enabled the evaluation of the dose distribution with consideration of the LB attenuation. The ARM optimization with lead attenuation further reduced the mandibular dose.

Radiation-induced undifferentiated spindle cell sarcoma following high-dose-rate interstitial brachytherapy for tongue squamous cell carcinoma.

High-dose-rate interstitial brachytherapy (HDR-ISBT) has recently come to be considered one of the most effective treatments for oral cancer. On the other hand, it is important to note that radiation therapy has some side effects. Especially, radiation-induced malignancy is probably the most serious complication affecting long-term survivors. We report a case of a radiation-induced undifferentiated spindle cell sarcoma that developed following HDR-ISBT for tongue squamous cell carcinoma (SCC). A 39-year-old woman with right tongue SCC underwent HDR-ISBT (60 Gy, 10 fractions, 8 days) treatment. Five years and one month later, a tumor had developed at the primary site. Surgery was performed for the tumor, which was histopathologically diagnosed as an undifferentiated spindle cell sarcoma. That was distinct from the squamous cell origin of the primary cancer. According to recently established criteria for radiation-induced malignancy, this case was classified as a radiation-induced sarcoma. A search of the literature revealed no previous report of radiation-induced malignancy following HDR-ISBT for tongue cancer.

Correlation between pixel values in a cone-beam computed tomographic scanner and the computed tomographic values in a multidetector row computed tomographic scanner.

OBJECTIVES: The study's objectives were to investigate the correlation between pixel values obtained from a cone-beam computed tomographic (CBCT) scanner and the computed tomographic (CT) values from a multidetector row CT scanner and to determine whether they have a linear relationship at various tube voltages and tube currents. METHODS: A phantom with different concentrations of contrast medium at the center of a multidetector row CT and a CBCT scanner was scanned at various imaging parameters. Computed tomographic values and pixel values were measured using ImageJ. Regression analysis was performed, as well as correlation tests with a Pearson correlation coefficient. RESULTS: A significant correlation between pixel values and the CT values of the same specimen was observed (P < 0.0001), and a linear relationship was found between the values from the 2 scanners at each parameter. CONCLUSIONS: A high correlation and linear relationship between the CT values and pixel values were found at each parameter. Therefore, linear functions can be used to convert a pixel value from the CBCT machine used in this study to the CT values.

Distant metastasis from oral cavity-correlation between histopathology results and primary site.

OBJECTIVES: Oral cancer is the eighth most common type of cancer worldwide and a significant contributor to the global burden caused by this disease. The principal parameters considered to influence prognosis, and thus treatment selection, are size and location of the primary tumor, as well as assessment of the presence and extent of lymph node and distant metastasis (DM). However, no known report regarding the relationship between the primary site and DM has been presented. For effective treatment selection and good prognosis, the correlation of DM with anatomic site and histopathology results of the primary malignancy is important. In the present study, we performed a systematic review of published reports in an effort to determine the relationship between the anatomic site of various types of oral cavity cancer and DM. METHODS: A systematic review of articles published until the end of 2018 was performed using PubMed/MEDLINE. RESULTS: A total of 150 studies were selected for this review. The percentage of all cases reported with DM was 6.3%, ranging from 0.6% to 33.1% in the individual studies. The rate of incidence of tongue occurrence was 9.3%. A frequent DM site was the lungs, with adenoid cystic carcinoma the most commonly involved histopathological factor. Malignant melanoma was most frequent (43.4%) in all histopathology findings, whereas there were no cases with an acinic cell carcinoma or cystadenocarcinoma. CONCLUSIONS: We found that the occurrence of DM from the primary site as well as rate of incidence was dependent on histopathological factors.

Mandibular Reconstruction with Scapular Systems: A Single-Center Case Series Involving 208 Flaps.

BACKGROUND: The scapular flap is the most versatile composite flap used for mandibular reconstruction. The purpose of this study was to review and summarize findings of cases of mandibular reconstruction with a scapular flap and describe associated outcomes and complications. METHODS: A total of 208 microvascular scapular free flaps were performed for mandibular reconstruction in a total of 205 patients from 2003 to 2018. This study involved a retrospective review of all eligible patients' medical records. RESULTS: There were seven cases (3.4 percent) of microvascular thrombosis. Postoperative bone union was achieved by 201 patients, except for five with total flap necrosis and two with partial flap necrosis. There were four cases (1.9 percent) of mandibular condyle dislocation. Two major types of complications were observed at the donor site, including four cases of infection and six cases of scapular body fracture. Postoperative denture prosthesis was introduced to 97 patients (47.3 percent). Implant treatment was performed in 10 patients (4.9 percent). Functional and aesthetic outcomes were good to excellent. CONCLUSIONS: The scapular composite free flap for mandibular reconstruction was associated with favorable outcomes and demonstrated satisfactory results. Although scapular bone fracture is rare, patients who have undergone mandibular reconstruction using a scapular flap should be monitored for its presence. . CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Surgical treatment for oral tongue squamous cell carcinoma: A retrospective study of 432 patients.

The incidence of oral cancer in Japan accounts for 1% of all cancers, with oral tongue cancer accounting for 60% of oral cancers based on the subsite. The most common histologic type is squamous cell carcinoma. This study aimed to evaluate the series of surgical treatments for 432 patients with oral tongue squamous cell carcinoma (OTSCC). Initial surgical treatments for the primary site included partial glossectomy, hemiglossectomy, and total or subtotal glossectomy in 348, 58, and 26 patients, respectively. Therapeutic neck dissection, elective neck dissection, and subsequent neck dissection were performed in 74, 53, and 37 patients, respectively. Patients with advanced cases had level IIb, IV, and V metastasis and outside regional lymph node metastases. The cumulative 5-year disease-specific survival rate for OTSCC was 92.8%, and the rates for each stage were 96.6%, 93.9%, 84.1%, and 79.0% in stages I, II, III, and IV, respectively. The recurrence rate, overall salvage rate for recurrent cases, and rate for the additional surgical group were 10.4%, 46.7%, and 78.6%, respectively. Patients with multiple cervical lymph node metastases, extranodal extension, metastases to multiple levels, and lower neck metastases had poor prognosis. In conclusion, careful follow-up is necessary to detect recurrence of primary tumors at a stage when surgical treatment can be performed, and cervical lymph node status is one of the most important prognostic factors in OTSCC.

Risk factors for distant metastasis in locoregionally controlled oral squamous cell carcinoma: a retrospective study.

The control of distant metastasis in oral squamous cell carcinoma is an important determinant of improved prognosis. The study aimed to identify risk factors for distant metastasis in patients with locoregionally controlled oral carcinoma. We identified 982 patients with oral squamous cell carcinoma treated at our hospital between January 2008 and December 2017. After excluding patients with distant metastasis at initial treatment, patients with metastasis to the oral cavity, those receiving palliative treatment, and those lacking follow-up data, 941 patients were selected. Finally, among these 941 patients, 887 with locoregionally controlled oral squamous cell carcinoma were included in the study. Among the 887 patients, 36 had confirmed distant metastasis (4.1%), and the lung was the most common site (31/36 patients, 86.1%). Multivariate analysis showed that the incidence of primary intraosseous carcinoma of the mandible, cervical lymph node metastasis at levels IV and V, and the presence of pathological extranodal extension were significant risk factors for distant metastasis. When treating patients with oral squamous cell carcinoma who are positive for the aforementioned risk factors, the possibility of developing distant metastases must be accounted for, and aggressive treatment should be planned accordingly.

Multicenter retrospective analysis of clinicopathological features and prognosis of oral tongue squamous cell carcinoma in adolescent and young adult patients.

ABSTRACT: The aim of this study is to report the differences in clinicopathological features of oral tongue squamous cell carcinoma (OTSCC) and survival between adolescent and young adult (AYA) patients and elderly patients and to find the prognosticators. The medical records of 101 AYA patients and 175 control patients with OTSCC who underwent surgery were reviewed. Variables related to prognosis and their clinicopathological associations were analyzed. The 5-year overall survival (5y-OS) rates of AYA and control patients with stage I and II OTSCC were 94.4% and 89.6% (P = .353), respectively, and their 5-year disease-free survival (5y-DFS) rates were 82.0% and 76.6%, respectively (P = .476). The 5y-OS rates of patients with stages III and IV OTSCC were 83.3% and 66.7% (P = .333), respectively, and their 5y-DFS rates were 75.0% and 57.1% (P = .335), respectively. Logistic regression analysis revealed that there was no significant clinicopathological difference in AYA and control group. Furthermore, there was no significant difference in 5y-OS rates between patients who underwent elective neck dissection (END) and those who underwent therapeutic neck dissection (TND) in both group (P = 0.717 and 0.688). Overall, the present study revealed the clinicopathological features and prognosis of OTSCC were similar in AYA patients and elderly patients. Moreover, as there was no significant difference in OS between patients who underwent END and those who underwent TND in AYA and control groups, our results suggest that the indication for END in AYA patients with clinical N0 OTSCC is similar to that for elderly patients.

Comparison of Clinicopathological Characteristics Between the Anterior and Posterior Type of Squamous Cell Carcinoma of the Floor of the Mouth: The Anterior Type Is a Risk Factor for Multiple Primary Cancer.

BACKGROUND: Floor of the mouth (FOM) squamous cell carcinoma (SCC) accounts for approximately 10% of all oral SCCs. FOM SCC can be classified into the anterior and posterior types according to their site of origin, but few studies have compared these types. This study sought to clarify differences in clinicopathological characteristics between these two types. METHODS: A total of 1,220 patients with oral SCC were treated at our department from January 2001 to December 2015. Among these patients, 62 had FOM SCC. The FOM SCCs were classified into two groups: the anterior type and the posterior type. The anterior and posterior types were defined by the boundary connecting the spaces between the canine and the first premolar bilaterally. We retrospectively compared the sex, age, smoking and drinking history, clinical stage, treatment, histopathological diagnosis, multiple primary cancers, and outcomes of the two groups. RESULTS: Among the 62 patients, 32 had the anterior type, while 30 had the posterior type. The anterior type was found more significantly in men (p = 0.01) and individuals with a smoking history than the posterior type (p = 0.04). pN2-3 cervical lymph node metastasis was significantly more common in the anterior type than in the posterior type (p = 0.01). The median depth of invasion in the anterior type was 4 mm. Multivariate analysis showed that the anterior type was an independent risk factor for multiple primary cancer development in FOM SCC (p = 0.02). The cumulative 10-year disease-specific survival rates of the anterior and posterior types were 92.8 and 95.0%, respectively, while the overall survival rates were 65.4 and 95.0%, respectively. In the anterior type FOM SCC, a lower overall survival rate was associated with multiple primary cancers and smoking-related diseases. CONCLUSION: Smoking cessation and adequate systemic screening for multiple primary cancers are needed to improve the prognosis of FOM SCC, particularly the anterior type.

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.