Clinicopathological characteristics of four major histological types of high-grade parotid carcinoma.

OBJECTIVE: High-grade parotid carcinoma generally has a poor prognosis, and the histological type is mucoepidermoid carcinoma (MEC), salivary duct carcinoma (SDC), carcinoma ex pleomorphic adenoma (CEPA), or adenoid cystic carcinoma (AdCC) in the majority of cases. METHODS: During the 23-year period from September 1999 to December 2022, 250 patients with parotid carcinoma underwent initial treatment and had the histopathological type of their carcinoma. Retrospective study evaluated 111 MEC, SDC, CEPA, or AdCC cases among 134 patients with high-grade parotid carcinoma. We examined pathological and clinical features and prognosis, evaluated factors associated with recurrence, and performed immunohistological examinations. RESULTS: Pathological and clinical features and factors associated with recurrence were different for each histological type. The 10-year disease-free survival rates were as follows: MEC, 34.9%; SDC, 22.6%; CEPA, 47.1%; and AdCC, 56.3%. Human epidermal growth factor receptor type-2 and androgen receptor were positive in 48% and 56% of patients with SDC, respectively, 38% and 25% of those with CEPA. CONCLUSION: Each histological type has its own pathological and clinical features, recurrence types, and tumor activities, suggesting that differentiating between high-grade parotid carcinomas according to histological type will improve diagnosis, and thus prognosis.

Predicting postoperative facial nerve paralysis by using intraoperative nerve monitoring during parotid surgery.

OBJECTIVES: To investigate a method for predicting postoperative facial nerve paralysis (POFNP) during parotid surgery using intraoperative nerve monitoring (IONM). METHODS: We assessed prediction for POFNP by using IONM, comparing between stimulation in the facial nerve trunk and each branch by using facial nerve monitoring. The amplitude response ratio (ARR) was calculated for the trunk/periphery. In addition, we then examined the correlation between ARR and time to recovery of paralyzed branches. RESULTS: 372 branches of 93 patients did not develop POFNP and were classified as group A. Among 20 patients who developed POFNP, 51 branches without POFNP were classified as group B, and 29 branches with POFNP were classified as group C. The ARR was approximately 1 in group A and B. but less than 0.5 in all branches in Group C. When the cut off value of ARR was set at 0.55, the sensitivity, specificity, and accuracy of POFNP diagnosis by ARR were 96.5%, 93.1%, and 96.8%, respectively. CONCLUSION: Using IONM during parotid surgery enables easy prediction of POFNP.

Increased Chymase-Positive Mast Cells in High-Grade Mucoepidermoid Carcinoma of the Parotid Gland.

It has long been known that high-grade mucoepidermoid carcinoma (MEC) has a poor prognosis, but the detailed molecular and biological mechanisms underlying this are not fully understood. In the present study, the pattern of chymase-positive mast cells, as well as chymase gene expression, in high-grade MEC was compared to that of low-grade and intermediate-grade MEC by using 44 resected tumor samples of MEC of the parotid gland. Chymase expression, as well as chymase-positive mast cells, was found to be markedly increased in high-grade MEC. Significant increases in PCNA-positive cells and VEGF gene expression, as well as lymphangiogenesis, were also confirmed in high-grade MEC. Chymase substrates, such as the latent transforming growth factor-beta (TGF-ß) 1 and pro-matrix metalloproteinase (MMP)-9, were also detected immunohistologically in high-grade MEC. These findings suggested that the increased chymase activity may increase proliferative activity, as well as metastasis in the malignant condition, and the inhibition of chymase may be a strategy to improve the poor prognosis of high-grade MEC of the parotid gland.

Executive summary: Japanese guidelines for allergic rhinitis 2020.

The Practical Guideline for the Management of Allergic Rhinitis, the fist guideline for allergic rhinitis in Japan, was prepared after a symposium held by the Japanese Society of Allergology in 1993. The current 9th edition was published in 2020 and is widely used today. The most recent collection of evidence from the literature was supplemented to the revised guideline to incorporate evidence-based medicine. The revised guideline includes updated epidemiology of allergic rhinitis in Japan, a figure representing the mechanisms of allergic rhinitis in both the onset and sensitization phases with the introduction of regulatory T cells and type 2 innate lymphoid cells, practical assessment for diagnosis, new pharmacotherapy agents such as anti-IgE mAb and a new drug delivery system for antihistamines, sublingual immunotherapy for children, dual sublingual immunotherapy for house dust mites and Japanese cedar pollen extract, new classification for surgery for allergic rhinitis, and treatment and prescriptions for older adults. An evidence-based step-by-step strategy for treatment is also described.

Sublingual immunotherapy for 4 years increased the number of Foxp3+ Treg cells, which correlated with clinical effects.

OBJECTIVE: At least 3 years of sublingual immunotherapy (SLIT) is required to achieve long-term clinical tolerance for allergens. However, immunological changes with more than 3 years of SLIT have not yet been elucidated in detail. The present study investigated whether the numbers of regulatory T (Treg) cells and regulatory B (Breg) cells increased with 4 years of SLIT and if these increases correlated with clinical effects for pollinosis. METHODS: Seven Japanese cedar pollinosis patients received SLIT in 2014 or 2015 and continued treatment until May 2019. In May 2017 and May 2019, peripheral blood mononuclear cells (PBMCs) were collected from the patients, and analyzed by flow cytometer. RESULTS: (1) The visual analogue scale (VAS) was significantly higher in 2019 than in 2017. (2) The percentages of Foxp3+ Treg cells, type 1 regulatory T (Tr1) cells, and Breg cells in PBMCs were significantly higher in 2019 than in 2017. (3) The percentage of Foxp3+ Treg cells in PBMCs positively correlated with VAS, whereas those of Tr1 cells and Breg cells did not. CONCLUSIONS: These results suggest that 4 years of SLIT is needed to achieve sustained increases in Foxp3+ Treg cells, which are closely associated with the efficacy of SLIT.

Symptoms and signs of parotid tumors and their value for diagnosis and prognosis: a 20-year review at a single institution.

BACKGROUND: Detailed clinical features other than parotid mass have not been investigated in detail for parotid tumors. Symptoms and signs are useful for the differentiation of benign versus malignant, and may also be of value to determine the grade of malignancy and histological type as well as the assessment of prognosis. METHODS: We reviewed symptoms and signs of 965 patients with benign tumors and 200 patients with malignant tumors. Symptoms and signs included pain/tenderness, adhesion to surrounding tissues, and facial nerve palsy. We reviewed the incidence in benign and malignant tumors, in histological type of benign tumors, and in grade and histology of malignant tumors. For each symptom or sign, covariates were analyzed, and their correlation with the prognosis was investigated. RESULTS: The incidence of symptoms and signs was significantly higher in malignant than benign tumors, and more frequent in higher grade of malignancy. Facial nerve palsy was observed in 18.0% of malignant tumor cases, while none occurred in benign tumor cases. Pain/tenderness was more commonly observed in adenoid cystic carcinoma, while adhesion to surrounding tissues and facial nerve palsy were most frequently noted in salivary duct carcinoma. The prognosis of patients with these symptoms and signs was significantly poor. CONCLUSION: A detailed investigation of symptoms and signs in parotid gland tumors is the first step that leads to the diagnosis of malignant tumors. Symptoms and signs are also useful for estimating the grade of malignancy and histological type, and they are important information for predicting prognosis.

A novel clinically-oriented classification of fine-needle aspiration cytology for salivary gland tumors: a 20-year retrospective analysis of 1175 patients.

BACKGROUND: When determining treatment strategy for a salivary gland tumor, assessing histology and malignancy grade before surgery is essential. Several new diagnostic classification systems for salivary gland cytology have recently been proposed. However, none incorporate histology and grade of malignancy. METHODS: We developed a new cytology classification system that incorporates histology and grade of malignancy of salivary gland tumors (OMC classification), consisting of 11 categories. Our OMC classification was applied to 1175 patients who had preoperative cytology and confirmed final pathological diagnosis available from the past 20 years at our hospital (benign tumor: 981 patients, malignant tumor: 194 patients). RESULTS: Based on the cytology, 729 patients (62.0%) had benign histology (Category 4-1), and 87 patients (7.4%) were diagnosed with grade of malignancy (Category 6-3 + 6-4). Based on the final pathological diagnosis, the accuracy rate of Category 4-1 and Category 6-3 + 6-4 of our classification system was 93.4% and 88.5%, respectively. CONCLUSION: Based on the correct diagnosis rate, the inclusion of histology and grade of malignancy in the salivary gland cytology classification was considered feasible. Thus, the OMC classification system is considered a useful tool when determining the treatment strategy for a salivary gland tumor.

Effective surgical management of anterior tumors of the parotid gland: Main trunk method vs. peripheral Smethod.

OBJECTIVE: Several surgical procedures have been proposed for tumors in the anterior parotid gland. Although the standard approach to other parotid tumors is generally also used for anterior tumors, handling of the facial nerve has not been addressed in any previous reports. METHODS: A total of 654 patients with benign parotid tumors who underwent surgery in our department were classified into anterior (AT), middle (MT), and posterior tumor (PT) groups according to tumor location. Clinical characteristics, histopathological types, and frequency of postoperative transient facial palsy were examined. In the AT group, two surgical methods were compared, which were the main trunk method (MTM) and the peripheral method (PM). RESULTS: 172 patients were included in the AT group, 175 in the MT group, and 307 in the PT group. The AT group showed significant female predominance and a higher percentage of deep lobe tumors than the PT group. There was no significant difference in the rate of postoperative transient facial palsy among the AT (MTM), MT, and PT groups. The PM had a significantly shorter operating time and lower rate of transient facial palsy than the MTM. CONCLUSION: The PM for AT was considered a useful surgical method from the standpoints of postoperative complications and operating time. In the PM, a wide operating field made identification of the facial nerve easier.

Increase in Chymase-Positive Mast Cells in Recurrent Pleomorphic Adenoma and Carcinoma Ex Pleomorphic Adenoma of the Parotid Gland.

Incomplete excision of pleomorphic adenoma (PA) may result in recurrent pleomorphic adenoma (RPA). Furthermore, long-term neglected PA may become carcinoma ex pleomorphic adenoma (CXPA). In the present study, the relationships between mast cell-derived chymase and these tumors were examined. The tumor tissues of PA consisted of either or both glandular and fibrotic structures. Histological features of RPA were almost similar to those of PA, except that they showed multinodular structures. CXPA is composed of a mixture of PA and carcinoma. The main stromal cells in PA were myofibroblasts, whereas fibroblasts constituted the main cellular portion in the stromal tissue of RPA. Cancer-associated fibroblasts (CAFs) were present abundantly in CXPA. With increased VEGF expression, neovascularization tended to increase in RPA or CXPA. Compared with PA, chymase-positive mast cells, as well as chymase gene expression, were increased in the tumor tissues from patients with RPA or CXPA. SCF, TGFß1, and PCNA-positive staining was widely observed in these tumor tissues. The above results suggest that mast cell-derived chymase through its direct or cooperative effects with other mediators may participate in the pathophysiology of RPA and CXPA.

Challenges with preoperative diagnosis of low/intermediate-grade carcinoma of the parotid gland: single-center study of 112 patients.

BACKGROUND: The malignancy of parotid carcinoma varies, and accurate preoperative assessment of malignancy is important for selecting the appropriate treatment. However, the preoperative diagnosis of low/intermediate-grade carcinoma is difficult, and surgery may sometimes be performed without any prior knowledge of malignancy. METHODS: The results of fine-needle aspiration cytology (FNA), imaging studies (MRI and US), physical examination, and frozen section biopsy (FSB) were evaluated in 112 patients with low/intermediate-grade parotid carcinoma. RESULTS: The result of FNA was benign/inadequate specimen in 44.6% of the patients. In addition, the tumor was diagnosed as benign by MRI/US in 21.4% of the patients and 37.5% had no symptoms/signs of malignancy on physical examination. The rate of misdiagnosis as benign decreased when FNA was combined with imaging and physical findings. However, malignancy could not be diagnosed by FNA and FSB in 12.5% of the patients who were only found to have malignant tumors by the final pathological examination. CONCLUSION: FNA shows a high misdiagnosis rate of malignancy in patients with low/intermediate-grade cancer. Therefore, it is necessary to carefully evaluate the findings of imaging studies and physical examination, and FSB should be conducted if such findings suggest the possibility of malignancy.

Safety profile and immunological response of dual sublingual immunotherapy with house dust mite tablet and Japanese cedar pollen tablet.

BACKGROUND: There have been no studies of dual administration of sublingual immunotherapy (SLIT) tablets for perennial and seasonal allergic rhinitis. This trial (JapicCTI-184014) was conducted to investigate the safety profile and immunological response during dual therapy with SQ house dust mite (HDM) and Japanese cedar pollen (JCP) SLIT tablets. METHODS: This was a multicenter, open-label, randomized trial of 109 Japanese patients with coexisting HDM and JCP allergic rhinitis who had positive tests for HDM- and JCP specific IgE (≥0.7 kU/L). Patients were allocated to receive HDM (N = 54) or JCP (N = 55) SLIT tablets alone for 4 weeks followed by 8 weeks of dual therapy with both SLIT tablets administered within 5 min of each other. Adverse events (AEs), adverse drug reactions (ADRs), and serum IgE and IgG4 specific for HDM (Dermatophagoides farinae, Dermatophagoides pteronyssinus) and JCP were recorded. RESULTS: The percentage of subjects with AEs and ADRs was similar between the two groups and between the two periods of monotherapy and dual therapy. Most AEs and ADRs were mild in severity, and no serious events were observed. The most common ADRs were local events in the oral cavity. Levels of IgE and IgG4 specific for HDM (D. farinae, D. pteronyssinus) and JCP were increased after treatment with HDM and JCP SLIT tablets, respectively. CONCLUSIONS: Dual therapy with both SLIT tablets administered within 5 min after 4 weeks of monotherapy with HDM or JCP tablet was well tolerated and induced the expected immunological responses.

Adoptive transfer of type 1 regulatory T cells suppressed the development of airway hyperresponsiveness in ovalbumin-induced airway inflammation model mice.

Type 1 regulatory T (Tr1) cells are CD4+ T cells that produce a large amount of IL-10, an anti-inflammatory cytokine. However, it has not been fully elucidated whether Tr1 cells suppress allergic asthma. In this study, the effects of adoptive transfer of in vitro-induced Tr1 cells on allergic asthma were evaluated. Splenocytes from ovalbumin (OVA)-sensitized BALB/c mice were cultured with OVA, IL-21, IL-27, and TGF-ß. After culture, IL-10-producing CD4+ T cells were isolated by Dynabeads mouse CD4 and IL-10 secretion assay, and analyzed by flow cytometry. Purified Tr1 cells (IL-10+ CD4+ T cells) were intravenously injected into OVA-sensitized BALB/c mice. The recipient mice were intratracheally challenged with OVA. Airway hyperresponsiveness to methacholine was assessed by the forced oscillation technique, followed by bronchoalveolar lavage (BAL). Almost all of the induced IL-10-producing CD4+ T cells were negative for interferon-γ, IL-4, IL-17A, and forkhead box P3, suggesting that the cells were Tr1 cells. The adoptive transfer of Tr1 cells significantly suppressed the development of airway hyperresponsiveness, and increases in IL-5, eosinophils, and neutrophils in BAL fluid. In conclusion, we demonstrated that Tr1 cells suppressed allergic asthma in mice.

Patterns of lymph node metastasis and the management of neck dissection for parotid carcinomas: a single-institute experience.

BACKGROUND: There is no consensus about the indications and range of neck dissection in patients who have parotid carcinoma, with elective neck dissection for cN0 disease being particularly controversial. METHODS: This study retrospectively reviewed 185 patients with newly diagnosed parotid carcinoma who were treated at our department between September 1999 and August 2018. RESULTS: 50 of the 185 patients had lymph node metastasis, including 7.7%, 12.2%, 36.0%, and 55.8% of patients with T1, T2, T3, and T4 disease, respectively. When classified by histological grade, 5.7% of patients with low/intermediate-grade disease had lymph node metastasis versus 55.0% of patients with high-grade disease. Multivariate analysis revealed that the histological grade and T classification were independent predictors of lymph node metastasis. Occult metastasis was found in 8 out of 73 clinically node negative patients undergoing neck dissection. The most common site of cervical metastasis was level 2, followed by the periparotid nodes, level 3, and level 4. CONCLUSION: Elective neck dissection may be most appropriate for parotid carcinoma patients with high grade disease and/or an advanced T classification. Because preoperative evaluation of the histological grade of parotid carcinoma has limited reliability, it is important to decide the indications and range of neck dissection from the results of frozen section biopsy.

Clinical characteristics of acinic cell carcinoma and secretory carcinoma of the parotid gland.

PURPOSE: Mammary analogue secretory carcinoma (SC) of the parotid gland is a relatively uncommon cancer associated with the ETV6-NTRK3 fusion product similar to breast cancer. The clinical characteristics and outcome of treatment were reviewed for patients with this tumor at our hospital. METHODS: In this retrospective case series, 24 patients with a diagnosis of acinic cell carcinoma (AcCC) of the parotid gland were classified as having either SC or AcCC based on analysis of the ETV6-NTRK3 fusion gene. These two groups were compared with respect to their clinical and imaging characteristics (MRI/US), cytologic findings, accuracy of fine-needle aspiration cytology and frozen section, treatment outcomes, and immunohistochemical findings. RESULTS: Based on re-classification by ETV6-NTRK3 fusion gene analysis, the diagnosis was SC in 14 patients and AcCC in 10 patients. The SC group had a significantly higher proportion of male patients and was also significantly younger than the AcCC group. Imaging studies revealed that SC was significantly more likely to show internal heterogeneity. Correct grading of both tumors was comparable by fine needle aspiration, with the rate being 60% for AcCC and 50% for SC. Diagnosis by frozen section biopsy diagnosis obtained the correct grade in 90% of the AcCC group and 93% of the SC group. CONCLUSIONS: In 24 patients previously diagnosed with AcCC, re-analysis of the ETV6-NTRK3 fusion product indicated that 14 patients actually had SC. Although AcCC and SC show similarities of their biological aggressiveness and prognosis, patients with SC were significantly more likely to be male and younger.

A clinicopathological study of parotid carcinoma: 18-year review of 171 patients at a single institution.

BACKGROUND: This study investigated the clinical outcomes of patients with parotid carcinoma at a single institution during an 18-year period, with the focus on diagnosis, treatment, and survival. METHODS: The subjects were 171 patients with parotid carcinoma treated at our department during the 18-year period from September 1999 to August 2017. There were 19 patients in stage I, 65 patients in stage II, 22 patients in stage III, and 65 patients in stage IV. The symptoms, preoperative diagnosis, node metastasis, survival rate, prognostic factors, and immunohistological findings were investigated. RESULTS: Preoperative diagnosis of the histological grade by fine-needle aspiration cytology was only possible in 34% of the patients, while the histological grade was correctly determined by frozen section biopsy in 72%. The overall frequency of lymph node metastasis was 29%, with 59% in patients with high-grade carcinoma and only 6% in those with low-/intermediate-grade tumors. The disease-specific 5-year survival rate was 100% for patients in stage I, 95.2% in stage II, 70.4% in stage III, and 45.1% in stage IV. Multivariate analysis showed that the pathological grade was the most important prognostic factor. Immunohistological investigation showed patients with HER-2 or androgen receptor-positive tumors had a significantly worse prognosis. CONCLUSIONS: Although a high-grade tumor is the most important prognostic factor, preoperative diagnosis of the grade was not always accurate. Since advanced cancer has a poor prognosis with a limited response to surgery and radiation therapy, development of new treatment strategies, such as molecular-targeting therapies directed against HER-2 and AR, is required.

[Surgical Management for Benign Parotid Tumors: Review of a 16-year Experience with 633 Patients].

OBJECTIVE: The objective of this study was to analyze the diagnosis and postoperative complications of benign parotid tumors for a series of 633 patients who underwent the same diagnostic methods and operation procedure in a single institute. MATERIALS & METHODS: A series of 633 patients who underwent parotidectomy for benign parotid tumors over a 16-year period was reviewed. RESULTS: There were 345 female and 288 male patients. The site of the tumors was divided among three groups, superficial, deep, and lower pole tumors. The numbers of each type of above tumors were 342, 122, and 169 cases, respectively. The most common pathology of the parotid tumor was a pleomorphic adenoma (372 cases) followed by a Warthin tumor (166 cases). Pleomorphic adenomas and Warthin tumors accounted for 85% of all benign tumors. The accuracy rate of fine needle aspiration cytology (FNAC) for all benign tumors was 71%, 84% for pleomorphic adenomas and 72% for Warthin tumors. Transient facial nerve dysfunction was observed in 130 patients (21%) in 612 cases of primary benign parotid tumors, and only one patient developed a permanent weakness. The incidence of transient facial nerve dysfunction was 18% in superficial tumors, 39% in deep tumors, and 15% in lower pole tumors. Significant risk factors for development of a transient facial palsy were the site of the tumors, the size of the tumors, operation time, and bleeding volume. Among these risk factors, for the site of the tumors, the deep lobe was the most important factor associated with transient facial nerve dysfunction. Transient facial nerve dysfunction recovered within 6 months in 90% of all cases. CONCLUSIONS: The accuracy rate of FNAC for benign parotid tumors was 72%. The incidence of transient facial nerve dysfunction in deep tumors was significantly higher compared to that in superficial and lower pole tumors. According to the rate of facial palsy, operation time, and bleeding volume, benign parotid tumor should be divided among three groups, namely superficial, deep, and lower pole tumors.

Continuous 6-year follow-up study of sensitization to Japanese cedar pollen and onset in schoolchildren.

BACKGROUND: Intra individual longitudinal data has been lacking for IgE-mediated seasonal allergic rhinitis (SAR), especially in young children. Little is known about the development and natural course of SAR in terms of prevalence and incidence rates in schoolchildren. METHODS: In May or June each year from 1994 to 2007, schoolchildren were assessed for serum Japanese cedar pollen (JCP)-IgE and house dust mite (HDM)-IgE levels, and surveyed regarding nasal symptoms. RESULTS: Among the 220 children initially assessed in the first grade, 69 (31.4%) were already sensitized to JCP at first grade and 119 (54.1%) did not develop JCP sensitivity during the 6-year study at all. In the first grade children who were HDM-sensitized but JCP non-sensitized, JCP-IgE level was significantly elevated compared to the JCP and HDM non-sensitized group. This seems to indicate that HDM sensitization was very strongly associated with JCP sensitization. CONCLUSIONS: Elevated serum IgE is a consequence of specific sensitization to HDM and HDM sensitization appeared to develop prior to the start of primary school which distinguishes HDM sensitization from JCP sensitization.

Central node dissection from the perspective of lateral neck node metastasis in papillary thyroid carcinoma.

OBJECTIVES: Controversy exists on how to handle central lymph nodes in papillary thyroid carcinoma, particularly regarding indications for prophylactic central neck dissection (CND). Central node metastases are more difficult to diagnose preoperatively than lateral node metastases. METHODS: We enrolled 493 patients with papillary thyroid carcinoma treated at our department in the past 22 years. Metastatic lymph nodes were diagnosed preoperatively mainly by ultrasonography. In principle, CND was performed for all cases; ipsilateral CND was performed for hemithyroidectomy, and bilateral CND was performed for total thyroidectomy. Lateral neck dissection (levels II to V; LND) was performed for metastases to lateral neck lymph nodes (clinical node (cN) 1b). RESULTS: The cN stage was cN0 in 365 patients, cN1a in 10, and cN1b in 118. Of the 357 patients with stage cN0 who underwent CND, 42.9 % had pathologically positive nodes (pN+) in level VI, and of the 118 with stage cN1b who underwent CND, 78.0 % had pN+ in level VI. Cases with advanced T stage were significantly more common with pN+ in level VI. Level VI metastases were significantly associated with pN+ in level IV. As the total number of pN+ at each level of the lateral neck increased, the rate of patients with pN+ in level VI increased, and in patients with 3 or more pN+, about 85 % had level VI metastases. CONCLUSION: Because about half of the patients with cN0 patients had pN+ in level VI, and the rate of pN+ in level VI in each clinical T stage was 46 to 65 %, prophylactic CND should be performed, considering the various clinical benefits. Central nodes will have metastases in about 80 % of cases with lateral node metastases, requiring more accurate dissection. In lateral node metastases, there is a significant association between metastases in levels IV and VI.

Differential expression of TRKB tyrosine kinase in the two histological types of parotid salivary duct carcinoma with cancer aggressiveness.

Parotid salivary duct carcinoma (SDC) is a rare and aggressive parotid gland carcinoma (PGC). SDC has two origins: de novo and ex pleomorphic adenoma (SDC ex PA); however, because of its rarity, the clinical and molecular features of the two types of SDC are not sufficiently understood. Here, we studied the differences in their clinicopathological and molecular features using clinical specimens while comparing them to those of adenoid cystic carcinoma (AdCC), an intermediate-grade PGC. Clinicopathological analysis of tissues from patients with PGC revealed significant associations between histological types and malignant phenotypes, including nodal metastasis, recurrence, vascular invasion, and neural invasion, and revealed more malignant phenotypes of de novo SDC than of SDC ex PA. The de novo SDC showed a significantly higher frequency of intra-neural invasion (intra-NI) and vascular invasion than AdCC and SDC ex PA. PGCs with high intra-NI were significantly correlated with malignant phenotypes and survival rates. Recently, we observed the overexpression of tropomyosin receptor kinase B (TRKB), a receptor tyrosine kinase, in PGC cells. Here, immunohistochemical and clinicopathological analyses showed that TRKB was highly expressed in SDC cells, particularly de novo SDC cells, and was significantly associated with poor survival and highly malignant phenotypes, including intra-NI and vascular invasion. Collectively, these data show that TRKB expression is significantly elevated in PGC, particularly in de novo SDC, and can be one of the biomarkers of their aggressiveness.

Tumor localization is the important factor for recovery time of postoperative facial nerve paralysis in benign parotid surgery.

OBJECTIVE: Facial nerve paralysis is the most problematic complication of surgery for parotid tumors. This study aimed to examine the progress of recovery from postoperative transient facial nerve paralysis (POFNP). METHODS: Participants were 203 patients who developed POFNP after benign parotid surgery. A Kaplan-Meier showed the progress of recovery from paralysis. Factors involved in recovery were examined. For factors for which a significant difference was found, recovery from paralysis was examined over time. RESULTS: Rates of recovery from paralysis were as follows: 28.6% of patients at 1 month, 58.3% at 3 months, 85.9% at 6 months, and 95.1% at 12 months after surgery. Deep lobe tumors were shown to be significantly associated with delayed recovery from paralysis. The relationship between tumor location and the time of recovery from was that deep lobe tumors had a significantly worse recovery from paralysis at 4 and 5 months after surgery. CONCLUSION: Patients who develop POFNP must be informed about the progress of recovery and factors involved in recovery from paralysis. We believe that the results of the present study are a useful reference to that end.