Effects of Chinese herbs on salivary fluid secretion by isolated and perfused rat submandibular glands

AIM： TO determine whether Chinese herbs （CHs） relieve xerostomia （dry mouth） by increasing salivary secretion. METHODS： The submandibular glands of Wistar rats were surgically isolated and perfused arterially with buffered salt solution. After control perfusion, recording started 5 min prior to the start of stimulation. After fluid secretion was induced by 0.2 μmol/L carbamylcholine （CCh） in the perfusate for 10 min, Chinese herb （CH） was added in the perfusion for 5 min. CCh was then overloaded at 0.2 μmol/L in the perfusion for 20 min. The volume of salivary fluid secretion was recorded by a computer-controlled balance system. RESULTS： Saliva secretion formed an initial ephemeral peak at 30 s followed by a gradual increase to a sustained level. CH alone induced no or little saliva in all types of CH selected. During perfusion with CH,overloading of CCh promoted fluid secretion in 1S of 20 CHs. This promotion was classified into four patterns, which were eventually related to the categories of CH： Overall sustained phase was continuously raised （Yin-nourishing, fluid production-promoting and heatclearing agents）; The sustained secretion rose to reach a maximum then decreased （Qi-enhancing agent）; Sustained secretion rose to reach the highest maximum and was then sustained with a slight decline （swelling-reducing, phlegm-resolving and pus-expelling agents）; Stimulation of salivary secretion without any added stimulants. Addition of CCh raised the fluid secretion to reach the highest maximum then sharply decreased to a lower sustained level （blood activating agent）. CONCLUSION： The present findings lead to the conclusion that various CHs have different promotional effects directly on the salivary gland.

Botulinum toxin A inhibits salivary secretion of rabbit submandibular gland

Botulinum toxin A （BTXA） has been used in several clinical trials to treat excessive glandular secretion; however, the precise mechanism of its action on the secretory function of salivary gland has not been fully elucidated. In this study, we aimed to investigate the effect of BTXA on secretion of submandibular gland in rabbits and to identify its mechanism of action on the secretory function of salivary gland. At 12 weeks after injection with 5 units of BTXA, we found a significant decrease in the saliva flow from submandibular glands, while the salivary amylase concentration increased. Morphological analysis revealed reduction in the size of acinar cells with intracellular accumulation of secretory granules that coalesced to form a large ovoid structure. Expression of M3-muscarinic acetylcholine receptor （M3 receptor） and aquaporin-5 （AQP5） mRNA decreased after BTXA treatment, and distribution of AQP5 in the apical membrane was reduced at 1, 2 and 4 weeks after BTXA injection. Furthermore, BTXA injection was found to induce apoptosis of acini. These results indicate that BTXA decreases the fluid secretion of submandibular glands and increases the concentration of amylase in saliva. Decreased expression of M3 receptor and AQP5, inhibition of AQP5 translocation, and cell apoptosis might involve in BTXA-reduced fluid secretion of submandibular lands.

Salivary duct carcinoma of the submandibular gland presenting a diagnostic challenge: A case report

BACKGROUND Salivary duct carcinoma(SDC)is a rare,extremely aggressive malignancy that arises in the submandibular gland.It can metastasize locally early and therefore is an important differential diagnosis of metastatic disease in cervical lymph nodes or specific lymphadenitis such as tuberculous cervical lymphadenitis.CASE SUMMARY We report a case of SDC in the submandibular gland that presented diagnostic difficulty.The lesion was coincidentally discovered through examination of the radiolucent area of the maxilla.Imaging failed to confirm the possibility of specific inflammation,leading us to execute an open biopsy to verify the diagnosis.The surgical specimen showed that the submandibular gland was primarily replaced with a calcified body.Following histological analysis and confirmation,we performed surgical resection,radiotherapy,and various chemotherapies.CONCLUSION Radiographic imaging characteristics of lymph node metastases of salivary gland cancer,especially of SDC,may resemble other cervical lymphadenitis;calcification at the submandibular gland is the landmark of SDC occurring at the submandibular gland.

Overall and cause-specific survival for mucoepidermoid carcinoma of the major salivary glands:Analysis of 2210 patients

BACKGROUND Mucoepidermoid carcinoma(MEC)is a rare malignancy of the head and neck;however,it accounts for a majority of the tumors of the salivary glands.This study used a national population-based registry to describe the pre-treatment and treatment-related prognostic factors that influence survival in patients with MEC of the major salivary glands.To our knowledge,this is the largest populationbased study examining predictors of both overall and cause-specific survival of MEC of the major salivary glands.AIM To identify prognostic factors influencing overall survival(OS)and cause-specific survival(CSS)of patients with MEC of the major salivary glands.METHODS We used the Surveillance,Epidemiology and End-Results Database of the National Cancer Institute to investigate a variety of factors that could influence survival of patients diagnosed with mucoepidermoid carcinoma of the major salivary glands.A total of 2210 patients diagnosed with MEC of the major salivary glands during the years of 1975-2016 were studied.The primary endpoints were OS and CSS.Cox regression analysis was used to perform univariate and multivariate analyses of clinical variables such as age at diagnosis,diagnosis year,sex,race,tumor size,stage,grade,treatment with or without surgical excision,and adjuvant radiotherapy treatment.RESULTS A total of 2210 patients diagnosed with MEC of the major salivary glands met inclusion criteria.In this study,95%of patients underwent surgical excision and 41%received adjuvant radiation therapy.Median OS time for Grade I,II,and III/IV was 401 mo(±48.25,95%CI),340 mo(±33.68,95%CI)and 55 mo(±11.05,95%CI),respectively.Univariate analysis revealed that lack of surgical excision was associated with decreased OS[hazard ratio(HR)4.26,P<0.0001]and that patients with localized disease had improved OS compared to both regional and distant disease(HR 3.07 and 6.96,respectively,P<0.0001).Additionally,univariate analysis demonstrated that male sex,age over 50 at diagnosis,Grade III tumors,and increasing tumor size were associated with worsened OS(P<0.0006).Univariate analysis of CSS similarly revealed that lack of surgical excision and Grade III carcinoma conferred decreased CSS(HR 4.37 and 5.44,respectively,P<0.0001).Multivariate analysis confirmed that increasing age,in 10-year age bands,advanced tumor stage,increasing tumor size,Grade III carcinoma,male sex,and lack of surgical excision were associated with a statistically significant decrease in OS and CSS(P<0.04).Of note,multivariate analysis revealed that the use of adjuvant radiation therapy was not associated with improved OS or CSS.CONCLUSION Multivariate analysis demonstrated increasing age,advanced tumor stage,increasing tumor size,Grade III carcinoma,male sex,and lack of surgical excision were associated with decreased OS and CSS(P<0.04).

Localization and potential function of androgen receptor in rat salivary gland

Aim： To investigate the localization and quantity of androgen receptor （AR） in the salivary glands of rats with further analysis on the effect of castration. Methods： Sixty male Wistar rats, aged 30-60 days, were randomly divided into three groups （castrated, sham-operated and normal controls） with 20 rats in each group. The rats in the castrated group were castrated and the submaxillary glands were removed after 1 week. The salivary glands of the rats in the sham-operated and the normal control groups were also removed. Parts of the salivary glands were fixed for immuohistochemistry and in situ hybridization assays. Other parts were used for Western blot. Results： AR immunoreactivity in the three groups was localized in the glandular epithelial cells of the serous acinus and the glandular duct of the salivary gland, mainly in the nuclei. AR mRNA hybridization signals in the salivary glands of the castrated group were mainly distributed in the epithelial cells of the convoluted and secretary ducts; AR mRNA in the sham-operated and the normal control groups were found in the epithelial cells of the convoluted, the secretary and the excretory ducts. The quantity of AR in the salivary glands was decreased significantly in the castrated rats compared with the sham-operated and the normal controls. Moreover, epidermal growth factor （EGF） secreted by the salivary glands was also decreased in the castrated rats. Conclusion： Castration appears to affect the production of AR in the salivary gland and the distribution of the AR mRNA and could further affect the function of the salivary gland. The changes of AR and the distribution of AR mRNA may play an important role in the interactions between the testes and the salivary gland. （Asian J Androl 2005 Sep; 7： 295-301）

The effect of basic fibroblast growth factor on regeneration in a surgical wound model of rat submandibular glands

This study developed an animal model of surgically wounded submandibular glands （SMGs） and investigated the effects of collagen gel with basic fibroblast growth factor （bFGF） on tissue regeneration of surgically wounded SMGs in vivo. The animal model was produced by creating a surgical wound using a 3-mm diameter biopsy punch in SMGs. The wound was filled with collagen gel with bFGF （bFGF group） or without bFGF （control group）. In the animal model of surgically wounded SMGs, salivary glands without scar tissue around the wound area were observed with smaller areas of collagen gel. Small round and spindle-shape cells invaded the collagen gel in both groups after operation day （AOD） 5, and this invasion dramatically increased at AOD 7. Host tissue completely replaced the collagen gel at AOD 21. The invading immune cells in the group treated with collagen gel with bFGF were positive for vimentin, g-smooth muscle actin （αSMA）, CD49f, c-kit and AQP5 at AOD 7. Similarly, the mRNA expression of vimentin, αSMA, CD49f, keratin 19 and AQP5 was also increased. This study suggests that the use of collagen gels with bFGF improves salivary gland regeneration.

The oncofetal protein IMP3 is an indicator of early recurrence and poor outcome in mucoepidermoid carcinoma of salivary glands

Objective: Mucoepidermoid carcinoma(MEC) is the most common primary malignancy of the salivary glands. Insulin-like growth factor-II m RNA-binding protein-3(IMP3) is an important prognostic factor in some cancers and a tool that differentiates between benign and malignant pancreatic lesions. This study aimed to identify a relationship between the expression of IMP3 and the outcome of salivary gland MEC, as well as to differentiate MEC from pleomorphic adenoma(PA).Methods: Tissue specimens from 70 cases of salivary gland MEC, 40 cases of PA, and 10 cases with normal salivary gland were examined immunohistochemically for IMP3. The association among the expression of IMP3, clinicopathological characteristics and patient's survival was assessed.Results: IMP3 was present in 51.4% of MEC but absent in PA and normal salivary gland tissues. IMP3 expression was associated with age > 60 years, submandibular gland tumors, tumor size > 4 cm, high-grade tumors, lymph node metastasis, involvement of surgical margins, perineural invasion, distant metastasis, advanced TNM stage, tumor relapse, and death(P<0.05). Increased expression of IMP3, tumors of the submandibular gland, and lymph node metastasis were independent prognostic factors of disease-free survival(DFS). In addition, IMP3 was a strong predictor of overall survival(OS) together with distant metastasis and intermediate and high-grade tumors.Conclusions: IMP3 expression is highly important in evaluating the outcome of MEC. IMP3 can be used to differentiate MEC from PA of salivary glands.

Autoimmune pancreatitis with IgG4-positive plasma cell infiltration in salivary glands and biliary tract

A 62-year-old male was referred to our hospital because of liver dysfunction, diffuse pancreatic swelling, and trachelophyma. At admission, the patient was free of pain. Physical examination showed enlarged and palpable bilateral submandibular masses, but no palpable mass or organomegaly in the abdomen. Laboratory findings were as follows： total protein 90 g/L with γ-globulin of 37.3% （33 g/L）, total bilirubin 4 mg/L, aspartate aminotransferase 39 IU/L, alanine aminotransferase 67 IU/L,γ-glutamyl transpeptidase 1 647 IU/L, and amylase 135 IU/L. Autoantibodies were negative, and tumor markers were within the normal range. Serum IgG4 level was markedly elevated （18 900 rag/L）. Computed tomography （CT） showed diffuse swelling of the pancreas and dilatation of both common and intra-hepatic bile ducts. Endoscopic retrograde pancreatography （ERP） revealed diffuse irregular and narrow main pancreatic duct and stenosis of the lower common bile duct. Biopsy specimens from the pancreas, salivary gland and liver showed marked periductal IgG4-positive plasma cell infiltration with fibrosis. We considered this patient to be autoimmune pancreatitis （AIP） with fibrosclerosis of the salivary gland and biliary tract, prescribed prednisolone at an initial dose of 40 mg/d. Three months later, the laboratory data improved almost to normal. Abdominal CT reflected prominent improvement in the pancreatic lesion. Swelling of the salivary gland also improved. At present, the patient is on 10 mg/d of prednisolone without recurrence of the pancreatitis. We present here a case of AIP with fibrosclerosis of salivary gland and biliary tract.

Salivary Gland Branching Morphogenesis——Recent Progress and Future Opportunities

Salivary glands provide saliva to maintain oral health, and a loss of salivary gland function substantially decreases quality-of-life. Understanding the biological mechanisms that generate salivary glands during embryonic development may identify novel ways to regenerate function or design artificial salivary glands. This review article summarizes current research on the process of branchingmorphogenesis of salivary glands, which creates gland structure during development. We highlight exciting new advances and opportunities in studies of cell-cell interactions, mechanical forces, growth factors, and gene expression patterns to improve our understanding of this important process.

Quantitative Study on Expression of P16 Multiple Tumor Suppressor Gene in Salivary Gland Neoplasm

The expression of P16 gene were found in all 3 groups. The positive unit (PU) was higher in tumor group and cancer group than that in normal group ( P <0.01). Furthermore, the PU of P16 was stronger in cytoplasm than in nucleus. Malignant tumors and acini surrounding the tumor revealed strong positives and week positives respectively. The PU of P16 gene was higher in deep lobe of recurrent parotid neoplasm with incomplete capsule than that in shallow lobe of primary parotid neoplasm with complete capsule. Our findings suggests that P16 gene plays equally important role in the salivary gland tumors and tumors in other part of the body.

Expression of cyclin-dependent kinase inhibitor 2A 16,tumour protein 53 and epidermal growth factor receptor in salivary gland carcinomas is not associated with oncogenic virus infection

It is known that human papillomavirus （HPV） infection can cause squamous cell neoplasms at several sites, such as cervix uteri carcinoma and oral squamous carcinoma. There is little information on the expression of HPV and its predictive markers in tumours of the major and minor salivary glands of the head and neck. We therefore assessed oral salivary gland neoplasms to identify associations between HPV and infection-related epidermal growth factor receptor （EGFR）, cyclin-dependent kinase inhibitor 2A （CDKN2A/p16） and tumour protein p53 （TP53）. Formalin-fixed, paraffin-embedded tissue samples from oral salivary gland carcinomas （n=51） and benign tumours （n=26） were analysed by polymerase chain reaction （PCR） analysis for several HPV species, including high-risk types 16 and 18. Evaluation of EGFR, CDKN2A, TP53 and cytomegalovirus （CMV） was performed by immunohistochemistry. Epstein-Barr virus （EBV） was evaluated by EBV-encoded RNA in situ hybridisation. We demonstrated that salivary gland tumours are not associated with HPV infection. The expression of EGFR, CDKN2A and TP53 may be associated with tumour pathology but is not induced by HPV. CMV and EBV were not detectable. In contrast to oral squamous cell carcinomas, HPV, CMV and EBV infections are not associated with malignant or benign neoplastic lesions of the salivary glands.

RNAi knockdown of C-erbB2 expression inhibits salivary gland adenoid cystic carcinoma SACC-83 cell growthin vitro

Objective：To knockdown the C-erbB2 gene in salivary gland adenoid cystic carcinoma SACC-83 cells using RNA interference,and determine the effect of silencing C-erbB2 on cell proliferation.Methods：C-erbB2-siRNA was transfected into SACC-83 cells.RT-PCR and immunohistochemistry were used to detect C-erbB2 expression in SACC-83 cells.Cell proliferation was measured by the MTT assay and gene knockdown was achieved by RNA interference.Apoptosis was analyzed by flow cytometry.Results：Compared with the control,C-erbB2 mRNA expression was decreased in the C-erbB2-siRNA transfection group,and immunohistochemical analysis indicated that C-erbB2 protein expression was decreased.After C-erbB2-siRNA was transfected for 48 h,absorbance at 570 nm （MTT）was 0.185±0.021 compared with 0.354±0.034,0.299±0.053,and 0.314±0.049 in the blank control,liposome control and negative control siRNA groups,respectively.The differences were statistically significant （P〈0.05）between the C-erbB2-siRNA group and the control groups.Following the C-erbB2 knockdown,the percentage of apoptotic cells was 5.63%compared with 2.04%,2.85%,and 2.98%in the three control groups,respectively.Proliferation of SACC-83 cells was inhibited,and early apoptotic cells were increased.Conclusion： RNA interference can effectively silence C-erbB2 gene expression and inhibit growth of SACC-83 cells,which indicates the potential of targeting this gene as a novel gene therapy approach for the treatment of salivary gland adenoid cystic carcinoma.

Advanced magnetic resonance imaging findings in salivary gland tumors

Salivary gland tumors(SGTs)make up a small portion(approximately 5%)of all head and neck tumors.Most of them are located in the parotid glands,while they are less frequently located in the submandibular glands,minor salivary glands or sublingual gland.The incidence of malignant or benign tumors(BTs)in the salivary glands varies according to the salivary gland from which they originate.While most of those detected in the parotid gland tend to be benign,the incidence of malignancy increases in other glands.The use of magnetic resonance imaging(MRI)in the diagnosis of SGTs is increasing every day.While conventional sequences provide sufficient data on the presence,localization,extent and number of the tumor,they are insufficient for tumor specification.With the widespread use of advanced techniques such as diffusion-weighted imaging,semiquantitative and quantitative perfusion MRI,studies and data have been published on the differentiation of malignant or BTs and the specificity of their subtypes.With diffusion MRI,differentiation can be made by utilizing the cellularity and microstructural properties of tumors.For example,SGTs such as high cellular Warthin’s tumor(WT)or lymphoma on diffusion MRI have been reported to have significantly lower apparent diffusion values than other tumors.Contrast agent uptake and wash-out levels of tumors can be detected with semiquantitative perfusion MRI.For example,it is reported that almost all of the pleomorphic adenomas show an increasing enhancement time intensity curve and do not wash-out.On quantitative perfusion MRI studies using perfusion parameters such as Ktrans,Kep,and Ve,it is reported that WTs can show higher Kep and lower Ve values than other tumors.In this study,the contribution of advanced MRI to the diagnosis and differential diagnosis of SGTs will be reviewed.

Prospect of Functional Salivary Gland Enhancement with Biomedical Strategies for Head and Neck Cancers

Xerostomia is the main complication inflicting head and neck cancer patients treated with radiotherapy.Conventional treatment is not very effective in alleviating this morbidity.Biomedical strategies such as gene transfer and tissue engineering have made substantial progress that will potentially lead to successful new treatment options for this condition.This report reviews the process of radiation damage to the salivary glands and the advances in functional salivary gland enhancement with these two brand-new technologies.

30-bp DELETION IN LATENT MEMBRANE PROTEIN 1 (LMP-1) ONCOGENE IN LYMPHOEPITHELIAL CARCINOMA OF SALIVARY GLANDS

Objective: To investigate the 30 bp deletion in LMP-1 in lymphoepithelial carcinoma of salivary glands, and to clarify the deletion rate. Methods: 46 cases of LEC were subjected to PCR examination for the 3?terminal region of LMP-1 gene, in order to observe the 30 bp deletion. To reduce the influence of unsuccessful DNA extraction from paraffin-embedded tissue sections, a bactin PCR was performed at the same time. Additionally, DNA sequencing was performed on 1 case without deletion and 1 case with deletion. Results: 4 of 46 specimens were proved to contain no suitable DNA sample by bactin gene amplification. In the remaining 42 cases, LMP-1 DNA was detected in 35/42 (83.3%) LEC cases. Two kinds of PCR products were found in these 35 cases after further DNA sequencing. 31 cases (88.6%) carried 316 bp product and 4 cases (11.4%) carried 286 bp product. Conclusion: Some LECs of salivary glands carry del-LMP-1. In our study, the deletion rate was 11.4% (4/35).

Inhibition of Salidroside on Salivary Gland Adenoid Cystic Carcinoma

To evaluate the role of salidroside on proliferation,apoptosis and invasiveness of salivary gland adenoid cystic carcinoma cells（SACC）,immunocytochemical staining was employed to detect proliferating cell nuclear antigen（PCNA）,caspase 3 and caspase 8 expression in SACC-2 cells.Modified Boyden chamber assay combined with laser confocal microscopy（LSCM） was used to evaluate the invasion and migration abilities of SACC-2 cells at different time point.Immunohistochemistry staining revealed that the expression of PCNA was significantly decreased（P0.01） after salidroside treatment.In contrast,salidroside treatment led to increased caspase 3 and caspase 8 in SACC-2 cells.Cell migration depth and number of cells that penetrated Boyden chamber were also decreased by salidroside.Salidroside potently inhibits the proliferation and simultaneously induces the apoptosis of SACC-2 cells.Migration and invasion of SACC-2 cells are also inhibited.Our data throw light on potential clinical application of salidroside to the patients with SACC.

Influence of the Radiation Dose to Salivary Glands on Xerostomia in Patients with Head and Neck Carcinomas

Purpose: Investigation of the influence of radiation dose to salivary glands on xerostomia in patients with head and neck cancers. Methods: From October 2002 to December 2011, 548 patients with head and neck carcinomas were treated in our department using intensity modulated radiotherapy (IMRT). 325 patients were eligible for analysis more than 1 year after irradiation. Xerostomia was evaluated according to the criteria of Radiation Therapy and Oncology Group (RTOG) and xerostomia related questionnaire. For statistical analysis grade 1 and 2 were recorded as mild and grade 3 and 4 as severe xerostomia. The dosimetric values for absolute mean dose, biological equivalent mean dose (EQD2), the relative organ volume not exceeding 20 Gy, 25 Gy and 30 Gy (V20, V25, V30) for all 4 major salivary glands or for both parotid glands only were used for analysis. V20 revealed the best discrimination between both patient groups (with vs. without xerostomia), compared to parameters V25 and V30. Therefore the volume of the salivary glands receiving less than 20 Gy (V 20Gy) was analyzed additionally. Mann-Whitney-U-test, Kruskal-Wallis-test and logistic regression were used in statistical analysis. Results: A TD 50 can be determined for the occurrence of xerostomia more than one year after radiotherapy for both parotid glands of 19.3 Gy for the mean dose absolute, 11.2 Gy for the mean dose EQD2, 38.2% for V20, 26.8% for V25, 18.7% for V30, 34.9 ml for V 20Gy. For all major salivary glands theses values were 25.7 Gy for the mean dose absolute, 15.6 Gy for the mean dose EQD2, 51.3% for V20, 41.1% for V25, 33.9% for V30 and 34.8 ml for V 20Gy. Conclusions: The identification of a tolerance dose for the salivary glands for treatment planning appears to be difficult, as the dose-response correlation only shows a flat slope. Additionally, a large interindividual variability seems to exist. We could not found any threshold dose for development of xerostomia.

Hyperglycemia Induced Apoptosis Changes in Salivary Gland Cells of Mice

If the function of salivary glands that secrete saliva is degraded, saliva secretion will decrease and symptoms of xerostomia will appear. Although symptoms of xerostomia are often felt by patients with diabetes, the relationship between diabetes and xerostomia is currently unclear. In relation to DM, there are studies on salivation flow and saliva composition, but there are not studies of apoptosis of salivary gland cells. The objective of this study was to investigate whether apoptosis in salivary glands of mice with hyperglycemic, a symptom of diabetes, might be altered based on immunohistochemical analysis. This study used mice with hyperglycemia. Immunohistochemistry and Western blot analyses were performed using Fas, Bax, and cleaved caspase-3 antibodies. These antibodies are used not only as death receptors, but also are antibodies that activate upstream and downstream signals of apoptosis. TUNEL assay was performed to detect apoptosis by immunofluorescence using TdT enzyme. It was observed that the expression level of apoptosis signaling molecules and TUNEL positive cells were increased in hyperglycemia group (HG). As a result, there are many apoptosis cells in the HG groups of the salivary gland. The results of this study, the function of salivary gland could occur deteriorated due to apoptosis on salivary gland cells by hyperglycemic, a characteristic of diabetes.

Relevance on the diagnosis of malignant lymphoma of the salivary gland

Malignant lymphoma originates from the lymphohematopoietic system.It can occur in any lymphoid tissue.Malignant lymphoma of the salivary gland is rare,but its incidence has increased in recent years.Its clinical-presentations are nonspecific,and it is often manifested as a painless mass in a salivary gland,which can be accompanied by multiple swollen cervical lymph nodes.Confirmation of the diagnosis before an invasive procedure is difficult.Clinically,malignant lymphoma of the salivary gland tends to be misdiagnosed,leading to an inappropriate treatment plan and the ultimate delay in the optimal treatment of the disease.This article reviews the pathogenesis,clinical features,imaging findings,diagnosis,treatment and prognosis of malignant lymphoma of the salivary gland.

Postoperative radiotherapy for thymus salivary gland carcinoma:A case report

BACKGROUND Salivary gland cancer is a rare disease in which cancer cells form in the tissues of the salivary glands.It mostly occurs in the glands that have secretion functions,such as the parotid gland,sublingual gland and submandibular gland.This is very rare when it occurs in other nonsecreting glands.Here,we report one case of salivary gland carcinoma occurring in the thymus and discuss related diagnoses and treatment progress.CASE SUMMARY One 33-year-old middle-aged man presented with a thymus mass without any clinical symptoms when he underwent regular physical examination.Later,the patient was admitted to the hospital for further examination.Computed tomography(CT)showed that there was a mass of 3 cm×2.8 cm×1.5 cm in the thymus area.The patient had no symptom of discomfort or tumor-related medical history before.After completing the preoperative examinations,it was confirmed that the patient had indications for surgery.The surgeon performed a transthoracoscope"thymectomy+pleural mucostomy"for him.During the operation,the tumor tissue was quickly frozen,and the symptomatic section showed a malignant tumor.The final pathological result suggested thymus salivary gland carcinoma-mucoepidermoid carcinoma(MEC).In the second month after surgery,we performed local area radiotherapy for the patient,with a total radiation dose of 50.4 Gy/28Fx.After 12 mo of surgery,the patient underwent positron emission tomography-CT examination,which indicated that there was no sign of tumor recurrence or metastasis.After 16 mo of operation,CT scan re-examination showed that there was no sign of tumor recurrence or metastasis.As of the time of publication,the patient was followed up for one and a half years.He had no sign of tumor recurrence and continued to survive.CONCLUSION The incidence of MEC in the thymus is low,and its diagnosis needs to be combined with clinical features and imaging methods.Histopathological analysis plays a key role in the diagnosis of the disease.Patients with early-stage disease have a good prognosis and long survival period.In contrast,patients with advanced-stage disease have a poor prognosis and short survival period.Combining radiotherapy and chemotherapy in inoperable patients may prolong survival.