[A Case of Severe Skin Disorder during Pembrolizumab Treatment for Recurrent Maxillary Gingival Carcinoma]

Immune checkpoint inhibitors are known to produce immune-related adverse events(irAE)that require medical management. Herein, we report a case of a patient treated with pembrolizumab who experienced a Grade 3 interrupted skin disorder. The patient is a 67-year-old female diagnosed with right maxillary gingival squamous cell carcinoma(cT4aN0M0, Stage ⅣA)and underwent partial right maxillectomy, right extended supra-omohyoid neck dissection, and maxillary reconstruction using a forearm flap. Six months postoperatively, late lymph node metastases with extracapsular spread was found in the right buccal lymph node and the left neck, and the patient underwent right buccal lymphadenectomy and left modified radical neck dissection. After postoperative combined chemoradiotherapy(cisplatin plus IMRT)followed by 13 courses of cetuximab plus paclitaxel, a recurrent lesion was found in the right buccal region. After 8 courses of pembrolizumab, a skin rash appeared on the forearm, chest, and back, which was diagnosed as Grade 3 irAE, requiring hospitalization. The patient was re-instituted after waiting for improvement of the skin disorder. The pembrolizumab at 75% reduction dose was re-administrated, and the patient has been followed up so far.

Numb Chin Syndrome as the Initial Presentation of Mandibular Metastasis of Colorectal Cancer: A Case Report

Numb chin syndrome (NCS) is hypesthesia of the mandible and lower lip caused by damage to the inferior alveolar or mandibular nerves, commonly due to dental treatment or osteomyelitis, but occasionally caused by malignant tumors. We report the case of a male in his 60s. He came to our hospital with a chief complaint of mandibular pain and paresthesia in the right side of the mental region. He had noticed swelling of the left mandible one month before the initial visit and strong hypesthesia of the right side of the mental region one week before the initial visit. Panoramic radiographs showed slight osteosclerosis of the left side mandible at the initial visit. Blood tests showed only a slight inflammatory reaction. The diagnosis of mandibular osteomyelitis and numb chin syndrome was made, and a contrast-enhanced CT scan was performed to investigate the possibility of neoplastic lesions, but no obvious cause was found. Osteosclerosis was minimal. A tissue biopsy was recommended, but the patient did not consent. Considering the possibility of NCS due to a hematologic disorder, the patient was referred to a hematologist, but no cause could be identified at the initial visit. With time, the markedly severe pain worsened, and the possibility of a neoplastic lesion was again suspected. Blood tests were performed, which revealed abnormally high levels of CA19 and CEA. He consulted a gastroenterologist, who found a tumor in the ileocecal region on contrast-enhanced CT, and multiple systemic metastases were found on a PET-CT scan the next day. Systemic chemotherapy was administered for multiple metastatic unresectable colorectal cancer (cT4N1aMc2 stage IVc).

Novel mechanism of cisplatin resistance in head and neck squamous cell carcinoma involving extracellular vesicles and a copper transporter system

BACKGROUND

Cisplatin (CDDP) plays a central role in chemotherapy for head and neck squamous cell carcinoma (HNSCC), but drug resistance in HNSCC chemotherapy remains a problem, and the mechanism of CDDP resistance is unclear. We investigated CDDP-resistance mechanisms mediated by extracellular vesicles (EVs) and ATPase copper transporting beta (ATP7B) in HNSCC.

METHODS

We established CDDP-resistant sublines of HNSCC cells and verified their ATP7B expression. We used an EV secretion inhibitor (GW4869) and ATP7B short hairpin (sh)RNA transfection to examine the correlation between EV secretion and ATP7B expression.

RESULTS

The CDDP-resistant HNSCC sublines showed decreased CDDP sensitivity and increased ATP7B expression. GW4869 suppressed ATP7B expression, and ATP7B shRNA transfection suppressed EV secretion. The suppressions of EV secretion and ATP7B expression both enhanced CDDP's cell-killing effect.

CONCLUSIONS

EVs were involved in the ATP7B-mediated mechanism underlying CDDP resistance. Further clarification of the EV-induced CDDP-resistance mechanism may lead to novel therapeutic strategies for HNSCC.

In Vivo Evaluation of Bone Regenerative Capacity of the Novel Nanobiomaterial: β-Tricalcium Phosphate Polylactic Acid-co-Glycolide (β-TCP/PLLA/PGA) for Use in Maxillofacial Bone Defects

Maxillofacial bone defects are treated by autografting or filling with synthetic materials in various forms and shapes. Electrospun nanobiomaterials are becoming popular due to their easy placement and handling; combining ideal biomaterials extrapolates better outcomes. We used a novel electrospun cotton-like fiber made from two time-tested bioresorbable materials, β-TCP and PLLA/PGA, to check the feasibility of its application to maxillofacial bone defects through an in vivo rat mandibular bone defect model. Novel β-TCP/PLLA/PGA and pure β-TCP blocks were evaluated for new bone regeneration through assessment of bone volume, inner defect diameter reduction, and bone mineral density. Bioactive/osteoconductivity was checked by scoring the levels of Runt-related transcription factor x, Leptin Receptor, Osteocalcin, and Periostin biomarkers. Bone regeneration in both β-TCP/PLLA/PGA and β-TCP was comparable at initial timepoints. Osteogenic cell accumulation was greater in β-TCP/PLLA/PGA than in β-TCP at initial as well as late phases. Periostin expression was more marked in β-TCP/PLLA/PGA. This study demonstrated comparable results between β-TCP/PLLA/PGA and β-TCP in terms of bone regeneration and bioactivity, even with a small material volume of β-TCP/PLLA/PGA and a decreased percentage of β-TCP. Electrospun β-TCP/PLLA/PGA is an ideal nanobiomaterial for inducing bone regeneration through osteoconductivity and bioresorbability in bony defects of the maxillofacial region.

[Effect of the Hyoid Bone Suspension Technique on the Preservation of Swallowing Function after Total Glossectomy and Pectoralis Major Musculocutaneous Flap Reconstruction for Locally Advanced Tongue Cancer]

Dysphagia is a major postoperative complication in patients with locally advanced oral cancer. In this case report, we describe the effect of the hyoid bone suspension technique on the preservation of swallowing function after total glossectomy and pectoralis major musculocutaneous flap reconstruction for locally advanced tongue cancer. Case: A 72-year-old Japanese male was diagnosed with advanced squamous cell carcinoma on the left side of his tongue(cT4aN2cM0, cStage ⅣA). Under general anesthesia, the patient underwent a tracheotomy, bilateral modified radical neck dissection type Ⅲ, total glossectomy, and reconstruction with a left pectoralis major musculocutaneous flap(PMMC flap). Intraoperatively, the PMMC flap was designed to have a heart shape of 11×6 cm and was elevated. Subsequently, holes were made at the lower edge of the mandible, and the hyoid bone was suspended and fixed to the mandibular border using 2-0 nylon sutures. The postoperative course was uneventful; the flap was completely engrafted and was in good condition. The hyoid bone suspension technique can reproduce the pharyngeal phase of swallowing, and the palatal augmentation prosthesis helps to improve food mass feeding and preserve the swallowing function.

[Case of Tongue Cancer That Was Considered to Be a Metachronous Double Cancer with Parotid Gland Cancer]

In Japan, the incidence of double cancers is increasing due to the rise in cancer prevalence in the super-aging society, and the frequency is particularly high among patients with head and neck cancer. To the best of our knowledge, there has been only 1 reported case of metachronous double cancer with parotid gland cancer and tongue squamous cell carcinoma, and herein we report the outline of this case. The patient was a 70-year-old male with a smoking history. In 2017, a total parotidectomy and neck dissection for adenocarcinoma of the right parotid gland were performed at the otolaryngology department, followed by concurrent chemoradiotherapy as postoperative therapy. Pathological examination revealed adenocarcinoma NOS(pT4aN2bM0, Stage ⅣA). There was no recurrence or metastasis, and the patient was recovering well. However, in October 2022, the patient presented to the hospital with a chief complaint of pain at the right margin of the tongue. At the initial consultation, an ulcerative lesion with a slightly unclear boundary and maximum diameter of approximately 15 mm was observed on the right margin of the tongue. Since epithelialization was observed in some regions, it was diagnosed as intractable stomatitis and the patient was put under observation for the time being. With no signs of healing during the follow- up examination a month later and considering the possibility of malignant tumors, a total excision of tongue lesion was performed. Pathological examination revealed well-differentiated squamous cell carcinoma(pT1N0M0, Stage Ⅰ). Going forward, we plan to conduct careful follow-up observations with the possibility of further metachronous double cancer occurrences in mind.

[Two Cases of Advanced Lower Gingival Carcinoma Treated Surgically Using a Novel Patient-Specific Full Custom- Made Mandibular Reconstruction Plate System]

The treatment of advanced lower gingival carcinoma requires postoperative chemoradiotherapy; therefore, simultaneous hard-tissue reconstruction may not be indicated. In these cases, mandibular reconstruction is performed using a temporal reconstruction plate and various skin flaps. Herein, we reported 2 cases of advanced lower gingival carcinoma treated with a novel computer-assisted patient-specific, fully custom-made mandibular reconstruction plate system(Cosmofix®)in combination with a pedicle/free flap. In case 1, an 80-year-old female patient was diagnosed with right lower gingival carcinoma( cT4aN3bM0, Stage ⅣB). Under general anesthesia, she underwent tracheostomy, bilateral neck dissection, segmental mandibulectomy, and mandibular reconstruction using Cosmofix® in combination with an ulnar forearm free flap. In case 2, an 81-year-old male patient was diagnosed with right lower gingival carcinoma(cT4aN2bM0, Stage ⅣA). The patient underwent maintenance dialysis and required minimally invasive surgery using a pedicle flap. Under general anesthesia, the patient underwent tracheostomy, right modified radical neck dissection, segmental mandibulectomy, and mandibular reconstruction using Cosmofix® in combination with a pectoralis major myocutaneous flap. Postoperative facial morphology, occlusion, eating, swallowing, articulation, and other dysfunctions were minimal in both the cases. Adjuvant chemoradiotherapy was recommended. In conclusion, the utilization of the Cosmofix® system enabled both esthetic and functional reconstruction following segmental mandibulectomy for advanced lower gingival carcinoma.

[A Case of Recurrent Tongue Cancer in a Patient of AYA Generation Who Underwent Salvage Surgery and Oral-Maxillofacial Reconstruction after Super-Selective Intra-Arterial Chemoradiotherapy]

Radical tumor resection for oral cancer can cause morphological and esthetic disorders and oral and maxillofacial dysfunction and maintaining a social life could become challenging, especially in the adolescents and young adults(AYA)generation. Conversely, chemoradiotherapy for young patients may cause adverse reactions such as impaired fertility and late side effects of radiation. Therefore, treatment should be performed cautiously. We report a case of AYA generation patient who underwent salvage surgery and maxillofacial reconstruction for recurrent tongue cancer after super-selective intra-arterial chemoradiotherapy. The patient was a 30-year-old woman who was 20 weeks pregnant. She was diagnosed with Stage Ⅲ squamous cell carcinoma of the right tongue, cT3N0M0. After abortion, the patient underwent super-selective intra-arterial chemoradiotherapy and achieved a complete response. However, 13 years later, a recurrence of Stage ⅣA tongue cancer, r- cT4aN2bM0, was reported. Additionally, the patient had osteoradionecrosis. We performed radical tumor resection(bilateral neck dissection plus subtotal glossectomy plus segmental mandibulectomy)and maxillofacial reconstruction with a fibula flap. Subsequently, we performed occlusal reconstruction treatment using dental implants. Three years postoperatively, no tumor recurrence was observed, and the patient was satisfied with the restored morpho-aesthetic and maxillo-oral functions.

Preservation of the Nerve to the Mylohyoid Muscle During Submental Island Flaps: An Anatomic Feasibility Study for Facial Nerve Reanimation Procedures

The submental island flap is an axial pattern pedicle flap widely used in head and neck surgery because of its ease and success. Indications of the submental island flap range from reconstruction for the malignant tumor resection to loss of temporal bone and facial skin due to trauma. Whereas, intraoperative facial nerve injury is not uncommon. We verified whether it was possible to localize the nerve to the mylohyoid muscle and reanimate the facial nerve during submental island flap procedures by preserving the mylohyoid muscle using human fresh cadaveric specimens. Six cadaveric heads were dissected and the position of the nerve to the mylohyoid muscle identified to the mylohyoid triangle documented. We identified the nerve to the mylohyoid muscle on all sides within the mylohyoid triangle and were able to separate the nerve from the submental island flap completely. Our results suggest that facial nerve reanimation using the nerve to the mylohyoid muscle can be used while reconstructing with a submental island flap in cases of intraoperative facial nerve injury.

The acid-sensing nociceptor TRPV1 controls breast cancer progression in bone via regulating HGF secretion from sensory neurons

Cancers showing excessive innervation of sensory neurons (SN) in their microenvironments are associated with poor outcomes due to promoted growth, increased tumor recurrence, metastasis, and cancer pain, suggesting SNs play a regulatory role in cancer aggressiveness. Using a preclinical model in which mouse 4T1 breast cancer (BC) cells were injected into the bone marrow of tibiae, we found 4T1 BC cells aggressively colonized bone with bone destruction and subsequently spread to the lung. Of note, 4T1 BC colonization induced the acidic tumor microenvironment in bone in which SNs showed increased innervation and excitation with elevated expression of the acid-sensing nociceptor transient receptor potential vanilloid-1 (TRPV1), eliciting bone pain (BP) assessed by mechanical hypersensitivity. Further, these excited SNs produced increased hepatocyte growth factor (HGF). Importantly, the administration of synthetic and natural TRPV1 antagonists and genetic deletion of TRPV1 decreased HGF production in SNs and inhibited 4T1 BC colonization in bone, pulmonary metastasis from bone, and BP induction. Our results suggest the TRPV1 of SNs promotes BC colonization in bone and lung metastasis via up-regulating HGF production in SNs. The SN TRPV1 may be a novel therapeutic target for BC growing in the acidic bone microenvironment and for BP.

A rare case of dentinogenic ghost cell tumor with concomitant odontoma

Key Clinical Message

A case of dentinogenic ghost cell tumor occurring simultaneously with a clinically diagnosed odontoma. The occurrence of epithelial and mesenchymal tumors at the same site is very rare, but should be kept in mind during pathological diagnosis.

Abstract

Dentinogenic ghost cell tumor (DGCT) is a rare and benign odontogenic tumor composed of ghost cells, calcified tissue, and dentin. We present an extremely rare case of a 32-year-old female who was clinically diagnosed with an odontoma presenting with a painless swelling in her maxilla. Radiographic examination showed a well-defined radiolucent lesion with tooth-like calcified areas. The tumor was resected under general anesthesia. No recurrence was noted at the 12-month follow-up. Histopathological examination of the surgically resected tumor yielded a diagnosis of DGCT with odontoma.

EpEX, the soluble extracellular domain of EpCAM, resists cetuximab treatment of EGFR-high head and neck squamous cell carcinoma

OBJECTIVES

Cetuximab (Cmab) is a molecularly targeted monoclonal antibody drug for head and neck squamous cell carcinoma (HNSC), although cetuximab resistance is a serious challenge. Epithelial cell adhesion molecule (EpCAM) is an established marker for many epithelial tumors, while the soluble EpCAM extracellular domain (EpEX) functions as a ligand for epidermal growth factor receptor (EGFR). We investigated the expression of EpCAM in HNSC, its involvement in Cmab action, and the mechanism by which soluble EpEX activated EGFR and played key roles in Cmab resistance.

MATERIALS AND METHODS

We first examined EPCAM expression in HNSCs and its clinical significance by searching gene expression array databases. We then examined the effects of soluble EpEX and Cmab on intracellular signaling and Cmab efficacy in HNSC cell lines (HSC-3 and SAS).

RESULTS

EPCAM expression was found to be enhanced in HNSC tumor tissues compared to normal tissues, and the enhancement was correlated with stage progression and prognosis. Soluble EpEX activated the EGFR-ERK signaling pathway and nuclear translocation of EpCAM intracellular domains (EpICDs) in HNSC cells. EpEX resisted the antitumor effect of Cmab in an EGFR expression-dependent manner.

CONCLUSION

Soluble EpEX activates EGFR to increase Cmab resistance in HNSC cells. The EpEX-activated Cmab resistance in HNSC is potentially mediated by the EGFR-ERK signaling pathway and the EpCAM cleavage-induced nuclear translocation of EpICD. High expression and cleavage of EpCAM are potential biomarkers for predicting the clinical efficacy and resistance to Cmab.

The Role of Hedgehog Signaling in the Melanoma Tumor Bone Microenvironment

A crucial regulator in melanoma progression and treatment resistance is tumor microenvironments, and Hedgehog (Hh) signals activated in a tumor bone microenvironment are a potential new therapeutic target. The mechanism of bone destruction by melanomas involving Hh/Gli signaling in such a tumor microenvironment is unknown. Here, we analyzed surgically resected oral malignant melanoma specimens and observed that Sonic Hedgehog, Gli1, and Gli2 were highly expressed in tumor cells, vasculatures, and osteoclasts. We established a tumor bone destruction mouse model by inoculating B16 cells into the bone marrow space of the right tibial metaphysis of 5-week-old female C57BL mice. An intraperitoneal administration of GANT61 (40 mg/kg), a small-molecule inhibitor of Gli1 and Gli2, resulted in significant inhibition of cortical bone destruction, TRAP-positive osteoclasts within the cortical bone, and endomucin-positive tumor vessels. The gene set enrichment analysis suggested that genes involved in apoptosis, angiogenesis, and the PD-L1 expression pathway in cancer were significantly altered by the GANT61 treatment. A flow cytometry analysis revealed that PD-L1 expression was significantly decreased in cells in which late apoptosis was induced by the GANT61 treatment. These results suggest that molecular targeting of Gli1 and Gli2 may release immunosuppression of the tumor bone microenvironment through normalization of abnormal angiogenesis and bone remodeling in advanced melanoma with jaw bone invasion.

Cancer-nerve interplay in cancer progression and cancer-induced bone pain

INTRODUCTION

Cancer-induced bone pain (CIBP) is one of the most common and debilitating complications associated with bone metastasis. Although our understanding of the precise mechanism is limited, it has been known that bone is densely innervated, and that CIBP is elicited as a consequence of increased neurogenesis, reprogramming, and axonogenesis in conjunction with sensitization and excitation of sensory nerves (SNs) in response to the noxious stimuli that are derived from the tumor microenvironment developed in bone. Recent studies have shown that the sensitized and excited nerves innervating the tumor establish intimate communications with cancer cells by releasing various tumor-stimulating factors for tumor progression.

APPROACHES

In this review, the role of the interactions of cancer cells and SNs in bone in the pathophysiology of CIBP will be discussed with a special focus on the role of the noxious acidic tumor microenvironment, considering that bone is in nature hypoxic, which facilitates the generation of acidic conditions by cancer. Subsequently, the role of SNs in the regulation of cancer progression in the bone will be discussed together with our recent experimental findings.

CONCLUSION

It is suggested that SNs may be a newly-recognized important component of the bone microenvironment that contribute to not only in the pathophysiology of CIBP but also cancer progression in bone and dissemination from bone. Suppression of the activity of bone-innervating SNs, thus, may provide unique opportunities in the treatment of cancer progression and dissemination, as well as CIBP.

Postoperative Complications following Open Reduction and Rigid Internal Fixation of Mandibular Condylar Fracture Using the High Perimandibular Approach

The high perimandibular approach is a feasible surgical technique for treating mandibular condylar fractures with open reduction and internal fixation, followed by fewer complications. Temporary trismus is the only postoperative complication that may occur. This study evaluated postoperative complications following open reduction and rigid internal fixation (OR-IF) of mandibular condylar fractures using the high perimandibular approach. Twenty consecutive patients undergoing OR-IF were included in this study. They included 11 male and 9 female patients, of an average age of 58.5 years, all of whom responded to a follow-up call at least 12 months after the surgery. All patients were evaluated for range of mouth opening, postoperative complications, and radiological findings. A statistical analysis of the relationship between range of mouth opening and related clinical parameters at 6 months postoperative evaluation was conducted. The fracture of the condylar neck was associated with a limited range of mouth opening and longer operation time. However, longer operation time was not associated with a limited range of mouth opening. The high perimandibular approach with OR-IF in mandibular condylar fractures is a feasible and safe technique; however, prolonged surgery and mandibular condylar neck fractures could affect the postoperative range of mouth opening.

[A Case of Reconstruction of the Osteoradionecrosis of the Jaw Using the Patient-Specific Custom-Made Cutting Guide and Mandibular Reconstruction Plate]

Multidisciplinary treatment, combining ablative surgery and reconstruction, radiotherapy, and chemotherapy, is used to treat advanced oral cancers. In this study, we report a case of extensive osteoradionecrosis of the mandible following multidisciplinary treatment for tongue cancer, in which a computer-assisted, patient-specific custom-made cutting guide and reconstruction plate(TruMatch® )were used to improve the patient's facial morphology and oral-maxillofacial functioning. A 70-year-old man received multidisciplinary treatment for squamous cell carcinoma of the left side of the tongue (cT3N2bM0, cStage ⅣA)at a previous hospital. Seven years postoperatively, bilateral osteoradionecrosis of the mandible developed, and the patient was referred to our department for further treatment. Since the lesions were extensive, we planned reconstructive surgery using the TruMatch® system in collaboration with the plastic surgery department of our hospital. Surgery was performed precisely and accurately according to the preoperative simulation. Postoperatively, the patient's recovery was uneventful. The TruMatch® system enables us to achieve good morphological and comprehensive functional oral-maxillofacial reconstruction.

Lactate secreted via MCT4 from bone‑colonizing breast cancer excites sensory neurons via GPR81

Breast cancer (BC) bone metastasis causes bone pain (BP), which detrimentally damages the quality of life and outcome of patients with BC. However, the mechanism of BC‑BP is poorly understood, and effective treatments are limited. The present study demonstrated a novel mechanism of BC‑BP using a mouse model of bone pain, in which mouse (EO771) and human (MDA‑MB‑231) BC cells were injected in the bone marrow cavity of tibiae. Western blot analysis using sensory nerves, in vivo assessment of cancer pain and in vitro calcium flux analysis were performed. These mice developed progressive BC‑BP in tibiae in conjunction with an upregulation of phosphorylated pERK1/2 and cAMP‑response element‑binding protein (pCREB), which are molecular indicators of neuron excitation, in the dorsal root ganglia (DRG) of sensory nerves. Importantly, mice injected with BC cells, in which the expression of the lactic acid transporter monocarboxylate transporter 4 (MCT4) was silenced, exhibited decreased BC‑BP with downregulated expression of pERK1/2 and pCREB in the DRG and reduced circulating levels of lactate compared with mice injected with parental BC cells. Further, silencing of the cell‑surface orphan receptor for lactate, G protein‑coupled receptor 81 (GPR81), in the F11 sensory neuron cells decreased lactate‑promoted upregulation of pERK1/2 and Ca²⁺ influx, suggesting that the sensory neuron excitation was inhibited. These results suggested that lactate released from BC cells via MCT4 induced BC‑BP through the activation of GPR81 of sensory neurons. In conclusion, the activation of GPR81 of sensory neurons by lactate released via MCT4 from BC was demonstrated to contribute to the induction of BC‑BP, and disruption of the interactions among lactate, MCT4 and GPR81 may be a novel approach to control BC‑BP.

Mouse Models of Tumor Bone Metastasis and Invasion for Studying CCN Proteins

Bone metastasis and bone destruction are common occurrences in human malignancies, including breast, prostate, and lung cancer, and are associated with a high morbidity rate because of intractable bone pain, pathological fractures, hypercalcemia, and nerve compression. Animal models of bone metastasis and bone destruction are important tools to investigate the pathogenesis and develop treatment strategies. However, there are few models of spontaneous bone metastasis despite the fact that animals often spontaneously develop cancer. Here, we describe methods for developing a mouse model of breast cancer bone metastasis achieved by injection of MDA-MB-231 breast cancer cells into the left cardiac ventricle. In addition, we introduce mouse model of the bone destruction by injection of SAS oral squamous cell carcinoma cells into the bone marrow space of the right tibial metaphysis. These assays can be applied to studies on roles of cellular communication network factor/connective tissue growth factor (CTGF/CCN2) protein in tumor metastasis and development of treatment strategies targeting CCN proteins.

[Surgical Treatment of Maxillary Gingival Carcinoma with Mental Retardation-A Case Report]

Many patients with mental retardation have a limited awareness of abnormalities in the oral cavity, making early detection of oral cancer difficult. Moreover, during examination and treatment, these patients may not understand well-intentioned verbal explanations and may express their anxiety through nonverbal communication. Herein we discuss a case in which favorable results were obtained when surgical treatment was performed on a maxillary gingival carcinoma patient with mental retardation. The patient was a 61-year-old man who was admitted to our hospital with maxillary gingival pain. A biopsy revealed well-differentiated oral squamous cell carcinoma(cT4aN0M0, Stage ⅣA). Hemi-maxillectomy was performed and postoperative recovery was uneventful. A maxillary prosthesis was provided for oral rehabilitation. At the 5-year follow-up, there were no signs of recurrence or metastasis. This case illustrates the importance of collaboration between oral maxillofacial surgeons and specialists from related departments for the comprehensive management of patients with mental retardation.

[A Case of Tongue Carcinoma with Malignant Transformation Caused by the Pandemic]

In April 2020, a state of emergency was declared because of the pandemic, and the public was instructed to refrain from leaving their homes. Consequently, this stirred up anxiety about visiting medical institutions. Here, we describe a case of tongue carcinoma that developed from an oral precancerous lesion into a malignant transformation owing to the effects of refraining from medical examinations caused by the pandemic. The patient was a 62-year-old woman. In March 2020, the patient became aware of a mass at the tongue's margin and was referred to our department. An excisional biopsy was performed, and a diagnosis of inflammatory change was made. The following month, a white ulcerative lesion was found, and another excisional biopsy was performed; therefore, a diagnosis of left tongue leukoplakia without epithelial dysplasia was made. The patient was scheduled for surgery; however, refused treatment and consultation because of the pandemic. In September 2021, the patient revisited our department on her own volition because an ulcerative lesion with indistinct borders and induration was found at the left lingual margin. Upon close examination, a diagnosis of left tongue squamous cell carcinoma(cT2N2bM0, Stage ⅣA)was made. In October 2021, radical tumor resection and reconstruction were performed. After 8 months postoperatively, the patient is currently well.

[Oral Function Restoration via Two-Stage Reconstructive Treatment of an Extensive Maxillary Defect Following Maxillectomy]

Recently, the number of survivors that had oral cancer has increased, but deterioration in the quality of life of patients concerning oral function and cosmetic appearance has become problematic. Prosthodontic dentures usefully treat jaw defects after maxillary resection for cancer, but advances in microsurgery have rendered the possibility to reconstruct maxillary defect and oral cavity using a microvascular flap. Here, we describe 2-stage treatment after 35 years postoperatively. We restored the maxillofacial function using microvascular flaps and partial denture. The patient was a 59-year-old woman who underwent left lateral maxillectomy 35 years previously to treat an advanced left maxilla gingival carcinoma. A maxillary prosthesis was applied, requiring repeated adjustments and refabrications. The patient visited to obtain improvements for oral and maxillofacial functions and long-term quality of life. The left maxillary bone defect was 45×50 mm in area. Collaborating with the Department of Plastic and Reconstructive Surgery, the patient underwent reconstructive treatment using a microvascular forearm flap and partial denture. The patient's progress was excellent; eating, swallowing, and articulation improved. For 1 year postoperatively, the patient was satisfied with the results.

[A Case of Lower Gingival Carcinoma Treated Surgically Using Computer-Assisted Patient-Specific Cutting Guide and Mandibular Reconstruction Plate]

We report a case of advanced lower gingival carcinoma treated with a computer-assisted custom-made surgical guide and reconstruction plate system(TruMatch®)in combination with a pectoralis major myocutaneous flap. In a 74-year-old male patient, a neoplastic lesion with a 30×30 mm periapical induration was observed around an extraction socket of left mandibular third molar. After various examinations, we diagnosed lower gingival carcinoma(cT4aN2bM0, Stage ⅣA). The patient was a paraplegic with a spinal cord injury, and reconstruction of mandible with free flap was not indicated, requiring minimally invasive surgery. Therefore, a surgical guide and reconstruction plate were prepared preoperatively using the Tru- Match® system. Under general anesthesia, the patient underwent tracheostomy, left modified radical neck dissection, segmental mandibulectomy, and reconstruction of the mandible using this system in combination with a pectoralis major myocutaneous flap. Postoperatively, the patient had minimal dysfunction. Currently, at 18 months follow up postoperatively, good prognosis was observed. In conclusion, this is a useful surgical system with accurate and less invasive surgery for segmental mandibulectomy of advanced lower gingival carcinoma.

Oral Dysfunction in Patients with Oral Cancer Could Occur Before Treatment and Require Early Nutritional Improvement: A Cross-Sectional Study

Patients with oral cancer have poor nutritional status before treatment. However, there have been no reports of the detailed evaluation of preoperative oral function in patients with oral squamous cell carcinoma (OSCC). Therefore, this study aimed to evaluate the preoperative oral function of patients with OSCC and examine the relationship with nutritional status. Oral function measurements (microorganisms, oral dryness, occlusal force, tongue pressure, masticatory function, Eating Assessment Tool, and Postoperative Oral Dysfunction Scale) and Mini Nutritional Assessment-Short Form (MNA-SF) data were collected from 51 patients with OSCC (men: 37, women: 14, mean age: 72.1 years) who visited the Shimane University Hospital, Department of Oral and Maxillofacial Surgery, from September 2019 to September 2021. The tongue was the most prevalent primary gingiva site [22 patients (43.1%)], and 36 patients (70.6%) had advanced cancer. Comparisons between nutritional status and each related factor revealed significant differences in the number of individuals in the household, cancer stage, presence of pulmonary disease, number of teeth, microorganisms (grade), and masticatory function (mg/dL) (p < 0.05). Multiple regression analysis using the total MNA-SF score as the dependent variable with adjustment for confounding factors showed significant association between oral dryness and tongue pressure (p < 0.05). No significant association was found for the Eating Assessment Tool or Postoperative Oral Dysfunction scale. Patients with OSCC may have decreased oral function because of the tumor at the time of diagnosis, which causes a decline in nutritional status. Preoperative interventions are necessary to improve nutrition based on the state of oral function.

Oral functional impairment may cause malnutrition following oral cancer treatment in a single-center cross-sectional study

Oral dysfunction and dysphagia after oral cancer treatment are linked to altered nutritional status. We aimed to identify specific oral functions related to nutritional status. We conducted a cross-sectional study from September 2019 to December 2021, recruited 75 participants (median age: 72.0 years), including 52 males and 23 females, collected background data, and evaluated oral function. The Mini Nutritional Assessment-Short Form (MNA-SF) scores were divided into three groups (normal nutritional status, at risk of malnutrition, and malnourished), and a multi-group comparison was conducted for each oral function measurement (microorganisms, oral dryness, occlusal force, tongue pressure, masticatory function, and Eating Assessment Tool [EAT-10]). The primary tumor site was the tongue in 31 patients (41.3%), gingiva in 30 (40.0%), and others in 14 (18.7%). Multiple comparisons revealed significant differences in occlusal force, tongue pressure, masticatory function, and EAT-10 levels, categorized as Type I (Transport type) and Type III (Occlusion type) postoperative oral dysfunctions, between each MNA-SF group. Multiple regression analysis showed a statistically significant association with MNA-SF in terms of masticatory function and EAT-10 levels, categorized as Type I. Type I and Type III are risk factors for malnutrition, confirming that different types of postoperative oral dysfunction require unique nutritional guidance.

Discrepancy between subjective and objective postoperative oral dysfunction assessment after oral cancer treatment: A single-center cross-sectional study

OBJECTIVES

It has been reported that in many cancer types, the evaluation of complications and side effects of treatment differs between subjective and objective evaluations. The purpose of this study is to verify whether the evaluation of postoperative oral dysfunction following oral cancer treatment was consistent subjective and objective evaluations.

MATERIALS AND METHODS

This cross-sectional study collected background data and evaluated the oral function (microorganisms, oral dryness, occlusal force, tongue pressure, masticatory function and eating assessment tool [EAT-10]) of 75 patients from September 2019 to December 2021. The postoperative oral dysfunction-10 (POD-10) was used for the subjective assessment of dysfunction in oral cancer patients. Also, Matsuda-Kanno classification was used for the objective assessment. The kappa coefficient between POD-10 and oral dysfunction was calculated for the degree of agreement. The relationship between oral function measurements and POD-10 was examined by multiple regression analysis.

RESULTS

The patients' median age was 72.0 (25-75 percentile: 64.0-78.0) and 69.3% were male. The kappa coefficients indicating the degree of agreement with POD-10 were 0.41 (P < 0.01) for occlusal force, 0.27 (P = 0.01) for masticatory function, and 0.59 (P < 0.01) for EAT-10. Multiple regression analysis showed a significant association of occlusal force (β = -0.33, P = 0.03) and EAT-10 (β = 0.80, P < 0.01) with POD-10.

CONCLUSIONS

For postoperative oral dysfunction type III (occlusal type), the evaluations of subjective and objective evaluations tended to be consistent. However, for type I (transport type) and II (oral hygiene type), these evaluations may be prone to overestimation or underestimation by either the medical professional or the patient.

Cutaneous branch of the nerve to the mylohyoid muscle: potential cause of postoperative sensory alteration in the submental area

BACKGROUND

Previous studies suggest that the nerve to the mylohyoid muscle could have a cutaneous branch. However, its clinical relevance has rarely been discussed because there is insufficient evidence for it. Our aim in this study was to investigate the anatomy of the cutaneous branch of the nerve to the mylohyoid muscle and extend the discussion to surgical management.

METHODS

Twenty sides from ten embalmed cadaveric heads were dissected to identify the cutaneous branch of the nerve to the mylohyoid muscle. The cutaneous branch was traced up to its termination.

RESULTS

The cutaneous branch was observed in 90% and classified into types I and II. In type I, the terminal trunk reached the anterior belly of the digastric muscle. In type II there were two types of terminal trunks, superior and inferior branches, which were identified on all sides. The number of the terminal trunk was one in 23.1% (type I; 6/26) and two in 76.9% (type II; 20/26).The terminal points of the cutaneous branch were all located within a 3cm×2cm rectangular segment in the center of the submental area.

CONCLUSIONS

We propose a new dermatome including the nerve to the mylohyoid muscle in the center. Understanding the cutaneous branch of the nerve could help surgeons to prevent iatrogenic sensory loss of the submental area.

Reproduction of the Antitumor Effect of Cisplatin and Cetuximab Using a Three-dimensional Spheroid Model in Oral Cancer

Background/Aim: Cancer research has been conducted using cultured cells as part of drug discovery testing, but conventional two-dimensional culture methods are unable to reflect the complex tumor microenvironment. On the other hand, three-dimensional cultures have recently been attracting attention as in vitro models that more closely resemble the in vivo physiological environment. The purpose of this study was to establish a 3D culture method for oral cancer and to verify its practicality. Materials and Methods: Three-dimensional cultures were performed using several oral cancer cell lines. Western blotting was used for protein expression analysis of the collected cell masses (spheroids), and H-E staining was used for structural observation. The cultures were exposed to cisplatin and cetuximab and the morphological changes of spheroids over time and the expression changes of target proteins were compared. Results: Each cell line formed spheroidal cell aggregates and showed enhancement of cell adhesion molecules over time. H-E staining showed tumor tissue-like structures specific to each cell line. Cisplatin showed concentration-dependent antitumor effects due to loss of cell adhesion and spheroid disruption in each cell line, while cetuximab exhibited antitumor effects that correlated with EGFR expression in each cell line. Conclusion: Spheroids made from oral cancer cell lines appeared to have tumor-like characteristics that may reflect their clinical significance. In the future, it may become possible to produce tumor spheroids from tissue samples of oral cancer patients, and then apply them to drug screening and to develop individualized diagnostic and treatment methods.

A Narrative Review of u-HA/PLLA, a Bioactive Resorbable Reconstruction Material: Applications in Oral and Maxillofacial Surgery

The advent of bioresorbable materials to overcome limitations and replace traditional bone-reconstruction titanium-plate systems for bone fixation, thus achieving greater efficiency and safety in medical and dental applications, has ushered in a new era in biomaterial development. Because of its bioactive osteoconductive ability and biocompatibility, the forged composite of uncalcined/unsintered hydroxyapatite and poly L-lactic acid (u-HA/PLLA) has attracted considerable interest from researchers in bone tissue engineering, as well as from clinicians, particularly for applications in maxillofacial reconstructive surgery. Thus, various in vitro studies, in vivo studies, and clinical trials have been conducted to investigate the feasibility and weaknesses of this biomaterial in oral and maxillofacial surgery. Various technical improvements have been proposed to optimize its advantages and limit its disadvantages. This narrative review presents an up-to-date, comprehensive review of u-HA/PLLA, a bioactive osteoconductive and bioresorbable bone-reconstruction and -fixation material, in the context of oral and maxillofacial surgery, notably maxillofacial trauma, orthognathic surgery, and maxillofacial reconstruction. It simultaneously introduces new trends in the development of bioresorbable materials that could used in this field. Various studies have shown the superiority of u-HA/PLLA, a third-generation bioresorbable biomaterial with high mechanical strength, biocompatibility, and bioactive osteoconductivity, compared to other bioresorbable materials. Future developments may focus on controlling its bioactivity and biodegradation rate and enhancing its mechanical strength.

[A Case of Polymorphous Low-Grade Adenocarcinoma of the Palate]

Polymorphous low-grade adenocarcinoma(PLGA)is a relatively rare low-grade adenocarcinoma of the minor salivary glands. If radical resection is performed, the prognosis is favorable. We present the case of a 62-year-old woman who presented to our clinic in April 2019 after noticing a mass on her palate. The intraoral examination revealed a 10-mm-diameter, well-defined, tender mass extending from the right hard palate to the soft palate. We suspected a benign tumor originating from the area of transition between the hard and soft palates. An excisional biopsy of the mass was performed, and PLGA was diagnosed on the basis of histopathologic findings. In May 2019, the tumor was resected under general anesthesia and a soft palatal lift prosthesis was applied for functional recovery. In July 2020, the soft palate defect was repaired using an ulnar forearm free flap during a two-stage reconstruction procedure. The patient developed complete necrosis of the free flap, and the defect was re-reconstructed using a buccinator-based myomucosal flap. There was no evidence of disease recurrence or metastasis. Two years have passed since the initial surgery, and the patient's clinical course has been well so far.

[Mass Screening of Oral Cancer in Eastern Shimane Prefecture during 2015-2019]

The Department of Oral and Maxillofacial Surgery, Shimane University Faculty of Medicine, has been conducting mass screening of oral cancer using oral abrasion cytology by oral surgeons in eastern Shimane prefecture for public awareness and its early detection. As a result, 3(0.09%)cases of oral cancer were identified. Case 1: The patient was diagnosed with well-differentiated squamous cell carcinoma in the floor of the mouth(pT1N0M0, Stage Ⅰ)after undergoing Matsue city oral cancer screening in 2016. Case 2: The patient underwent oral cancer screening in Izumo city in 2018 and was diagnosed with verrucous carcinoma in the back of the tongue(pT1N0M0, Stage Ⅰ). Case 3: The patient was diagnosed with highly differentiated squamous cell carcinoma of the palate(pT1N0M0, Stage Ⅰ)after undergoing the Izumo city oral cancer screening in 2019. Awareness of oral cancer is important, and cancer screening by oral surgeons using cytology is highly useful and should be continued in the future.

[A Case of Treatment Applicable to Squamous Cell Carcinoma of the Tongue by Mass Screening Examination of Oral Cancer in Western Part of the Shimane Prefecture]

Radical excision, a common oral cancer treatment, produces variable postoperative results depending on the specialized tissues involved and the extent of the cancer. Furthermore, the material selected for reconstruction also influences functional outcomes. Oral dysfunction due to postoperative tissue loss is more common with advanced cancer; therefore, early detection and treatment are important. To improve oral cancer awareness and early detection, mass oral cancer screenings led by maxillofacial surgeons in cooperation with the Shimane prefecture and local dental associations were conducted. We describe the mass screening methods and describe a case of tongue cancer that was detected and treated as a result of our screening efforts.

[A Clinical Study of Orofacial Defect Reconstruction Using a Modified Submental Island Flap following Oral Cancer Resection]

INTRODUCTION

Pedicled flaps are used in orofacial defect reconstruction in older patients and patients with underlying diseases. The submental island flap(SIF)is one type of cervical pedicled flap; however, the modified submental island flap (MSIF), which includes mylohyoid muscle, is a simpler and safer type. Here, we report a clinical study of orofacial defect reconstruction using the MSIF following oral cancer resection.

PATIENTS AND METHODS

From January 2019 to December 2020, we retrospectively examined 10 cases of reconstruction using the MSIF following oral squamous cell carcinoma resection.

RESULTS

The study population consisted of 7 men and 3 women with a mean age of 76.0(66-88)years. The primary sites were lower gingiva(n=5), tongue(n=3), and buccal mucosa in(n=2). Surgical procedures included marginal mandibulectomy( n=3), segmental mandibulectomy(n=1), partial glossectomy(n=2), hemiglossectomy(n=1), buccal mucosa resection(n=2), and combined partial glossectomy and segmental mandibulectomy(n=1). The average flap size was 61.4×36.0 mm. The average time of flap elevation was 32.4(23-50)minutes. During orofacial surgery using the MSIF, organs adjacent to the primary site could also be reconstructed. There were no complications in any patients.

CONCLUSION

The MSIF is useful for orofacial defect reconstruction in older patients and patients with underlying diseases.

[Functional Recovery following Incisional Cheiloplasty for Lower Labial Edema That Developed after Bilateral Neck Dissection and Postoperative Chemoradiotherapy-A Case Report]

We report a case of functional recovery following incisional cheiloplasty for the management of lower labial edema that developed after bilateral neck dissection with preservation of the one-side internal jugular vein and postoperative chemoradiotherapy. An 81-year-old woman underwent partial maxillectomy for the treatment of maxillary gingival cancer(squamous cell carcinoma, cT1N0M0, Stage Ⅰ)in April 2013. In July 2013, she underwent bilateral neck dissection(right, modified; left, radical)for bilateral cervical lymph node recurrence with an extra-nodal spread and received postoperative chemoradiotherapy( CDDP 75 mg/m2×3 course and total radiotherapy dosage of 66 Gy). Thereafter, the patient's condition progressed without recurrence or metastasis; however, the lower labium became edematous, and severe labial dysfunction was observed. Therefore, lower labial incisional cheiloplasty was performed under local anesthesia in October 2020. An excision area of 160×14 mm was determined on the inner side of the lower labium, and excision was performed with a steel blade scalpel. Lip closure became possible one week after the operation. Seven months after the operation, the patient recovered labial function and was satisfied with the outcome.

[A Case of Recurrent Squamous Cell Carcinoma of the Mandibular Gingiva Around a Mandibular Dental Implant]

Extensive bimaxillary bone support devices(hereafter referred to as a dental implant)are useful for morphological and functional reconstruction after resection of oral cancer. However, tumor recurrence due to peri-implantitis may occur. In this report, we describe a case of squamous cell carcinoma(SqCC)recurrence around a mandibular dental implant. An 80-year- old female patient underwent tumor resection and stratification for SqCC extending from the left lingual margin to the gingiva of the left lower molar in 2013. In 2014, 2 dental implants were placed in the bilateral mandibular canine region and a prosthetic device of implant-overdenture was installed. Six years after the primary tumor resection, a mass lesion was found in the peri-implant area of the left mandibular canine. Upon examination, the patient was diagnosed with SqCC recurrence and underwent radical tumor resection and immediate reconstruction using a submental flap and a reconstruction plate. Additional dental implants were concurrently placed in the remaining mandible. There was no evidence of recurrence, and the patient remains under careful observation so far.

The Epithelial-Mesenchymal Transition Influences the Resistance of Oral Squamous Cell Carcinoma to Monoclonal Antibodies via Its Effect on Energy Homeostasis and the Tumor Microenvironment

Oral squamous cell carcinoma (OSCC) is a major type of cancer that accounts for over 90% of all oral cancer cases. Recently developed evidence-based therapeutic regimens for OSCC based on monoclonal antibodies (mAbs), such as cetuximab, pembrolizumab, and nivolumab, have attracted considerable attention worldwide due to their high specificity, low toxicity, and low rates of intolerance. However, the efficacy of those three mAbs remains poor because of the low rate of responders and acquired resistance within a short period of time. The epithelial-mesenchymal transition (EMT) process is fundamental for OSCC growth and metastasis and is also responsible for the poor response to mAbs. During EMT, cancer cells consume abundant energy substrates and create an immunosuppressive tumor microenvironment to support their growth and evade T cells. In this review, we provide an overview of the complex roles of major substrates and signaling pathways involved in the development of therapeutic resistance in OSCC. In addition, we summarize potential therapeutic strategies that may help overcome this resistance. This review aims to help oral oncologists and researchers aiming to manage OSCC and establish new treatment modalities.

An anatomical study of the blood supply to the mylohyoid muscle: the so-called "mylohyoid branch" of the inferior alveolar artery is an arterial anastomosis

BACKGROUND

The aim of this study was to clarify the morphology of the mylohyoid branch of the inferior alveolar artery and the main blood supply to the mylohyoid muscle.

METHODS

The maxillary artery (MA) and inferior alveolar artery (IAA) within the infratemporal fossa, the facial and submental arteries within the submandibular triangle, and the nerve to the mylohyoid muscle and related artery were dissected in twelve sides from embalmed cadaveric heads. The main blood supply to the extraoral (inferior) surface of the mylohyoid muscle was recorded.

RESULTS

The mylohyoid branch of the inferior alveolar artery was an anastomosis of the descending branch of either the inferior alveolar or maxillary artery and the ascending branch of either the submental or facial artery. The anastomosis was classified into four types according to the origins of the arteries. The main blood supply to the extraoral surface of the mylohyoid muscle was the submental artery.

CONCLUSIONS

The results of this study indicate that the mylohyoid branch of the IAA in human adults is an anastomosis of branches of the maxillary and facial arteries.

Development of a Subjective Symptom Rating Scale for Postoperative Oral Dysfunction in Patients with Oral Cancer: Reliability and Validity of the Postoperative Oral Dysfunction Scale-10

Currently, there is no scale to subjectively assess postoperative oral dysfunction in patients with oral cancer. The purpose of this study was to evaluate the reliability and validity of the Postoperative Oral Dysfunction Scale (POD-10) that we developed. Between September 2019 and August 2021, 62 eligible oral cancer patients (median age, 72 years; 42 men and 20 women) were enrolled in the study. The Cronbach’s alpha coefficient, which indicates the internal consistency of the scale, was 0.94, and the intraclass correlation coefficient, which indicates reproducibility, was 0.85 (95% confidential interval: 0.40–0.96, p < 0.05). Concurrent validity testing showed a statistically significant correlation between POD-10 and Eating Assessment Tool (EAT-10) (r = 0.89, p < 0.05). To test discriminant validity, statistically significant differences were found between early-stage cancer (stage I and II) and advanced-stage cancer (stage III and IV) (p < 0.05). Twenty-four points were calculated as the cutoff value for POD-10 using receiver operating characteristic analysis to calculate the cutoff value. The POD-10 was shown to be a clinically reliable and valid scale that can be used to subjectively assess postoperative oral dysfunction in patients with oral cancer and is expected to be used as a simple diagnostic tool.

Dynamic contrast-enhanced MRI as a predictor of programmed death ligand-1 expression in patients with oral squamous cell carcinoma

Immune checkpoint inhibitors (ICIs) targeting programmed death ligand-1 (PD-L1) are highly promising therapies for oral squamous cell carcinoma (OSCC). The assessment of PD-L1 expression may help predicting the therapeutic effect of ICIs and, thus, benefit patient selection. Contrast index (CI) parameters derived from dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) have been proven as efficient to assess microvessel density (MVD) in OSCC. The present study aimed to determine the correlation between DCE-MRI parameters and MVD and between DCE-MRI parameters and PD-L1 expression to determine whether DCE-MRI could be used non-invasively to evaluate PD-L1 expression in patients with OSCC. A total of 21 patients with primary OSCC who had undergone a 3T MRI scan, including DCE-MRI, were included in the present study, and CI curve-derived parameters were examined. The MVD and PD-L1 expression in the surgically resected specimens were analyzed using immunohistochemistry (IHC) staining for CD31 and IHC staining for PD-L1, respectively. The results demonstrated that the expression levels of these markers were correlated with DCE-MRI parameters. PD-L1 expression levels were found to be significantly correlated with the maximum CI (CI-max; P=0.007), peak CI (CI-peak; P=0.007), maximum CI gain (CI-gain; P=0.006) and MVD (P=0.001) values. The mean CI-max, CI-peak, CI-gain and MVD values were significantly higher in tumors with high PD-L1 expression (P<0.05). MVD levels were also significantly correlated with the time of CI-max (T-max; P=0.003) and CI-gain (P=0.037). The mean CI-gain was significantly increased, and the mean T-max was significantly shorter in high MVD tumors (P<0.05 and P<0.01, respectively). In summary, the findings from the present study confirmed the correlation between CI parameters, derived from DCE-MRI, and MVD, and suggested that these parameters may be correlated with PD-L1 expression in OSCC tumor cells.

Sensory nerves: A driver of the vicious cycle in bone metastasis?

Bone is one of the preferential target organs of cancer metastasis. Bone metastasis is associated with various complications, of which bone pain is most common and debilitating. The cancer-associated bone pain (CABP) is induced as a consequence of increased neurogenesis, reprogramming and axonogenesis of sensory nerves (SNs) in harmony with sensitization and excitation of SNs in response to the tumor microenvironment created in bone. Importantly, CABP is associated with increased mortality, of which precise cellular and molecular mechanism remains poorly understood. Bone is densely innervated by autonomic nerves (ANs) (sympathetic and parasympathetic nerves) and SNs. Recent studies have shown that the nerves innervating the tumor microenvironment establish intimate communications with tumors, producing various stimuli for tumors to progress and disseminate. In this review, our current understanding of the role of SNs innervating bone in the pathophysiology of CABP will be overviewed. Then the hypothesis that SNs facilitate cancer progression in bone will be discussed in conjunction with our recent findings that SNs play an important role not only in the induction of CABP but also the progression of bone metastasis using a preclinical model of CABP. It is suggested that SNs are a critical component of the bone microenvironment that drives the vicious cycle between bone and cancer to progress bone metastasis. Suppression of the activity of bone-innervating SNs may have potential therapeutic effects on the progression of bone metastasis and induction of CABP.

Postoperative oral dysfunction following oral cancer resection and reconstruction: A preliminary cross-sectional study

OBJECTIVES

Oral cancer treatment reportedly causes decreased oral function, but few studies have examined the effects of oral cancer treatment on oral function in depth. This study aimed to comprehensively evaluate the oral function after treatment and classify the conditions related to oral dysfunction in patients with oral cancer.

MATERIALS AND METHODS

We recruited participants, collected their background data, and evaluated their oral function from September 2019 to March 2021. Principal component analysis was used to identify the components of oral function measurement and oral health perception. Receiver operating characteristic analysis was performed to investigate the accuracy of oral function measurements in predicting oral intake and nutritional status.

RESULTS

Fifty patients treated for oral cancer, including 33 (66.0%) males and 17 (34.0%) females, were included. Their median age was 71.0 years (interquartile range: 63.0-76.0). There were significant differences in oral dryness between males and females, occlusal force among different age groups, tongue pressure based on the tumor stage and performance of reconstructive procedures, and masticatory function and Eating Assessment Tool scores based on whether radiotherapy was performed (P < 0.05). The principal component analysis proposed that oral function measurements and subjective oral health perception could be divided into three main components (transport, oral hygiene, and occlusion type), which explain 61.5% of the variance of the phenomenon.

CONCLUSION

A significant decrease in oral function after oral cancer treatment should be diagnosed as postoperative oral dysfunction. Postoperative oral dysfunction can be classified into three types, each of which may present with different pathologies.

A case of langerhans cell histiocytosis of the mandible that spontaneously regressed after biopsy in a child

In younger patients of LCH, we should consider that the effectiveness of follow-up without aggressive treatment for SS-type LCH in the oral and maxillofacial bone. However, there are very rare case in which an SS-type LCH recurred after showing a healing tendency. Regular follow-up must be performed even after healing.

Bioactive Regeneration Potential of the Newly Developed Uncalcined/Unsintered Hydroxyapatite and Poly-l-Lactide-Co-Glycolide Biomaterial in Maxillofacial Reconstructive Surgery: An In Vivo Preliminary Study

Uncalcined/unsintered hydroxyapatite (HA) and poly-l-lactide-co-glycolide (u-HA/PLLA/PGA) are novel bioresorbable bioactive materials with bone regeneration characteristics and have been used to treat mandibular defects in a rat model. However, the bone regenerative interaction with the periosteum, the inflammatory response, and the degradation of this material have not been examined. In this study, we used a rat mandible model to compare the above features in u-HA/PLLA/PGA and uncalcined/unsintered HA and poly-l-lactic acid (u-HA/PLLA). We divided 11 male Sprague–Dawley rats into 3- and 16-week groups. In each group, we assessed the characteristics of a u-HA/PLLA/PGA sheet covering the right mandibular angle and a u-HA/PLLA sheet covering the left mandibular angle in three rats each, and one rat was used as a sham control. The remaining three rats in the 16-week group were used for a degradation assessment and received both sheets of material as in the material assessment subgroup. At 3 and 16 weeks after surgery, the rats were sacrificed, and mandible specimens were subjected to micro-computed tomography, histological analysis, and immunohistochemical staining. The results indicated that the interaction between the periosteum and u-HA/PLLA/PGA material produced significantly more new bone regeneration with a lower inflammatory response and a faster resorption rate compared to u-HA/PLLA alone. These findings may indicate that this new biomaterial has ideal potential in treating maxillofacial defects of the midface and orbital regions.

A case of intramandibular neurofibroma resembling a radicular cyst in a neurofibromatosis type 1 patient

INTRODUCTION

Neurofibromatosis is a disease that causes various abnormalities such as neurofibroma, mainly in the skin and nerves. The common sites in the oral cavity are the palate, gingiva, tongue, buccal mucosa, and lips but, occurrence in the mandible is rare.

PRESENTATION OF CASE

A 26-year-old woman was referred to our clinic because of percussion pain. Radiographic findings showed a radiolucent area. The patient was clinically diagnosed with a radicular cyst by a previous doctor. Multiple café-au-lait spots were found disseminated on her body, and she had already been prenatally diagnosed with neurofibromatosis type 1 (NF1). We performed a biopsy and suggested a neurofibroma. Tumor extirpation was performed under general anesthesia. The histopathological diagnosis showed a neurofibroma.

CLINICAL DISCUSSION AND CONCLUSION

NF1 is a systemic nevus that causes abnormalities in melanocytes and Schwann cells, and various lesions appear, but intramandibular lesions are extremely rare. Diagnosis of NF1 and radicular cysts in the mandible is difficult due to their image resemblance. However, it should be kept in mind if the underlying disease is NF1. In our case, it was easy to detach and may have originated from small peripheral nerve endings in the mandible.

Complications of Poly-l-Lactic Acid and Polyglycolic Acid (PLLA/PGA) Osteosynthesis Systems for Maxillofacial Surgery: A Retrospective Clinical Investigation

Two second-generation PLLA/PGA bioresorbable osteosynthetic plate systems for oral and maxillofacial surgery are available in Japan. The two systems have different PLLA-PGA component ratios (RapidSorb^®, 85:15; Lactosorb^®, 82:18) and plate and screw shapes. We conducted a retrospective study to compare our clinical evaluation and examine the incidence of postoperative complications between the two plate systems. A retrospective survey was conducted in 148 patients (midfacial fracture/trauma (68.2%) and dentofacial deformity patients (31.8%); males (54.7%); median age, 37.5 years) treated using maxillofacial osteosynthetic plate systems. The complications included plate exposure (7.4%), infection, (2.7%), and plate breakage (0.7%). Multivariate logistic regression analysis showed a significant correlation between sex (female), plate system (Lactosorb^®), number of plates, and pyriform aperture and periorbital sites of plate placement (p < 0.05). Additionally, the propensity score-adjusted model showed a significant correlation between Lactosorb^® and postoperative complications (odds ratio 1.007 (95% confidence interval, 1.001–1.055), p < 0.01). However, the two plate systems showed a low incidence rate of complications, and the plate integration and survivability were similar using 2.0-mm or 1.5-mm resorbable plate regardless of the plate system. Our findings suggest that female sex and a greater number of plates are risk factors for postoperative complications, whereas pyriform aperture and periorbital plate placements reduce the risk.

Expression of SARS-CoV-2 entry factors in human oral tissue

The distribution of cells expressing SARS‐CoV‐2 entry factor angiotensin‐converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2) in human oral tissues were tested. The investigation was conducted with normal flesh tissue and paraffin‐embedded specimens. The ACE2 and TMPRSS2 expression was detected with all subjects in the normal mucosa of the keratinized stratified squamous epithelia of the tongue and non‐keratinized stratified squamous epithelia of the lip and cheek. It was found that ACE2 is expressed in the cytoplasm and on the cell membrane mainly in the stratum granulosum of the epithelia while the TMPRSS2 is strongly expressed on the cell membrane mainly in the stratum granulosum and stratum spinosum, but not in the stratum basale. Antibodies’ reactions for ACE2 and TMPRSS2 were not observed in the nuclei or keratin layer. The expression of ACE2 and TMPRSS2 in the oral epithelia appears to be general, and the expression was also observed in the mucous and serous acini of the labial glands. The SARS‐CoV‐2 may transiently attach to the oral mucosa and the minor salivary glands which are present under all of the oral mucosa. The oral cavity can be considered an important organ for SARS‐CoV‐2 attachment and may provide a preventive medical avenue to guard against COVID‐19 by preventing saliva from scattering.

Surgical resection of a giant peripheral ossifying fibroma in mouth floor managed with fiberscopic intubation

Tracheal intubation for general anesthesia can sometimes be difficult in patients with a large mass in the mouth floor. Preoperative evaluation of the patient's airway is most important when treating large oral disease.

Dual innervation of the submandibular gland by nerve to mylohyoid and chorda tympani

The chorda tympani typically utilises the lingual nerve and submandibular ganglion to transmit parasympathetic fibres to the submandibular gland. During a routine anatomy dissection, the submandibular gland was found to be innervated by both the lingual nerve and the nerve to mylohyoid. The clinical implications of this variant dual innervation to the submandibular gland is not clear due to its rarity: however, recognising such a variation should be borne in mind during surgical intervention near the nerve to mylohyoid.

A case of oral cancer with delayed occipital lymph node metastasis: Case report

Consideration of unexpected metastasis in patients who have undergone neck dissection with advanced tumors must be anticipated with careful follow-up.

Rab11A Functions as a Negative Regulator of Osteoclastogenesis through Dictating Lysosome-Induced Proteolysis of c-fms and RANK Surface Receptors

Osteoclast differentiation and activity are controlled by two essential cytokines, macrophage colony-stimulating factor (M-CSF) and the receptor activator of nuclear factor-κB ligand (RANKL). Rab11A GTPase, belonging to Rab11 subfamily representing the largest branch of Ras superfamily of small GTPases, has been identified as one of the crucial regulators of cell surface receptor recycling. Nevertheless, the regulatory role of Rab11A in osteoclast differentiation has been completely unknown. In this study, we found that Rab11A was strongly upregulated at a late stage of osteoclast differentiation derived from bone marrow-derived macrophages (BMMs) or RAW-D murine osteoclast precursor cells. Rab11A silencing promoted osteoclast formation and significantly increased the surface levels of c-fms and receptor activator of nuclear factor-κB (RANK) while its overexpression attenuated osteoclast formation and the surface levels of c-fms and RANK. Using immunocytochemical staining for tracking Rab11A vesicular localization, we observed that Rab11A was localized in early and late endosomes, but not lysosomes. Intriguingly, Rab11A overexpression caused the enhancement of fluorescent intensity and size-based enlargement of early endosomes. Besides, Rab11A overexpression promoted lysosomal activity via elevating the endogenous levels of a specific lysosomal protein, LAMP1, and two key lysosomal enzymes, cathepsins B and D in osteoclasts. More importantly, inhibition of the lysosomal activity by chloroquine, we found that the endogenous levels of c-fms and RANK proteins were enhanced in osteoclasts. From these observations, we suggest a novel function of Rab11A as a negative regulator of osteoclastogenesis mainly through (i) abolishing the surface abundance of c-fms and RANK receptors, and (ii) upregulating lysosomal activity, subsequently augmenting the degradation of c-fms and RANK receptors, probably via the axis of early endosomes-late endosomes-lysosomes in osteoclasts.

The HMGB1/RAGE axis induces bone pain associated with colonization of 4T1 mouse breast cancer in bone

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The 4T1 mouse breast cancer injected in tibiae induced bone pain.

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The 4T1 breast cancer secreted high mobility group box 1 (HMGB1) that promotes axogenesis of sensory neurons.

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Bone pain was reduced by HMGB1 antibody and an antagonist for the receptor for advanced glycation end products.

Bone pain is a common complication of breast cancer (BC) bone metastasis and is a major cause of increased morbidity and mortality. Although the mechanism of BC-associated bone pain (BCABP) remains poorly understood, involvement of BC products in the pathophysiology of BCABP has been proposed. Aggressive cancers secrete damage-associated molecular patterns (DAMPs) that bind to specific DAMP receptors and modulate cancer microenvironment. A prototypic DAMP, high mobility group box 1 (HMGB1), which acts as a ligand for the receptor for advanced glycation end products (RAGE) and toll-like receptors (TLRs), is increased in its expression in BC patients with poor outcomes. Here we show that 4T1 mouse BC cells colonizing bone up-regulate the expression of molecular pain markers, phosphorylated ERK1/2 (pERK) and pCREB, in the dorsal root ganglia (DRGs) innervating bone and induced BCABP as evaluated by hind-paw mechanical hypersensitivity. Importantly, silencing HMGB1 in 4T1 BC cells by shRNA reduced pERK and pCREB and BCABP with decreased HMGB1 levels in bone. Further, administration of a neutralizing antibody to HMGB1 or an antagonist for RAGE, FPS-ZM1, ameliorated pERK, pCREB and BCABP, while a TLR4 antagonist, TAK242, showed no effects. Consistent with these in vivo results, co-cultures of F11 sensory neuron-like cells with 4T1 BC cells in microfluidic culture platforms increased neurite outgrowth of F11 cells, which was blocked by HMGB1 antibody. Our results show that HMGB1 secreted by BC cells induces BCABP via binding to RAGE of sensory neurons and suggest that the HMGB1/RAGE axis may be a potential novel therapeutic target for BCABP.