Update in salivary gland cytopathology: Recent molecular advances and diagnostic applications

Metastases to the parotid glands: An institutional experience

BACKGROUND

Metastatic lesions to the salivary gland are rare and mostly affect the parotids. Metastases represent 8% of all malignant lesions of the parotid gland. Around 80% originate from squamous cell carcinomas (SCC) of the head and neck region. Fine needle aspiration (FNA) plays a crucial role in distinguishing primary salivary gland lesions from metastases. Herein we describe our series of metastases to the parotid glands.

MATERIALS AND METHODS

We analysed 630 parotid gland FNAs over a decade including conventional and liquid-based cytology specimens. Ancillary techniques such as immunocytochemistry (ICC) were conducted on cell blocks.

RESULTS

Eighty (12.4%) cases were malignant lesions, of which 53 (63.75%) were metastases including 24% melanoma, 22.6% SCC, 19% renal carcinomas, 7.5% breast carcinomas, 11.3% lung, 9% intestinal and 1.8% testicular, malignant solitary fibrous tumour and Merkel cell carcinoma. The 53 cases, classified according to the Milan system for salivary cytopathology, belonged to 5 Suspicious for malignancy (SFM) and 48 malignant (M) categories. Forty had a known history of primary malignancy (75.4%), while 13 were suspicious to be a metastatic localisation (24.5%), distributed as 5SFM (2SCC and 3Melanoma) and 8 M. A combination of clinical history, cytomorphology and ICC identified 100% of them.

CONCLUSIONS

Fine needle aspiration plays a central role in the diagnostic workup of patients with metastatic lesions to their parotid glands, thereby defining the correct management. Diagnostic accuracy may be enhanced by applying ICC. Although melanoma and SCC are the most common histological types, several other malignancies may also metastasize to the parotid glands and should be kept into consideration.

Second edition of the Milan System for Reporting Salivary Gland Cytopathology: Refining the role of salivary gland FNA

The use of standardised reporting systems for non-gynaecologic cytopathology has made enormous gains in popularity during the past decade, including for thyroid fine-needle aspiration, urine cytology, serous effusions, pancreas, lymph nodes, lung and more. In February 2018, the first edition of the Atlas of the Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) was published. The MSRSGC defines six diagnostic fine-needle aspiration categories encompassing the spectrum of non-neoplastic, benign and malignant lesions of the salivary glands. The goal of the MSRSGC is to combine each diagnostic category with a defined risk of malignancy and a specific clinical and/or surgical management algorithm. Since its initial publication in 2018, more than 200 studies and commentaries have been published, confirming the role of the MSRSGC. The second edition of the MSRSGC, published in July 2023, includes refined risks of malignancy based on systematic reviews and meta-analyses, a new chapter summarising the use of salivary gland imaging, new advances in ancillary testing and updates in nomenclature.

Second edition of the Milan System for Reporting Salivary Gland Cytopathology: Refining the role of salivary gland FNA

The use of standardized reporting systems for nongynecologic cytopathology has made enormous gains in popularity during the past decade, including for thyroid fine-needle aspiration, urine cytology, serous effusions, pancreas, lymph nodes, lung, and more. In February 2018, the first edition Atlas of the Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) was published. The MSRSGC defines six diagnostic fine-needle aspiration categories encompassing the spectrum of Non-Neoplastic, benign, and malignant lesions of the salivary glands. The goal of the MSRSGC is to combine each diagnostic category with a defined risk of malignancy and a specific clinical and/or surgical management algorithm. Since its initial publication in 2018, more than 200 studies and commentaries have been published confirming the role of the MSRSGC. The second edition of the MSRSGC, published in July 2023, includes refined risks of malignancy based on systematic reviews and meta-analyses, a new chapter summarizing the use of salivary gland imaging, new advances in ancillary testing, and updates in nomenclature. CONCISE SENTENCE: The second edition of the Milan System for Reporting Salivary Gland Cytopathology, published in July 2023, includes refined risks of malignancy based on systematic reviews and meta-analyses, a new chapter summarizing the use of salivary gland imaging, new advances in ancillary testing, updates in nomenclature, and a guide to the practical application of the latest ancillary markers for the diagnosis of selected salivary gland fine-needle aspiration cases.

Second edition of the Milan System for Reporting Salivary Gland Cytopathology: Refining the role of salivary gland FNA

The use of standardized reporting systems for non-gynecologic cytopathology has made enormous gains in popularity during the past decade, including for thyroid fine-needle aspiration, urine cytology, serous effusions, pancreas, lymph nodes, lung, and more. In February 2018, the first edition Atlas of the Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) was published. The MSRSGC defines six diagnostic fine-needle aspiration categories encompassing the spectrum of non-neoplastic, benign, and malignant lesions of the salivary glands. The goal of the MSRSGC is to combine each diagnostic category with a defined risk of malignancy and a specific clinical and/or surgical management algorithm. Since its initial publication in 2018, more than 200 studies and commentaries have been published confirming the role of the MSRSGC. The second edition of the MSRSGC, published in July 2023, includes refined risks of malignancy based on systematic reviews and meta-analyses, a new chapter summarizing the use of salivary gland imaging, new advances in ancillary testing, and updates in nomenclature.

Fine-Needle Aspiration Cytology for Parotid Tumors

Fine-needle aspiration (FNA) cytology is widely used in clinical practice as a simple and minimally invasive test for parotid tumors that allows for preoperative estimation of benignancy and malignancy, histological type, and malignancy grade and can be performed on an outpatient basis. In recent years, cell blocks prepared with core needle biopsy (CNB) and liquid-based cytology (LBC) have increased the reliability of immunostaining and molecular biological testing, leading to improved diagnostic accuracy. In 2018, the Milan System for Reporting Salivary Gland Cytology was introduced, but it does not include malignancy grade or histological type, so we proposed the Osaka Medical College classification as a more clinically based cell classification that includes both types of information, and we have reported on its usefulness. This review gives an overview of the history and use of FNA and describes CNB and LBC and the two classification systems.

Validation of the Milan system for reporting salivary gland cytopathology: a single institution's 10-year experience

INTRODUCTION

Fine needle aspiration cytology is often used for the initial diagnosis and management of patients with salivary gland tumors. Because of its global usage, a consensus classification schema was devised in 2018 to initiate universal reporting of salivary gland cytology specimens, termed the Milan system for reporting salivary gland cytopathology (MSRSGC) and composed of distinct diagnostic categories. Few retrospective studies have been undertaken to review the MSRSGC within institutions.

MATERIALS AND METHODS

We analyzed salivary gland fine needle aspirations during a 10-year span from 2011 to 2021, categorized each cytology case to fit the MSRSGC, and subsequently reviewed the corresponding surgical resections, if indicated, to determine the rate of malignancy (ROM) and rate of neoplasia.

RESULTS

Our ROM was higher (>10%) for the following MSRSGC categories: non-neoplastic, atypia of undetermined significance, and suspicious for malignancy. Also, our data correlated well with the following MSRSGC categories: nondiagnostic, neoplasm-benign, salivary gland neoplasm of uncertain malignant, and malignant.

CONCLUSIONS

Although the data were indicative of the ROM for surgically resected salivary gland lesions, the ROM for non-neoplastic lesions could truly be lower given that most lesions in this category will not undergo surgical resection. Additionally, determination of the rate of neoplasia could a tool that could be used to further guide our clinical colleagues.

Application of the Milan system for reporting salivary gland cytopathology using cell blocks

The Milan system for reporting salivary gland cytopathology (MSRSGC) is a novel standardized classification tool for salivary gland cytology specimens based on the use of direct smears. Formalin-fixed paraffin-embedded (FFPE) cell blocks facilitate the use of ancillary studies, leading to improved diagnostic accuracy. However, the application of the MSRSGC with only cell blocks has not been well established. Consecutive cohort of all parotid gland cytology specimens between 01/01/2018 and 30/06/2021 was performed. All cytology specimens were processed into cell blocks only. Cytologic diagnoses were classified prospectively according to the MSRSGC categories. The risk of malignancy (ROM) for each diagnostic category and the diagnostic performance were calculated. A total of 230 FNA samples from 221 patients were identified, including 47% and 78.4% with surgical or clinical follow-up, respectively. The ROMs based on surgical follow-up for the non-diagnostic, non-neoplastic, AUS, neoplasm: benign, SUMP, SFM and malignant categories were 21.4%,0%,50%,0%,30%,100% and 100%, respectively. The ROMs based on the clinical follow-up for these categories were 7.3%,0%,37.3%,0%,27.3%,100% and 100%, respectively. Following surgical excision, all Milan IVa category samples were confirmed as benign, and all Milan V and VI category samples were confirmed as malignant. This study validates the application of the MSRSGC with the sole use of FFPE cell blocks. The diagnostic accuracy of MSRSGC is high and compares favorably to other institutions using traditional cytology assessment methods. Furthermore, FNA results using this technique enabled to provide optimal patient management based on the ROM of the different Milan system categories.

Knockdown of lncRNA ENST00000603829 Inhibits the Proliferation and Invasion of Salivary Gland Pleomorphic Adenoma through Regulating Cyclin D1

Objective

Salivary gland pleomorphic adenoma (SPA) is a benign neoplasm that can still recur even after radical surgery. To investigate its underlying pathogenesis, here, we examined the significance of lncRNA ENST00000603829 in the proliferation and invasion of SPA.

Methods

SPA tissues (n = 30) and adjacent normal tissues (NC; n = 30) were collected from SPA patients treated at our hospital from June 2017 to December 2019. The human normal salivary gland epithelial cell line (HSG) and SPA cells (PA30, PA37, and PA116) were cultured. qRT-PCR was used for detecting the expression of cyclin D1 and lncRNA ENST00000603829 in tissues and cells. lncRNA ENST00000603829/cyclin D1 was knocked down or overexpressed in PA116 cells. The expression of cyclin D1 and lncRNA ENST00000603829 in different cell lines was examined using qRT-PCR. Transwell assays and cell counting kit-8 (CCK-8) were used to assess cellular invasion and proliferation. The testing result regarding the apoptosis rate and cell cycle was obtained via flow cytometry. Western blot provided the measurement of cyclin D1 expression in cells.

Results

We observed an upregulation of lncRNA ENST00000603829 and cyclin D1 expression in SPA tissues and cells. Knockdown of lncRNA ENST00000603829 inhibited cell invasion and proliferation, promoting apoptosis and retaining the cells during the G0/G1 phase. However, such effects of lncRNA ENST00000603829 knockdown were inhibited when cyclin D1 was overexpressed.

Conclusion

lncRNA ENST00000603829 can promote the occurrence and development of SPA through increasing cyclin D1 expression.

Characterization of tumor-associated MUC1 and its glycans expressed in mucoepidermoid carcinoma

Mucoepidermoid carcinoma (MEC) is one of the most frequently misdiagnosed tumors. Glycans are modulated by malignant transformation. Mucin 1 (MUC1) is a mucin whose expression is upregulated in various tumors, including MEC, and it has previously been investigated as a diagnostic and prognostic tumor marker. The present study aimed to reveal the differences in the mucin glycans between MEC and normal salivary glands (NSGs) to discover novel diagnostic markers. Soluble fractions of salivary gland homogenate prepared from three MEC salivary glands and 7 NSGs were evaluated. Mucins in MEC and NSGs were separated using supported molecular matrix electrophoresis, and stained with Alcian blue and monoclonal antibodies. The glycans of the separated mucins were analyzed by mass spectrometry. MUC1 was found in MEC but not in NSGs, and almost all glycans of MUC1 in MEC were sialylated, whereas the glycans of mucins in NSGs were less sialylated. The core 2 type glycans, (Hex)₂(HexNAc)₂(NeuAc)₁ and (Hex)₂(HexNAc)₂(NeuAc)₂, were found to be significantly abundant glycans of MUC1 in MEC. MEC markedly produced MUC1 modified with sialylated core 2 glycans. These data were obtained from the soluble fractions of salivary gland homogenates. These findings provide a basis for the utilization of MUC1 as a serum diagnostic marker for the preoperative diagnosis of MEC.

Immunocytochemistry for diagnostic cytopathology-A practical guide

Cytological specimens, which are obtained by minimally invasive methods, are an excellent source of diagnostic material. Sometimes they are the only material available for diagnosis as well as for prognostic/predictive markers. When cytomorphology is not straightforward, ancillary tests may be required for a definitive diagnosis to guide clinical management. Immunocytochemistry (ICC) is the most common and practical ancillary tool used to reach a diagnosis when cytomorphology is equivocal, to differentiate entities with overlapping morphological features, and to determine the cell lineage and the site of origin of a metastatic neoplasm. Numerous immunomarkers are available, and some are expressed in multiple neoplasms. To rule out entities within a differential diagnosis, the use of more than one marker, sometimes panels, is necessary. ICC panels for diagnostic purposes should be customised based on the clinical context and cytomorphology, and the markers should be used judiciously to preserve material for additional tests for targeted therapies in the appropriate setting. This review offers a practical guide for the use of ICC for diagnostic cytopathology, covering the most commonly encountered non-hematolymphoid diagnostic scenarios in various body sites.

The effectiveness of the Milan system for risk stratification of salivary gland lesions: The 10-year cytohistopathological correlation results of salivary gland FNA cytology at a tertiary center

BACKGROUND

The Milan system reporting salivary gland cytopathology (MSRSGC) is a tiered classification scheme that is based on risk stratification. The aim of the current study was to assess the risk of malignancy (ROM) and risk of neoplasia (RON) in each of the diagnostic categories proposed by the MSRSGC.

METHODS

A retrospective analysis and categorization according to the MSRSGC was made of salivary gland fine needle aspirations (FNA) performed from January 2007 to December 2017. The FNA cytology results were correlated with subsequent histological follow-up.

RESULTS

A total of 578 FNAs were evaluated and histopathology was available for 198 cases (34.2%). The RON and ROM for individual diagnostic categories were: Non-diagnostic: 52.2% to 13%, non-neoplastic: 21.4% to 10.7%, atypia of undetermined significance: 74% to 22.2%, benign neoplasm: 100% to 1.1%, salivary gland neoplasm of uncertain malignant potential: 93.3% to 53.3%, suspicious for malignancy (SFM): 100% to 100%, and malignant: 100% to 100%. A diagnosis of 'SFM' or 'malignant' with FNA cytology carried a 100% risk for malignancy, while a diagnosis of "non-neoplastic," "benign neoplasm" reduced the probability of malignancy to 3.4%.

CONCLUSION

The MSRSGC is useful for the management of salivary gland lesions as it can successfully differentiate between benign and malignant cases. It will bring uniformity in salivary gland FNA cytology reporting across various institutions globally.

Pediatric Pleomorphic Adenoma of the Palate

Pleomorphic adenoma is the most common salivary gland tumor but is extremely rare in pediatric patients. The parotid gland is the most affected salivary gland, and the minor salivary glands are rarely affected. Here, we report a case of a 12-year-old boy with a pleomorphic adenoma of the palate.

Application of Milan system for reporting of salivary gland pathology and risk stratification: An institutional experience

Background:

Fine-needle aspiration cytology (FNAC) is a sensitive technique for diagnosing salivary gland pathologies. Milan system of reporting salivary gland cytopathology (MSRSGC) is an evidence-based system of reporting which has been introduced to improve reporting and communication between cytopathologist and clinician by introducing standardized categories with specified treatment protocols.

Aims and Objectives:

The aim of the present study is to find the diagnostic accuracy and risk of malignancy (ROM) in various categories when MSRSGC is applied.

Materials and Methods:

A single-institute-based 3-year retrospective study was done. All salivary gland lesions were reclassified according to MSRSGC. ROM, diagnostic specificity, sensitivity and accuracy of FNAC of salivary gland lesions were calculated.

Results:

A total of 133 cases were included in the study. Overall, the most common diagnosis was found to be pleomorphic adenoma comprising 61 (42.8%) of all cases. Adenoid cystic carcinoma was the most commonly diagnosed malignancy comprising of 6 (4.5%) of all lesions. Cases were further divided into Milan categories, namely nondiagnostic, nonneoplastic, atypia of undetermined significance, benign neoplasm, neoplasm of undetermined malignant potential, suspicious of malignancy and malignancy comprising 5 (3.7%), 29 (21.8%), 77 (57.8%), 4 (3%), 3 (2.2%), 1 (0.7%) and 14 (10.5%) cases, respectively, with ROM of 0, 14.28%, 33.33%, 5.71%, 66.66%, 100% and 80%, respectively. Sensitivity, specificity and diagnostic accuracy to separate benign from malignant lesions were 80%, 89.80% and 87.50%, respectively.

Conclusion:

FNAC of the salivary gland lesions is a safe and reliable diagnostic procedure. The Milan system of reporting is a risk stratification system which can improve the overall effectiveness of reporting and care of patients.

A retrospective cytohistological correlation of fine-needle aspiration cytology with classification by the Milan System for Reporting Salivary Gland Cytopathology

Background

Before publication of the new classification system named the Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) in 2018, there was no standard classification for salivary gland lesions obtained by fine-needle aspiration (FNA). We therefore aimed to evaluate the diagnostic utility of this system by retrospectively reviewing FNA samples using the MSRSGC and to determine their risk of developing into neoplasms and becoming malignant.

Methods

Retrospective slide review and classification of salivary gland FNAs obtained over a 6-year period (2013–2018) at a single center were performed by two pathologists. The risks of neoplasm and malignancy for each category also were calculated.

Results

This study surveyed 374 FNAs (371 patients) performed over a six-year period and selected 148 cases that included documented surgical follow-up (39.6%). Among the surgically treated cases, the distributions of FNA categories were as follows: non-diagnostic (ND; 16.9%), non-neoplastic (NN; 2.7%), atypia of undetermined significance (AUS; 3.4%), benign (BN; 54.7%), salivary gland neoplasm of uncertain malignant potential (SUMP; 10.1%), suspicious for malignancy (SM; 6.8%), and malignant (M; 5.4%). The risk of malignancy (ROM) was 24.0% for ND, 0% for NN, 40.0% for AUS, 2.5% for BN, 46.7% for SUMP, 100% for SM, and 87.5% for M. The overall diagnostic accuracy was 95.9% (142/148 cases).

Conclusions

The newly proposed MSRSGC appears to be a reliable system for classification of salivary gland lesions according to the associated ROM.

Salivary Gland FNA Diagnostics in a Real-Life Setting: One-Year-Experiences of the Implementation of the Milan System in a Tertiary Care Center

The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) was introduced in 2018 following other organ specific cytopathological reporting systems and it aimed at bringing a practical, evidence-based, user-friendly classification system with characterization and management algorithms. At the Department of Pathology, Fimlab Laboratories, Tampere, Finland all salivary fine needle aspirations (FNAs) have been given cytopathological diagnoses according to the MSRSGC since January 2018. Analyses of a one-year-period (January 2018–December 2018) consisted of 183 salivary FNA samples from 138 patients with correlation to histopathology in 90 cases with surgical follow-up. The MSRSGC performance in patient based analysis was as follows: accuracy was 90.9%, sensitivity was 61.5%, specificity was 100%, positive predictive value was 100%, and negative predictive value was 89.4%, respectively. Risks of malignancy (ROMs) in MSRSGC categories were: 0.0% (0/15) in non-diagnostic category, 100.0% (1/1) in non-neoplastic category biased by only one falsely-negative lymphoma case, 14.3% (1/7) in atypia of undetermined significance category, 0.0% (0/28) in benign neoplasm category, 27.3% (3/11) in neoplasm of uncertain malignant potential category, and 100% for both suspicious for malignancy (4/4) and malignancy (4/4) categories, respectively. The MSRSGC has been proven as a reliable classification system in salivary gland FNA routine diagnostics in a tertiary care center.

Cytopathological features of secretory carcinoma of salivary glands and ancillary techniques in its diagnostics: impact of new Milan system for reporting salivary gland cytopathology

Secretory carcinoma (SC) of salivary glands is a newly described low-grade malignancy characterized by the presence of ETV6 rearrangement. Only a few cases and very small series with cytomorphology were reported so far. Six cases of fine-needle aspirations (FNAs) from afterward histologically, immunohistochemically and genetically confirmed SCs were retrieved from the archives of the authors. Ancillary immunocytochemistry (ICC) and translocation detection were performed on cell blocks (CBs). All aspirates were sufficiently cellular and cells were arranged in more or less cohesive groups with only mild nuclear polymorphism. The cytoplasm was eosinophilic, granulated and vacuolated, especially in CBs. Secretory material within the microcystic spaces was periodic acid-Schiff (PAS) positive. Triple positivity of immunomarkers S-100 protein, mammaglobin and vimentin was present. The proliferation index was low. Ancillary techniques suggested the possibility of SC in a few cytology cases; nevertheless, the final diagnosis was based on histomorphology, immunohistochemistry and genetics. The SC of salivary glands is detectable pre-operatively using ICC and genetics. The presence of the diagnostic ETV6 rearrangement increases the accuracy of FNA to the maximum. According to the Milan system, cases genetically not confirmed should be categorized as Suspicious for Malignancy or Salivary Gland Neoplasm of Uncertain Malignant Potential (SUMP), both requiring surgery.

Clinically Integrated Molecular Diagnostics in Adenoid Cystic Carcinoma

Adenoid cystic carcinoma is a rare but aggressive type of salivary gland malignancy. This article addresses the need for more effective, biomarker‐informed therapies in rare cancers, focusing on clinical utility and financial sustainability of integrated next‐generation sequencing in routine practice.

Background.

Adenoid cystic carcinoma (ACC) is an aggressive salivary gland malignancy without effective systemic therapies. Delineation of molecular profiles in ACC has led to an increased number of biomarker‐stratified clinical trials; however, the clinical utility and U.S.‐centric financial sustainability of integrated next‐generation sequencing (NGS) in routine practice has, to our knowledge, not been assessed.

Materials and Methods.

In our practice, NGS genotyping was implemented at the discretion of the primary clinician. We combined NGS‐based mutation and fusion detection, with MYB break‐apart fluorescent in situ hybridization (FISH) and MYB immunohistochemistry. Utility was defined as the fraction of patients with tumors harboring alterations that are potentially amenable to targeted therapies. Financial sustainability was assessed using the fraction of global reimbursement.

Results.

Among 181 consecutive ACC cases (2011–2018), prospective genotyping was performed in 11% (n = 20/181; n = 8 nonresectable). Testing identified 5/20 (25%) NOTCH1 aberrations, 6/20 (30%) MYB‐NFIB fusions (all confirmed by FISH), and 2/20 (10%) MYBL1‐NFIB fusions. Overall, these three alterations (MYB/MYBL1/NOTCH1) made up 65% of patients, and this subset had a more aggressive course with significantly shorter progression‐free survival. In 75% (n = 6/8) of nonresectable patients, we detected potentially actionable alterations. Financial analysis of the global charges, including NGS codes, indicated 63% reimbursement, which is in line with national (U.S.‐based) and international levels of reimbursement.

Conclusion.

Prospective routine clinical genotyping in ACC can identify clinically relevant subsets of patients and is approaching financial sustainability. Demonstrating clinical utility and financial sustainability in an orphan disease (ACC) requires a multiyear and multidimensional program.

Implications for Practice.

Delineation of molecular profiles in adenoid cystic carcinoma (ACC) has been accomplished in the research setting; however, the ability to identify relevant patient subsets in clinical practice has not been assessed. This work presents an approach to perform integrated molecular genotyping of patients with ACC with nonresectable, recurrent, or systemic disease. It was determined that 75% of nonresectable patients harbor potentially actionable alterations and that 63% of charges are reimbursed. This report outlines that orphan diseases such as ACC require a multiyear, multidimensional program to demonstrate utility in clinical practice.

Salivary Gland Fine Needle Aspiration and Introduction of the Milan Reporting System

Fine needle aspiration (FNA) is a well-established procedure for the diagnosis and management of salivary gland lesions despite challenges imposed by their diversity, complexity, and cytomorphologic overlap. Until recently, the reporting of salivary gland FNA specimens was inconsistent among different institutions throughout the world, leading to diagnostic confusion among pathologists and clinicians. In 2015, an international group of pathologists initiated the development of an evidence-based tiered classification system for reporting salivary gland FNA specimens designated the "Milan System for Reporting Salivary Gland Cytopathology" (MSRSGC) that culminated with the publication of the MSRSGC Atlas in February 2018. The MSRSGC consists of 6 diagnostic categories, which incorporate the morphologic heterogeneity and overlap among various non-neoplastic, benign, and malignant lesions of the salivary glands. In addition, each diagnostic category is associated with a risk of malignancy and management recommendations. The main goal of the MSRSGC is to improve communication between cytopathologists and treating clinicians, while also facilitating cytologic-histologic correlation, sharing of data from different laboratories for quality control, and research. Herein, we review the current status of salivary gland cytology and the role of MSRSGC in providing a framework for reporting salivary gland lesions.

A microRNA signature for the differential diagnosis of salivary gland tumors

Salivary gland tumors (SGTs) are rare tumors of the head and neck with different clinical behavior. Preoperative diagnosis, based on instrumental and cytologic examinations, is crucial for their correct management. The identification of molecular markers might improve the accuracy of pre-surgical diagnosis helping to plan the proper treatment especially when a definitive diagnosis based only on cytomorphology cannot be achieved. miRNAs appear to be new promising biomarkers in the diagnosis and prognosis of cancer. Studies concerning the useful of miRNA expression in clinical decision-making regarding SGTs remain limited and controversial.The expression of a panel of 798 miRNAs was investigated using Nanostring technology in 14 patients with malignant SGTs (6 mucoepidermoid carcinomas, 4 adenoid cystic carcinomas, 1 acinic cell carcinoma, 1 ductal carcinoma, 1 cystadenocarcinoma and 1 adenocarcinoma) and in 10 patients with benign SGTs (pleomorphic adenomas). The DNA Intelligent Analysis (DIANA)-miRPath v3.0 software was used to determinate the miRNA regulatory roles and to identify the controlled significant Kyoto Encyclopedia of Genes and Genomes (KEGG) molecular pathways. Forty six miRNAs were differentially expressed (False Discovery Rate—FDR<0.05) between malignant and benign SGTs. DIANA miRPath software revealed enriched pathways involved in cancer processes as well as tumorigenesis, cell proliferation, cell growth and survival, tumor suppressor expression, angiogenesis and tumor progression. Interestingly, clustering analysis showed that this signature of 46 miRNAs is able to differentiate the two analyzed groups. We found a correlation between histological diagnosis (benign or malignant) and miRNA expression profile.The molecular signature identified in this study might become an important preoperative diagnostic tool.

Diagnostic utility of fluorescence in situ hybridization testing on cytology cell blocks for the definitive classification of salivary gland neoplasms

INTRODUCTION

Fine needle aspiration biopsy (FNAB) is a minimally invasive modality to evaluate salivary gland neoplasms and help guide clinical management. However, significant overlap in the cytomorphology findings among salivary gland neoplasms often renders the definitive diagnosis challenging. Recently, a number of benign and malignant salivary gland tumors have been characterized by specific chromosomal aberrations detectable using fluorescence in situ hybridization (FISH) testing. In the present study, we evaluated the role of FISH testing performed on cytology cell blocks in the diagnosis of salivary gland neoplasms by FNAB.

MATERIALS AND METHODS

The data from 57 cases of primary salivary gland tumors diagnosed using FNAB at our institution and sent for ancillary FISH testing between 2012 and 2017 were retrospectively reviewed. The FISH studies were performed on cytology cell blocks, and break-apart probes were used to detect characteristic gene rearrangements for PLAG1, MYB, MAML2, and ETV6 for pleomorphic adenoma, adenoid cystic carcinoma, mucoepidermoid carcinoma, and secretory carcinoma (mammary analogue secretory carcinoma), respectively. Of the 57 cases sent for FISH testing, 6 were excluded because of FISH analysis failure (insufficient cell block cellularity).

RESULTS

Of the 51 cases included in the analysis, 15 samples were successfully subclassified after FISH testing, and 10 of these 15 FISH-positive cases were diagnostically confirmed by the surgical pathology review of excision material. Forty cases overall had undergone subsequent excision with the histopathologic follow-up diagnosis available, and all subclassified cases had concordant FNAB, FISH, and excision diagnoses.

CONCLUSIONS

FISH testing performed on cytology cell blocks is a useful adjunct in establishing the diagnosis of salivary gland neoplasms by FNAB.

Risk of high-grade malignancy in parotid gland tumors as classified by the Milan System for Reporting Salivary Gland Cytopathology

BACKGROUND

The Milan System for Reporting Salivary Gland Cytopathology (Milan System) has previously shown its diagnostic utility by categorizing the seven cytology findings in salivary gland lesions. However, there has been lack of study about the risk of high-grade malignancy in the cytology diagnosis based on the Milan System. Thus, we tried to identify the diagnostic ability of the Milan System for high-grade malignancy and to suggest an improved diagnostic approach for preoperative estimation of high-grade malignancy using the Milan System.

METHODS

A total of 413 patients with parotid gland tumors, who had undergone surgical resection from 2011 to 2015 were included in the present study retrospectively. Cytopathology was reclassified according to the Milan System by two independent reviewers. The outcomes were risk of malignancy and risk of high-grade malignancy. The diagnostic performance of the Milan System category [Malignant] for detecting high-grade malignancy was calculated.

RESULTS

The risk of malignancy was 83.3% and 100% in the Milan System categories [Suspicious for Malignancy] and [Malignant], respectively. Meanwhile, the risk of high-grade malignancy was 16.7% and 55.9% in these two categories. Disease-free survival of patients with high-grade malignancy was significantly worse than those with low- and intermediate-grade malignancy. Union combining the Milan System category [Malignant] with the presence of nodal metastasis suggested high-grade malignancy with an acceptable diagnostic sensitivity (0.889-0.963) and negative predictive value (0.900-0.966).

CONCLUSIONS

The Milan System category [Malignant] with the presence of nodal metastasis suggested parotid gland tumors as high-grade malignancy in a pretreatment setting.

Milan System for Reporting Salivary Gland Cytopathology: An Experience with the Implication for Risk of Malignancy

Introduction:

Fine-needle aspiration cytology (FNAC) is a well-established technique for evaluation of salivary gland lesions, but because of the heterogenicity and morphological overlap between spectrum of lesion, there are a few challenges in its wide use. Recently, “The Milan system for reporting salivary gland cytopathology” (MSRSGC) was introduced, providing guide for diagnosis and management according to the risk of malignancy (ROM) in different categories. The current study was conducted retrospectively to reclassify the salivary gland lesions from previous diagnosis and to evaluate the ROM in different categories.

Material and Methods:

Clinical data, FNAC specimen, histological, and clinical follow-up of cases were retrieved, cytological features were re-evaluated, and cases were reclassified as follows: Category 1: Non-diagnostic (ND); Category 2: Non-neoplastic (NN); Category 3: Atypia of undetermined significance (AUS); Category 4a: Neoplasm: benign (NB), Category 4b: Neoplasm: salivary gland neoplasm of uncertain malignant potential (SUMP); Category 5: suspicious of malignancy (SM); and Category 6: Malignant (M).

Result:

Total 293 cases were evaluated cytologically, and histological follow-up was available in 172 cases. The distribution of cases into different categories was as follows ND (6.1%), NN (38.2%), AUS (2.7%), NB (33.4%), SUMP (2.0%), SM (2.4%), and M (15%). Overall, ROM reported were 25%, 5%, 20%, 4.4%, 33.3%, 85.7%, and 97.5%, respectively for each category. Overall, sensitivity was 83.33%, specificity was 98.31%, positive predictive value was 95.74%, and negative predictive value was 92.80%.

Conclusion:

MSRSGC is a recently proposed six category scheme, which places salivary gland FNAC into well-defined categories that limit the possibilities of false negative and false positive cases.

Risk stratification of salivary gland cytology utilizing the Milan system of classification

BACKGROUND

The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) is based on risk stratification. Our study is a retrospective review of salivary gland fine needle aspiration cytology (FNAC) with the goal of determining the risk of malignancy (ROM) in each of the categories proposed by the MSRSGC.

METHODS

FNAC of salivary gland lesions with corresponding surgical resection specimens were retrieved over a 5-year period. Metastatic tumors were excluded. BothFNAC and corresponding surgical resections were reviewed blindly and classified as per criteria published by the MSRSGC. The ROM for each of the diagnostic categories was determined and compared with the ROM published by the MSRSGC.

RESULTS

The total number of entities and ROM in 199 reviewed cases were as follows: Nondiagnostic 18 (9.2%) (ROM 0%), non-neoplastic 4(2%) (ROM 0%), atypia of undetermined significance (AUS) 12(6%) (ROM 33%), benign neoplasm 118(59.2%) (ROM 0.8%), salivary gland neoplasm of uncertain malignant potential (SUMP) 22(11%) (ROM 40.9%), suspicious for malignancy 3(1.5%) (ROM 100%), malignant 22(11%) (ROM 100%).

CONCLUSION

The ROM reported in our study was mostly concordant with ROM published by the MSRSGC. This classification is helpful for the management of categories; nondiagnostic, non-neoplastic, benign neoplasm, suspicious for malignancy and malignant. The management is not standardized for the category, salivary gland neoplasm of uncertain malignant potential, as clinical information plays an important role in planning surgical procedures at an individual basis. Further studies will need to be performed using this new classification to help define appropriate management and predict ROM more accurately.

Liquid-based cytology versus conventional cytology in fine-needle aspirates of salivary gland neoplasms

Background

Liquid-based cytology (LBC) is a method of retrieving and processing of cytological material for the assessment of both gynecological and nongynecological cases introduced in 1996. Mostly conventional smears (CS) are prepared in Indian scenario; however, due to increasing popularity of LBC in nongynecology specimens, LBC is also used in few centers for diagnosing salivary gland neoplasm.

Aim

The aim of this study is to compare CS and LBC in fine-needle aspiration cytology (FNAC) of the salivary gland neoplasms in terms of cytomorphological details, adequacy, ease of interpretation, pitfalls, and diagnostic efficiency.

Materials and Methods

We conducted a prospective, observational, comparative study which included 64 salivary gland neoplasms. Both CS and LBC (SurePath) were prepared as per standard protocols and examined.

Results and Conclusion

In our study, specificity and positive predictive value of both the techniques (conventional and LBC) were found to be 100%. Sensitivity of both the techniques was found to be similar (66.7%). Negative predictive value and diagnostic accuracy of conventional technique were found to be almost similar to that of LBC technique (97.6% vs. 97.2% and 97.7% vs. 97.4%). In terms of adequacy and cellularity, CSs were better than LBC. Ease of interpretation was better with CSs due to abundant chondromyxoid stroma, an important clue in the diagnosis of pleomorphic adenoma. Nuclear details and background were better in LBC as compared to CS. Hence, we conclude that in salivary gland FNAC, both CS and LBC have similar diagnostic efficiency. however, interpretation of conventional smears is easier than Liquid Based Cytology especially in cases of pleomorphic adenoma. However, some advantages of LBC in respect to conventional cytology, with better-preserved morphology obtained from LBC becomes furthermore obligatory.

Updates on Immunohistochemical and Molecular Markers in Selected Head and Neck Diagnostic Problems

CONTEXT

- The head and neck regions have complex anatomic structures. They are not exempted from the rare occurrences of highly unusual, diagnostically challenging malignant neoplasms and mimickers.

OBJECTIVE

- To review and update the utility of immunohistochemistry and molecular biomarkers and to pursue diagnostic accuracy on selected rare neoplasms, especially some poorly differentiated malignancies.

DATA SOURCES

- Personal experience and information from the literature.

CONCLUSIONS

- Head and neck tumors include neoplasms originating from heterogeneous tissue. Using the selected clinical cases, this review illustrates a continuous development of emerging molecular-genetic techniques to assist in the interpretation of uncommon, often poorly differentiated, highly malignant neoplasms. The diagnostic results are appropriately transmitted to the oncologists, radiation oncologists, and surgeons to create a coordinated plan of care for patients with these unusual disorders affecting the head and neck.

Three-year cytohistological correlation of salivary gland FNA cytology at a tertiary center with the application of the Milan system for risk stratification

BACKGROUND

Fine-needle aspiration (FNA) cytology of salivary glands is a well-established technique that plays a critical role in the preoperative diagnosis of lesions. A risk stratification of FNA diagnostic categories has been recently proposed to be useful in reporting. The aims of this study were to evaluate the diagnostic accuracy of salivary gland FNA and to apply the proposed Milan system for reporting salivary gland lesions.

METHODS

A retrospective audit of FNA specimens of salivary gland lesions reported from 2014 to 2016 was performed. A correlation with the follow-up histopathology, wherever it was available, was performed. The aspirates were then categorized according to the Milan system as follows: nondiagnostic, nonneoplastic, atypical, benign neoplasm, neoplasm of uncertain malignant potential (NUMP), suspicious for malignancy, or positive for malignancy. Furthermore, the risk of malignancy and the risk of high-grade malignancy were calculated for all diagnostic categories.

RESULTS

A total of 631 salivary gland aspirates were evaluated: 2.2% were nondiagnostic, 55.8% indicated nonneoplastic lesions, and 40.4% indicated neoplastic lesions. Histopathology was available for 94 cases (14.9%). FNA had a sensitivity of 79.4% and a specificity of 98.3% with an overall diagnostic accuracy of 91.4% for differentiating malignant tumors from benign tumors. The overall risk of malignancy was 17.4% for the nonneoplastic category, 100% for the atypical category, 7.3% for the benign neoplasm category, 50% for the NUMP category, and 96% for the positive-for-malignancy category.

CONCLUSIONS

Salivary gland FNA continues to have high diagnostic accuracy and is thus helpful for guiding management. Neoplasms with classic cytomorphology are easily diagnosed; however, in difficult cases showing overlapping features, the use of the Milan system could be beneficial. Cancer Cytopathol 2017;125:767-75. © 2017 American Cancer Society.

The Milan System for Reporting Salivary Gland Cytopathology: Analysis and suggestions of initial survey

BACKGROUND

An international panel of experts in the field of salivary gland cytology (SGC), supported by the American Society of Cytopathology (ASC) and the International Academy of Cytology, conducted a survey to seek evidence and practice patterns regarding SGC. Results were used to provide focus for the proposed Milan System for Reporting Salivary Gland Cytopathology.

METHODS

The study group, formed during the 2015 European Congress of Cytology held in Milan, Italy, generated a survey that included 49 specific questions related to the taxonomies, practices, and diagnostic entities of salivary cytology. Qualtrics software was used as the study platform. Software and server support were provided by the division of information technology at the University of Wisconsin. The survey was available online from November 2015 until February 2016. Participants were invited through the Web sites of the ASC, the International Academy of Cytology, and the Papanicolaou Society of Cytopathology as well as by the ASC e-mail "ListServe"; responses were evaluated by the Milan System editors.

RESULTS

Responses from a total of 515 participants were collected and reviewed. A total of 347 participants provided demographic data information. Responses revealed variations in diagnostic practice and subsequent management. Participants believed that the acceptable rate for nondiagnostic samples should not be higher than 10%. There were varied opinions regarding the approach to neoplastic lesions of uncertain malignant potential, those that may or may have not local invasion and distant spread.

CONCLUSIONS

Results of the survey demonstrated strong support for the development of a unified system for reporting SGC. Cancer Cytopathol 2017;125:757-66. © 2017 American Cancer Society.

Cytology of Primary Salivary Gland-Type Tumors of the Lower Respiratory Tract: Report of 15 Cases and Review of the Literature

Primary pulmonary salivary gland-type tumors are rare neoplasms arising from the seromucinous submucosal glands of the lower respiratory tract (LRT), the most common of which are mucoepidermoid carcinoma (MEC) and adenoid cystic carcinoma. They are morphologically indistinguishable from their salivary gland counterpart and recognizing them is a challenge, especially on cytological specimens. We analyzed 15 cases of histologically proven primary salivary gland tumors of the LRT to identify cytomorphological features and define potential diagnostic clues that might assist cytopathologists in the preoperative diagnosis of these neoplasias. Three out of the four cases of adenoid cystic carcinomas showed the characteristic tridimensional cell clusters and hyaline globules, whereas the last one did not show malignant cells; only two cases of MEC presented the three characteristic cell types (i.e., squamous, intermediate, and mucin secreting) on cytology. Since these neoplasms are rare and do not have a completely specific set of cytological features, it is important for practicing cytopathologists to be aware of the possibility of encountering them, in specimens from patients with LRT masses, in order to render the correct diagnosis.

PLAG1: An Immunohistochemical Marker with Limited Utility in Separating Pleomorphic Adenoma from Other Basaloid Salivary Gland Tumors

OBJECTIVE

Fine-needle aspiration (FNA) diagnosis of salivary gland neoplasms is often challenging. Differentiating between pleomorphic adenomas (PA) and other basaloid neoplasms, especially basal cell adenoma (BCA) and adenoid cystic carcinoma (AdCC), can be difficult in cellular aspirates. PLAG1 (PA gene 1) is a proto-oncogene, which is frequently rearranged in PAs, leading to the aberrant expression of its protein. PLAG1 IHC expression has been reported to be positive in most PAs. The aim of this study was to evaluate the sensitivity and specificity of PLAG1 to differentiate PA from other basaloid neoplasms.

STUDY DESIGN

Immunohistochemical evaluation of PLAG1 was performed on 125 cases (52 FNAs and 73 surgical excisions). Nuclear staining of tumor cells was scored by the intensity and percentage of positive tumor cells. A combined score of >5 was defined as positive.

RESULTS AND CONCLUSION

The sensitivity (55%) and specificity (75%) of PLAG1 in diagnosing PA in FNAs is relatively modest thus limiting its diagnostic utility. BCAs and AdCCs showed PLAG1 false positivity, in surgical excision specimens and less so in FNAs. This may be due to limited sampling or tumor heterogeneity. Hence, PLAG1 is a modest marker for PAs in FNAs.

Fine-Needle Aspiration Biopsy of Salivary Gland Lesions

CONTEXT

Fine-needle aspiration (FNA) is a well-established diagnostic approach for salivary gland lesions; however, lack of a standard system of terminology for classification of salivary gland neoplasms collected by FNA and the relatively high frequency of uncertainty of diagnosis are likely partly responsible for current confusion in the interpretation of these FNA samples.

OBJECTIVE

To propose a novel classification system for reporting salivary gland FNA samples and summarize recent progress in application of molecular and immunohistochemical markers in selected salivary gland neoplasms.

DATA SOURCES

Literature review and authors' personal practice experience.

CONCLUSIONS

The new classification system provides a more succinct, standardized interpretation of results and will ultimately assist in communication between clinicians, clinical decision making, and preoperative patient counseling. Impressive advances have been made in recent years in the understanding of molecular pathogenesis of salivary gland tumors. With the newly acquired diagnostic tools, significant improvement in diagnostic accuracy of salivary gland FNA can certainly be expected.

Cytogenetic and immunohistochemical biomarker profiling of therapy-relevant factors in salivary gland carcinomas

OBJECTIVES

There is currently no established algorithm for the molecular profiling of therapy-relevant defects in salivary gland carcinomas (SGC). HER2 overexpression in a subfraction of SGC and low frequencies of EGFR mutations are known. Here, we established receptor and cell signalling profiles of 17 therapy-relevant factors and propose a molecular diagnostic algorithm for SGC.

MATERIALS AND METHODS

Formalin-fixed and paraffin-embedded tissue samples from SGC (n = 38) were analysed with immunohistochemistry and fluorescence in situ hybridisation (FISH).

RESULTS

Two or more expressed receptors and/or receptor gene amplification were detectable in eight of 38 (21%) tumours: HER2 3+/AR 1+, HER3 gene amplification/AR 1+/EGFR 1+, ER 3+/AR 1+, EGFR 2+/PR 1+ and EGFR 2+/PR 1+/AR 1+. No FGFR1-3, MET, ALK1, ROS1, RET, BRAF nor VEGFA defects were detectable, and ERCC1 was not overexpressed. No PD1+ tumour-infiltrating T cells were detectable.

CONCLUSION

Personalised therapy of patients with salivary gland carcinomas should include HER2 and EGFR signalling testing and, in negative cases, evaluation of rare potential target molecules. ERCC1 and PD1 do not appear to be reliable markers for the decision for or against chemotherapy or immunotherapy, respectively.