Review of the Major and Minor Salivary Glands, Part 2: Neoplasms and Tumor-like Lesions

Imaging Spectrum of Extrathyroidal Neck Masses

ABSTRACT

Extrathyroidal masses in the anterolateral neck are frequently encountered in the adult population and may represent a diagnostic dilemma. These neck masses can result from a diverse array of pathologies including congenital, inflammatory, infectious, and neoplastic causes. Relevant medical history and physical examination are essential to complement the imaging findings. Ultrasound (US) plays an important role in the initial evaluation of neck masses due to its reliability, availability, safety and cost-effectiveness. It can confirm or exclude the presence of a mass and initially characterize it as solid or cystic. Sonographically assessing the relationship of a mass to adjacent cervical anatomy can facilitate a more targeted differential diagnosis. US also effectively guides fine needle aspirations and/or biopsies of accessible lesions. Multimodality imaging is reserved for problem-solving complex cases and presurgical planning. The anterolateral neck masses are categorized into midline/paramedian lesions, salivary gland pathologies, and other soft tissue lesions. Midline and paramedian lesions include thyroglossal duct pathologies, ectopic thyroid tissue, and parathyroid adenomas. Salivary gland pathologies include obstructive/inflammatory processes, benign and malignant neoplasms, and systemic diseases. This pictorial essay presents clinical features and sonographic characteristics of extrathyroidal masses in the anterolateral neck with a brief discussion of other imaging modalities.

Pediatric Salivary Gland Pathology

Benign and malignant salivary gland disorders are uncommon in the pediatric population; however, these can be frequently seen in pediatric otolaryngology or oral and maxillofacial surgery practices. The astute clinician should be aware of the clinical presentation, diagnosis, and management options for common inflammatory, infectious, benign, and malignant disorders of salivary glands.

Performance of radiomics in the differential diagnosis of parotid tumors: a systematic review

Purpose

A systematic review and meta-analysis were conducted to evaluate the diagnostic precision of radiomics in the differential diagnosis of parotid tumors, considering the increasing utilization of radiomics in tumor diagnosis. Although some researchers have attempted to apply radiomics in this context, there is ongoing debate regarding its accuracy.

Methods

Databases of PubMed, Cochrane, EMBASE, and Web of Science up to May 29, 2024 were systematically searched. The quality of included primary studies was assessed using the Radiomics Quality Score (RQS) checklist. The meta-analysis was performed utilizing a bivariate mixed-effects model.

Results

A total of 39 primary studies were incorporated. The machine learning model relying on MRI radiomics for diagnosis malignant tumors of the parotid gland, demonstrated a sensitivity of 0.80 [95% CI: 0.74, 0.86], SROC of 0.89 [95% CI: 0.27-0.99] in the validation set. The machine learning model based on MRI radiomics for diagnosis malignant tumors of the parotid gland, exhibited a sensitivity of 0.83[95% CI: 0.76, 0.88], SROC of 0.89 [95% CI: 0.17-1.00] in the validation set. The models also demonstrated high predictive accuracy for benign lesions.

Conclusion

There is great potential for radiomics-based models to improve the accuracy of diagnosing benign and malignant tumors of the parotid gland. To further enhance this potential, future studies should consider implementing standardized radiomics-based features, adopting more robust feature selection methods, and utilizing advanced model development tools. These measures can significantly improve the diagnostic accuracy of artificial intelligence algorithms in distinguishing between benign and malignant tumors of the parotid gland.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42023434931.

Translational Insights in the Landscape of Salivary Gland Cancers: Ready for a New Era?

Salivary gland carcinomas (SGCs) are rare neoplasms, representing less than 10% of all head and neck tumors, but they are extremely heterogeneous from the histological point of view, their clinical behavior, and their genetics. The guidelines regarding their treatment include surgery in most cases, which can also play an important role in oligometastatic disease. Where surgery cannot be used, systemic therapy comes into play. Systemic therapy for many years has been represented by polychemotherapy, but recently, with the affirmation of translational research, it can also count on targeted therapy, at least in some subtypes of SGCs. Interestingly, in some SGC histotypes, predominant mutations have been identified, which in some cases behave as "driver mutations", namely mutations capable of governing the carcinogenesis process. Targeting these driver mutations may be an effective therapeutic strategy. Nonetheless, it is not always possible to have drugs suitable for targeting driver mutations-and targeting driver mutations is not always accompanied by a clinical benefit. In this review, we will analyze the main mutations predominant in the various histotypes of SGCs.

Pathogenesis Analysis of Salivary Gland Tumors Through the Expression of Programmed Death-Ligand 1 (PD-L1)

Pleomorphic adenoma (PA) is the most common salivary gland neoplasm, followed by Warthin's tumor (WT). In addition to its high frequency, PA also shows metastasis and transformation towards malignancy as carcinoma ex-pleomorphic adenoma (CXPA). While the histogenesis of WT remains unclear, especially given the presence of lymphoid stroma around the developing tumor and the immunological interaction between them. Immune escape is a carcinogenesis mechanism of tumors to avoid the host immune system by producing PD-L1. This study was conducted to determine whether there is an immune escape through the expression of PD-L1 in salivary gland tumors. The tissue sections of PA, CXPA, and WT were stained with Hematoxylin Eosin and immunostained with a rabbit monoclonal recombinant anti-PD-L1 antibody. We observed immunopositive PD-L1 on the cell membrane with or without cytoplasm staining. PA and CXPA expressed PD-L1, accompanied by an anomaly expression of CXPA in several spots at the salivary gland at the surgical border. Therefore, PD-L1 is one of the PA pathways to transform into CXPA through immune escape. WT expressed PD-L1 in the cytoplasm and lymphoid stroma but not on the cell membrane. It is interpreted as positive constitutive, which may have the function of increasing tumor cell growth, while overexpressed PD-L1 in lymphoid stroma is thought to be associated with a poor prognosis of the tumor and is suspected to transform into malignancy, such as B-cell Lymphoma.

Irreversible facial nerve palsy as a revelator ofparotid gland cancer

<br><b>Introduction:</b> Bell's palsy is still the diagnosis of exclusion. In most patients it does not progress, it is unilateral, and selflimiting. Additionally, the majority of patients recover spontaneously within 3 weeks. It is well known that all patients with irreversible facial nerve paresis (FNP) need further examinations to exclude the organic, infectious, metabolic, and autoimmunological causes of the palsy. The goal of the study was to assess the frequency of malignancies hidden under the diagnosis of "Bell's palsy".</br> <br><b>Aim:</b> We aimed to create a diagnostic algorithm to avoid failures concerning patients whose only symptom of parotid gland cancer was irreversible FNP.</br> <br><b>Material and methods:</b> We analyzed 253 consecutive patients with FNP treated in our department in the last 5 years. The subject of the study was "Bell's palsy" cases. All patients with irreversible FNP were reassessed in 6-12 months. We underlined all shortcomings in the diagnostics of those in whom malignancies were found in MRI of the neck and presented the proposal for a diagnostic algorithm to avoid missing such an entity.</br> <br><b>Results:</b> Bell's palsy was observed in 157/253 patients (62.06%), in 36/157 (22.92%) it remained permanent. In 4/36 patients (11.11%) with irreversible FNP, which constituted 2.54% of all "Bell's palsy" cases, parotid gland deep lobe mass was found in MRI. In one patient, infiltration of the skull base was diagnosed. Adenoid cystic carcinoma was confirmed in final histopathology in all cases.</br> <br><b>Conclusions:</b> Our experience has shown that irreversible FNP can be a revelator of the malignant tumor located in the deep lobe of the parotid gland. Contrast-enhanced MRI covering intra- and extracranial segments of the facial nerve should be ordered in all cases of FNP without recovery after 4 months. Repeated imaging should be considered in undiagnosed cases. The main point of our study is to underline that the assessment of the deep lobe of the parotid gland with MRI should be included in the standard diagnostic protocol in all irreversible "Bell's palsy" cases.</br>.

CT-based radiomics with various classifiers for histological differentiation of parotid gland tumors

Objective

This study assessed whether radiomics features could stratify parotid gland tumours accurately based on only noncontrast CT images and validated the best classifier of different radiomics models.

Methods

In this single-centre study, we retrospectively recruited 249 patients with a diagnosis of pleomorphic adenoma (PA), Warthin tumour (WT), basal cell adenoma (BCA) or malignant parotid gland tumours (MPGTs) from June 2020 to August 2022. Each patient was randomly classified into training and testing cohorts at a ratio of 7:3, and then, pairwise comparisons in different parotid tumour groups were performed. CT images were transferred to 3D-Slicer software and the region of interest was manually drawn for feature extraction. Feature selection methods were performed using the intraclass correlation coefficient, t test and least absolute shrinkage and selection operator. Five common classifiers, namely, random forest (RF), support vector machine (SVM), logistic regression (LR), K-nearest neighbours (KNN) and general Bayesian network (Gnb), were selected to build different radiomics models. The receiver operating characteristic curve, area under the curve (AUC), accuracy, sensitivity, specificity and F-1 score were used to assess the prediction performances of these models. The calibration of the model was calculated by the Hosmer–Lemeshow test. DeLong’s test was utilized for comparing the AUCs.

Results

The radiomics model based on the RF, SVM, Gnb, LR, LR and RF classifiers obtained the highest AUC in differentiating PA from MPGTs, WT from MPGTs, BCA from MPGTs, PA from WT, PA from BCA, and WT from BCA, respectively. Accordingly, the AUC and the accuracy of the model for each classifier were 0.834 and 0.71, 0.893 and 0.79, 0.844 and 0.79, 0.902 and 0.88, 0.602 and 0.68, and 0.861 and 0.94, respectively.

Conclusion

Our study demonstrated that noncontrast CT-based radiomics could stratify refined pathological types of parotid tumours well but could not sufficiently differentiate PA from BCA. Different classifiers had the best diagnostic performance for different parotid tumours. Our study findings add to the current knowledge on the differential diagnosis of parotid tumours.

A molecular guide to systemic therapy in salivary gland carcinoma

Salivary gland carcinomas (SGC) are a rare and variable group of head and neck cancers with historically poor response to cytotoxic chemotherapy and immunotherapy in the recurrent, advanced, and metastatic settings. In the last decade, a number of targetable molecular alterations have been identified in SGCs including HER2 upregulation, androgen receptor overexpression, Notch receptor activation, NTRK gene fusions, and RET alterations which have dramatically improved treatment outcomes in this disease. Here, we review the landscape of precision therapy in SGC including current options for systemic management, ongoing clinical trials, and promising future directions.

Magnetic resonance imaging of parotid gland tumors: a pictorial essay

Imaging of parotid gland tumors is challenging due to the wide variety of differential diagnoses. Malignant parotid tumors can have very similar features to benign ones, such as slow growth and displacement instead of infiltration of neighboring structures. Malignant and benign tumors may therefore not be clinically distinguishable. Correct characterization of parotid tumors (i.e., benign or malignant) determines preoperative treatment planning and is important in optimizing the individualized surgical plan. Magnetic resonance imaging (MRI) is the imaging modality of choice for evaluation of suspected parotid gland lesions and differentiation between benign and malignant lesions. Certain conventional MRI features can suggest whether a mass is more likely to be a benign or low-grade malignancy or a high-grade malignancy and adding diffusion-weighted imaging or advanced MRI techniques like perfusion can aid in this distinction. Morphological features seen on MRI, such as low signal on T2-w, infiltrative changes or ill-defined margins, change over time and diffusion restriction can point to the malignant nature of the lesion. MRI is useful for detection and localization of the lesion(s), and associated findings like perineural spread of tumor, lymph node involvement and infiltrative changes of the surrounding tissues. In this pictorial essay, we present selected images of a variety of benign and malignant parotid tumors and emphasize the MRI features that may be useful in their characterization.

MicroRNAs’ Crucial Role in Salivary Gland Cancers’ Onset and Prognosis

Simple Summary

Salivary gland cancers are incredibly heterogeneous, both in the physical onset and in the aggressiveness. Setting up a novel diagnostic and prognostic detection method based on the noninvasive microRNAs’ profiling might represent a goal for the clinical management of those particular malignancies, saving precious time for the patients.

Abstract

Salivary gland cancer (SGC) is an uncommon and heterogeneous disease that accounts for around 8.5% of all head and neck cancers. MicroRNAs (miRNAs) consist of a class of highly conserved, short, single-stranded segments (18–25 nucleotides) of noncoding RNA that represent key gene-transcription regulators in physiological and pathological human conditions. However, their role in SGC development and progression is not completely clear. This review aims to compile and summarize the recent findings on the topic, focusing on the prognostic and diagnostic value of the major modulated and validated microRNAs in SGC. Their differential expression could possibly aid the clinician in delivering an early diagnosis, therapeutic strategy and precision medicine.

Lip pleomorphic adenomas: case series and literature review

BACKGROUND

Pleomorphic adenoma (PA) is the most frequent benign salivary gland tumor, but a lip PA is rare. Although this tumor may be definitively diagnosed by imaging or a tissue biopsy if it is reasonably large, PAs on the lip are relatively small, and they present findings that are similar to those of other lip lesions, which can make a preoperative diagnosis difficult.

METHODS

We analyzed all PAs in the oral region and lesions on the lips treated in our department over the past 20 years, and we discuss them together with the relevant literature.

RESULTS

We found that 11.8% (n=6) of the PAs occurred on a lip (upper lip: 9.8%, lower lip: 2.0%), and ~1% of all mass lesions of the lips were PAs. The average size of the lip PAs was 1.5±0.7 cm (range, 0.7-2.2 cm). For preoperative diagnostic assistance, ultrasonography (US) (n=4), magnetic resonance (MR) (n=3), or no imaging (n=2) was used. An excisional biopsy was performed in all cases, and to date, no recurrence or malignant transformation has been observed.

CONCLUSIONS

Lip PA is relatively rare. Because almost all of these lesions are small, a preoperative diagnosis is more difficult compared to palatal lesions. This tumor is also prone to long-term neglect and has the potential for recurrence and malignant transformation. It is thus necessary to perform an excision that includes the capsule and surrounding tissues, and careful postoperative follow-up should be continued.

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, semi-quantitative 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 semi-quantitative 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.

Metastases to the Parotid Gland: Study from a Tertiary Care Centre

BACKGROUND

Metastases account for 6-25% of parotid tumors, often presenting dilemmas in their diagnosis.

METHODS

Parotid metastases diagnosed on histology/cytology were retrieved. MUC2, MUC5AC, androgen receptor immunohistochemistry was performed in select cases.

RESULTS

Fifty-one samples were identified from 42 patients, including 14 aspirates, 7 biopsies and 30 parotidectomies. Previous history was available in 17 cases, 13 parotidectomies accompanied excision of the primary, and relevant clinical data was unavailable for 12 patients. Majority (81%) had head and neck primaries; eye and ocular adnexa were the commonest subsite (52.4%), and sebaceous carcinoma the commonest histology (33%). When history was unavailable, most metastases were initially diagnosed as poorly differentiated carcinoma/malignant tumor, or mucoepidermoid carcinoma on cytology.

CONCLUSIONS

Intraparotid metastases encompass a wide spectrum, often mimicking primary salivary gland neoplasms, particularly on limited samples. Metastases should be considered when histological/cytological features are unusual; detailed clinical information and ancillary techniques aid in arriving at an accurate diagnosis.

Primary minor salivary gland tumors: A retrospective review of cases seen in a tertiary institution in South East Nigeria

Background

Tumors of the minor salivary glands (MSGs) are rare. They constitute a wide range of histologic types despite their low frequency.

Aim

The aim of this study is to evaluate the clinical and pathological features of 11 different tumors of MSGs presented at the University of Nigeria Teaching Hospital Ituku-Ozalla, Enugu and to compare them with similar studies done elsewhere.

Patients and Method

This is a retrospective study of patients with tumors involving the MSGs seen at the OMFS and ORL clinics, UNTH. Information regarding demographic characteristics, duration at first presentation, types of tumors, site and side affected, and treatment given were recorded in patients' medical records. Data were analyzed using SPSS version 23; qualitative variables were compared using Chi-square test.

Result

One hundred and thirty three cases of various lesions involving the salivary gland were seen within the study period. Fifty three (39.8%) patients met the inclusion criteria and are reported further. Twenty eight (28) cases occurred in males. The mean age of the patients was 39.8 years STD 16.5, while the mean duration of the swellings at presentation was 45.5 months STD 35.4. Pleomorphic adenoma was the most common of the 29 (54.7%) benign histopathologic type seen. The soft palate was the commonest site affected 37 (69.8%). Local excision with wide margin was adequate in treating majority of the swellings 40 (75.5%), while 1 (1.9%) case of recurrence was seen within the study period.

Conclusion

Tumors involving the MSGs are uncommon; males are mostly affected in our environment.

Spindle Cell Lipoma Occurring in the Submandibular Space: Fifth Case Reported along with a Concise Review of the Literature

Spindle cell lipoma (SCL) is an uncommon histological variant of lipoma that accounts for 1.5% of all adipose tumors. It rarely occurs in the oral cavity. The most common sites of involvement are the buccal mucosa, tongue, lip, alveolar mucosa, gingiva, and palate. Submandibular space is a very rare site of occurrence for SCL. When occurs in this site, SCL mainly involves the 4th-7th decade with a female predominance. Due to wide communications of submandibular space, the actual extent and appearance of the lesions present here gets masked up especially those involving the deeper tissues leading to an inaccurate diagnosis. Wide overlap of clinical and histopathological features of SCL to other clinical pathologies leads to a challenging task for the clinicians to reach an accurate diagnosis. To our knowledge, only four cases of intraoral SCL involving the submandibular region directly or indirectly have been reported in the literature. Here we represent another rare case of SCL in an 18-year-old male patient along with a concise review of the literature. This case appears to be quite rare due to its location (submandibular space), age, and sex of the patient (18/M).

Salivary gland tissues and derived primary and metastatic neoplasms: unusual pitfalls in the work-up of sellar lesions. A systematic review

PURPOSE

Salivary gland (SG) tissue and derived neoplasms may occur in the sellar region. As the current literature is mostly limited to case reports, the puzzling case of an inflammatory SG removed by transsphenoidal surgery (TS) and mimicking a prolactinoma prompted us to perform the first systematic review of these unusual conditions.

METHODS

A systematic literature search was conducted according to the PRISMA guidelines. Forty-four individual cases-non-neoplastic enlarged salivary glands (NNESG, n = 15), primary benign (n = 7) and malignant (n = 8) ectopic salivary tumours (ST) and sellar metastasis from eutopic primary ST (n = 14)-were suitable for the analysis of clinical, radiological and pathological characteristics. Therapeutic outcome was reviewed as a secondary endpoint.

RESULTS

All cases were diagnosed after surgery. NNESG commonly affected young and/or female patients, typically leading to headaches and hyperprolactinemia and originating close to the neurohypophysis. Submucosal SG should be excluded before concluding to an intrasellar NNESG after TS. No gender or age predominance was found for primary ectopic ST, which present as large tumors, with histological phenotypes similar to common ST. Hypopituitarism and diabetes insipidus were more frequent in ST than in NNESG. NNESG and benign ectopic ST rarely recur. Malignant ectopic ST should be distinguished from secondary localizations of eutopic ST reaching the sella by contiguity or metastatic spread; both share a frequent unfavorable outcome.

CONCLUSION

Sellar neoplasms derived from SG are rare but misleading conditions and pituitary dysfunction is likely to be more common than currently reported. Appropriate pathological evaluation and multidisciplinary approach are required.

Cytopathology and diagnostics of Warthin's tumour

Warthin's tumour (WT) is a benign epithelial salivary tumour, one type of salivary adenoma. Histologically, WT is structured of two components, epithelial tissue that often lines cystic formations and lymphoid tissue in the tumour stroma. FNA is a reliable diagnostic approach in the diagnosis of salivary gland lesions allowing a highly accurate categorization of benign tumour-like lesions, benign tumours and malignant tumours. In the proposed Milan reporting system of salivary gland lesions, WT is categorized in the IVA group of benign neoplasms. Accurate cytological diagnosis is straightforward when three characteristic components are present: oncocytes, either isolated or associated in clusters, lymphocytes and lymphoid cells and often an inflammatory/necrotic-like substance. Also, specific features of scintigraphy and radiological imaging contribute to the diagnosis of WT. WT is categorized according to Seifert G. et al in 4 types, depending on the proportions of the epithelial component and lymphoid stroma. Differential cytopathological and pathohistological diagnosis include other salivary gland lesions with lymphoid, oncocytic epithelial and cystic components. In some cases, such as the metaplastic WT variant, there are additional cytopathological and histological diagnostic difficulties. Moreover, bilateral, multicentric or multiple and infrequently seen extra-salivary localizations of WT are associated with further cytopathological diagnostic difficulties. Also, a rare possibility of malignant transformation of the epithelial or lymphoid component of WT as well as possible association with other primary tumours remains a challenge in accurate cytopathological and histological diagnosis of WT.

MRI-Based Radiomics to Differentiate between Benign and Malignant Parotid Tumors With External Validation

Background

The differentiation between benign and malignant parotid lesions is crucial to defining the treatment plan, which highly depends on the tumor histology. We aimed to evaluate the role of MRI-based radiomics using both T2-weighted (T2-w) images and Apparent Diffusion Coefficient (ADC) maps in the differentiation of parotid lesions, in order to develop predictive models with an external validation cohort.

Materials and Methods

A sample of 69 untreated parotid lesions was evaluated retrospectively, including 37 benign (of which 13 were Warthin’s tumors) and 32 malignant tumors. The patient population was divided into three groups: benign lesions (24 cases), Warthin’s lesions (13 cases), and malignant lesions (32 cases), which were compared in pairs. First- and second-order features were derived for each lesion. Margins and contrast enhancement patterns (CE) were qualitatively assessed. The model with the final feature set was achieved using the support vector machine binary classification algorithm.

Results

Models for discriminating between Warthin’s and malignant tumors, benign and Warthin’s tumors and benign and malignant tumors had an accuracy of 86.7%, 91.9% and 80.4%, respectively. After the feature selection process, four parameters for each model were used, including histogram-based features from ADC and T2-w images, shape-based features and types of margins and/or CE. Comparable accuracies were obtained after validation with the external cohort.

Conclusions

Radiomic analysis of ADC, T2-w images, and qualitative scores evaluating margins and CE allowed us to obtain good to excellent diagnostic accuracies in differentiating parotid lesions, which were confirmed with an external validation cohort.

Diagnostic value of fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography in sublingual and submandibular salivary gland tumors

The aim of the present study was to compare the diagnostic accuracy of fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT) with that of conventional imaging studies (CIS), such as CT or magnetic resonance imaging (MRI), in the clinical diagnosis and staging of submandibular and sublingual salivary gland tumors. In addition, the data obtained were used to evaluate the significance of maximum standardized uptake value (SUVmax) in diagnosing benign or malignant lesions. For the present study, 18 patients with submandibular or sublingual neoplasms underwent F-18 FDG PET/CT imaging with accompanying CT or MRI. The diagnostic values from 43 F-18 FDG PET/CT scans and 28 CIS of the 18 patients were compared to the gold standard histopathological and/or cytopathological diagnosis. The results demonstrated that the diagnostic accuracy for predicting primary tumors was similar between F-18 FDG PET/CT and CIS. By contrast, PET/CT imaging was more accurate in detecting lymph node metastasis compared with CT or MRI (95.4 vs. 66.7%). F-18 FDG PET/CT had a sensitivity of 88.9% and a specificity of 97.1%, whereas CT or MRI had a sensitivity of 54.5% and a specificity of 75.0%. F-18 FDG PET/CT also enabled screening for distant metastasis, as observed in 10 cases in the present study. Furthermore, there were no significant differences in SUVmax between benign or malignant salivary gland lesions, as high glucose metabolism was also observed in benign tumors. In conclusion, F-18 FDG PET/CT provides more accurate diagnostic information for the evaluation of submandibular and sublingual salivary gland tumors as compared with CIS in terms of lymph node and distant metastasis.

Accuracy of combined quantitative diffusion-weighted MRI and routine contrast-enhanced MRI in discrimination of benign and malignant salivary gland tumors

BACKGROUND

Preoperative imaging of salivary gland tumors is important for predicting and differentiating benign from malignant tumors, and for aiding management planning. We aimed to investigate the accuracy of combined quantitative diffusion-weighted magnetic resonance imaging (MRI) and routine contrast-enhanced MRI in the evaluation of salivary gland tumors and the differentiation of benign from malignant tumors.

RESULTS

This study included 51 patients with a total of 16 benign and 35 malignant lesions that were detected by histopathological analysis. There was a statistically significant difference between the apparent diffusion coefficient values (ADC) of malignant and benign lesions (0.69 ± 0.22 × 10^-3 mm²/s and 1.39 ± 0.52 × 10^-3 mm²/s respectively). The optimal cut-off ADC value was 1.08 with 75% specificity and 97% sensitivity. The routine contrast-enhanced MRI had predicted benign and malignant tumors with 65% sensitivity and 44% specificity. The sensitivity and specificity were greatly increased when quantitative diffusion-weighted MRI was combined with routine contrast-enhanced MRI: 100%, and 88% respectively. A receiver operating curve was generated. The area under curve was 0.88 (p < 0.001, 95% CI: 0.76-0.99).

CONCLUSION

Combined quantitative diffusion-weighted MRI with ADC measurements and routine contrast-enhanced magnetic resonance imaging are helpful tools for the evaluation of salivary gland tumors and help differentiate benign from malignant lesions.

Imaging methods in primary Sjögren's syndrome as potential tools of disease diagnostics and monitoring

Primary Sjögren's syndrome (pSS) is a systemic autoimmune disease that affects exocrine glands, especially salivary and lacrimal glands, leading to their progressive destruction. With highly differentiated clinical course the approach to the definition of pSS is constantly evolving and the pSS classification criteria have been modified over the past years. In the past sialography and scintigraphy were frequently used in pSS diagnostics. Recently no imaging method has been included in the pSS classification criteria. That raises the question about the benefits of using novel imaging techniques such as ultrasonography, elastography and magnetic resonance imaging to diagnose and monitor pSS patients. The purpose of this review is to evaluate the advantages and limitations of widely used imaging methods in pSS and their possible future development.