Use of fluorescent in-situ hybridisation in salivary gland cytology: A powerful diagnostic tool

Molecular testing in salivary gland cytopathology: A practical overview in conjunction with the Milan system

Recently, significant advances in the molecular characterization of salivary gland neoplasms have facilitated the classification and diagnosis of specific diagnostic entities. In the highly challenging diagnostic scenario of salivary malignancies, molecular testing is increasingly being adopted in routine practice to refine the cytological diagnosis of salivary lesions. Here, we reviewed the most recent evidence in the field of salivary glands molecular cytopathology.

Cytopathological analysis of salivary gland cancer: REFCOR recommendations by the formal consensus method

OBJECTIVE

To determine the indications for fine-needle cytology and the modalities of frozen section pathological analysis in the management of salivary gland cancer.

MATERIAL AND METHODS

The French Network of Rare Head and Neck Tumors (REFCOR) formed a steering group who drafted a narrative review of the literature published on Medline and proposed recommendations. The level of adherence to the recommendations was then assessed by a rating group according to the formal consensus method.

RESULTS

Fine-needle cytology is recommended as part of the diagnostic work-up for a major salivary gland tumor suspicious for malignancy. Fine-needle cytology should be performed after MRI to avoid artifacts. Frozen section analysis is recommended to confirm the malignant nature of the tumor, to adapt the extent of resection and to indicate neck dissection. Whenever possible, the entire tumor and adjacent salivary or periglandular tissue should be sent for frozen section analysis.

CONCLUSION

Fine-needle cytology and frozen section analysis play an essential role in the management of salivary gland cancers.

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.

Efficacy of Fine-Needle Aspiration Cytology in Diagnosing Secretory Carcinoma of Salivary Gland: A Systematic Review and Meta-Analysis

INTRODUCTION

The diagnosis of salivary gland secretory carcinoma (SC) in fine-needle aspiration specimens is challenging because its low-grade nature makes it difficult to differentiate it from various benign or malignant salivary gland neoplasms. Currently, the gold standard is demonstration of ETV6-NTRK3 fusion gene. However, the decision for ordering this costly molecular testing can be facilitated by the correct recognition of its cytomorphological features. The aim of the review was to determine the accuracy of fine-needle aspiration cytology (FNAC) in diagnosis of salivary gland SC. The secondary objective was to recognize varied cytomorphological patterns, characteristic features of SC and differentiate it from other neoplasms.

METHODS

PubMed/MEDLINE, Science Direct, Embase, Cochrane review, and PROSPERO databases were searched for studies having the following key search terms: ("secretory carcinoma of salivary gland" OR "mammary analogue secretory carcinoma of salivary gland") AND ("Cytology" OR "Cytological features" OR "aspirate" OR "cytodiagnosis") published in the time frame of 2010 to June 2023. Studies reporting cytological features of the salivary gland tumors which were confirmed/diagnosed as SC on molecular investigation, were included in the systematic review. Finally, seventeen studies reporting a total of 45 cases were included in the metanalysis.

RESULTS

The sensitivity of the FNAC in diagnosing SC in salivary gland is 27.7% (95% CI: 16.6-42.5%). The LR+ (positive likelihood ratio) was 0.654 (0.344-1.245), LR- (negative likelihood ratio) was 1.023 (0.538-1.946), and diagnostic odds ratio was 0.421 (0.129-1.374). The molecular testing and/or immunohistochemistry performed on cell block increased the diagnostic accuracy.

CONCLUSION

Recognition of subtle cytomorphological patterns, i.e., papillary formation, clusters, and singly dispersed cells along with presence of fine intracytoplasmic vacuolations were the characteristic findings in majority of cases, confirmed with diagnostic molecular profiling. This may be helpful in identification of this rare entity with limited published literature and help in increasing diagnostic accuracy.

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.

Molecular testing of cytology specimens: overview of assay selection with focus on lung, salivary gland, and thyroid testing

Ancillary and molecular testing of cytopathology specimens has emerged as a reliable and useful tool to provide diagnostic information and treatment-related biomarker status for the management of cancer patients. The cytology specimens obtained through minimally invasive means have proven suitable testing substrates for a variety of ancillary tests, including immunohistochemistry, fluorescence in situ hybridization, as well as polymerase chain reaction and next generation sequencing molecular techniques. By focusing specifically on the cytology specimen, this review provides an overview of basic testing considerations and assay selection in addition to updates on the ancillary testing of cytologic tumor specimens from the lung, salivary gland, and thyroid.

Epithelial-Myoepithelial Carcinoma of the Minor Salivary Glands: Case Series with Comprehensive Review

Epithelial-myoepithelial carcinoma (EMC) is a rare salivary gland tumor that is histologically characterized by biphasic tubular structures composed of inner ductal and outer clear myoepithelial cells, which is especially uncommon in the minor salivary glands (MSG). Because of its histologic variety, complexity, and heterogeneity, it is sometimes challenging to make the accurate diagnosis. Here, we report a literature review of EMC of the MSGs with our experience of two cases. Incisional biopsy was suggestive of pleomorphic adenoma in Case 1 and pleomorphic adenoma or a low-grade salivary gland carcinoma in Case 2. Both cases were performed intraoral tumor resection, and they have good postoperative courses and are alive with no evidence of local recurrence or metastasis at 31 and 16 months, respectively. Considering that the anatomy, structure, and size of salivary glands are quite different from MSGs, it might be difficult to predict EMCs of the MSG similarly to EMCs of the major salivary glands. This comprehensive review also reports the features of EMC of the MSG cases and the trends of diagnosis and discusses treatment strategy.

Diagnostic challenges in the gray-zone lesions of fine-needle aspiration cytology

Fine-needle aspiration cytology (FNAC) is an excellent technique for rapid diagnosis due to its speed, accuracy, and cost-effectiveness. However, there are many gray-zone areas in cytology that needs attention. These lesions in the aspiration cytology can be overcome by applying the selective use of the series of tests. This review discusses the diagnostic challenges in the gray-zone areas in FNAC. It emphasizes the use of selective ancillary techniques to solve the problems in this area.

An Overview on the Histogenesis and Morphogenesis of Salivary Gland Neoplasms and Evolving Diagnostic Approaches

Simple Summary

Diagnosing salivary gland neoplasms (SGN) remain a challenge, given their underlying biological nature and overlapping features. Evolving techniques in molecular pathology have uncovered genetic mutations resulting in these tumors. This review delves into the molecular etiopatho-genesis of SGN, highlighting advanced diagnostic protocols that may facilitate the identification and therapy of a variety of SGN.

Abstract

Salivary gland neoplasms (SGN) remain a diagnostic dilemma due to their heterogenic complex behavior. Their diverse histomorphological appearance is attributed to the underlying cellular mechanisms and differentiation into various histopathological subtypes with overlapping fea-tures. Diagnostic tools such as fine needle aspiration biopsy, computerized tomography, magnetic resonance imaging, and positron emission tomography help evaluate the structure and assess the staging of SGN. Advances in molecular pathology have uncovered genetic patterns and oncogenes by immunohistochemistry, fluorescent in situ hybridization, and next–generation sequencing, that may potentially contribute to innovating diagnostic approaches in identifying various SGN. Surgical resection is the principal treatment for most SGN. Other modalities such as radiotherapy, chemotherapy, targeted therapy (agents like tyrosine kinase inhibitors, monoclonal antibodies, and proteasome inhibitors), and potential hormone therapy may be applied, depending on the clinical behaviors, histopathologic grading, tumor stage and location, and the extent of tissue invasion. This review delves into the molecular pathways of salivary gland tumorigenesis, highlighting recent diagnostic protocols that may facilitate the identification and management of SGN.

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.

Evaluation of NR4A3 immunohistochemistry (IHC) and fluorescence in situ hybridization and comparison with DOG1 IHC for FNA diagnosis of acinic cell carcinoma

BACKGROUND

Acinic cell carcinoma (AcCC) is diagnostically challenging on fine-needle aspiration because it can mimic several other neoplasms or even normal acinar tissue. Immunopositivity for DOG1, especially circumferential membranous staining, can support the diagnosis of AcCC but is not entirely specific, and it is prone to technical and interpretive challenges on small specimens. NR4A3 (nuclear receptor subfamily 4 group A member 3) translocation and nuclear NR4A3 overexpression were recently described in the majority of AcCCs. Here, the authors evaluate the performance of NR4A3 immunohistochemistry (IHC) and NR4A3 break-apart fluorescence in situ hybridization (FISH) on cell block preparations and compare them with DOG1 IHC in distinguishing AcCC from other entities in the differential diagnosis.

METHODS

The authors identified 34 cytology cell blocks with lesional cells, including 11 specimens of AcCC (2 of which derived from 1 patient and showed high-grade transformation) as well as 2 secretory carcinomas, 7 salivary duct carcinomas, 4 mucoepidermoid carcinomas, 3 oncocytomas, 3 renal cell carcinomas, and 6 specimens containing nonneoplastic salivary gland tissue. NR4A3 IHC, DOG1 IHC, and NR4A3 FISH were attempted for all cases.

RESULTS

NR4A3 IHC had 81.8% sensitivity and 100% specificity for AcCC, whereas NR4A3 FISH had 36.4% sensitivity and 100% specificity, although 4 cases (3 mucoepidermoid carcinomas and 1 salivary gland tissue sample) could not be analyzed because of low cellularity. Notably, no normal acinar tissue specimens showed NR4A3 positivity by IHC or FISH. In addition, DOG1 IHC had 72.7% sensitivity and 92% specificity.

CONCLUSIONS

NR4A3 IHC is highly specific for the diagnosis of AcCC and is more sensitive than DOG1 IHC and NR4A3 FISH. In addition, NR4A3 IHC performance is not improved by the inclusion of DOG1 IHC. Finally, NR4A3 positivity resolves the perennial problem of distinguishing AcCC from normal acinar tissue.

Preoperative evaluation and treatment consideration of parotid gland tumors

BACKGROUND

The nature of parotid tumors often remains unknown preoperatively and final histopathology may reveal unexpected malignancy. Still, the use of fine-needle aspiration cytology (FNAC) and imaging varies in the management of these tumors.

METHODS

We evaluated the preoperative examinations and management of all 195 parotid gland tumors diagnosed within our catchment area of 1.6 million people during 2015.

RESULTS

Altogether 171 (88%) tumors were classified as true salivary gland neoplasms. FNAC showed no false malignant findings, but it was false benign in 5 (2.6%) cases. Preoperative MRI was utilized in 48 patients (25%). Twenty (10%) malignancies included 16 salivary gland carcinomas. Pleomorphic adenomas accounted for 52% of all adenomas. For 24 (40%) Warthin tumors, surgery was omitted.

CONCLUSION

The proportion of malignancies was lower than generally presented. Our proposed guidelines include ultrasound-guided FNAC with certain limitations. MRI is warranted in selected cases, but seems unnecessary routinely.

A 4-Year Retrospective Analysis of Salivary Gland Cytopathology Using the Milan System for Reporting Salivary Gland Cytology and Ancillary Studies

The cytopathology of salivary glands presents major challenges due to the heterogeneity of benign and malignant neoplasms, which is reflected in the large range of WHO 2017 Classifications. Fine needle aspiration (FNA) of salivary gland tumours is still the favoured initial approach as it results in good sensitivity and specificity. The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) was published in 2018 and comprises seven categories. We report results from a 4-year retrospective analysis of 328 salivary gland FNAs which were reviewed and classified according to the MSRSGC. We assess the risk of neoplasm, the risk of malignancy and the contribution of ancillary studies to the diagnosis. Benign neoplasms were the most frequent diagnosis (44.2%). Malignant and suspicious for malignancy were identified in 11.3% and 4.9% of diagnosed cases, respectively. Histopathological analysis after surgery was available for 216 (65.8%) of the cases. All malignant cases were confirmed post-surgery, and 68.8% of suspicious for malignancy were confirmed as malignant tumours. Immunocytochemistry was informative in 72.3% of cases. Immunocytochemistry and FISH provided the definitive diagnosis in 23.7% and 33% of cases, respectively. In conclusion, the MSRSGC is more effective when specific features of neoplasms can be identified. Ancillary studies help to further characterise salivary gland tumours and thereby increase the accuracy of MSRSGC.

Ancillary testing in salivary gland cytology: A practical guide

Salivary gland cytology is challenging, and historically the role of ancillary testing has been limited. However, numerous molecular/genetic advances in the understanding of salivary gland neoplasms during the last decade have facilitated the development of many useful diagnostic markers, such as PLAG1 and HMGA2 immunohistochemistry for pleomorphic adenoma and ETV6 fluorescence in situ hybridization for secretory carcinoma. Numerous salivary gland neoplasms are characterized by specific molecular/genetic alterations, many of which can be identified on cytologic preparations by karyotype analysis, fluorescence in situ hybridization, or immunohistochemical surrogates. Next-generation sequencing also has potential diagnostic applications, although to the authors' knowledge it currently has no routine role in salivary cytology. The primary goal of salivary fine-needle aspiration (FNA) is to facilitate appropriate clinical management. Ancillary testing has greatly enhanced the ability for accurate classification as per The Milan System for Reporting Salivary Gland Cytopathology and allows for the definitive diagnosis of many salivary FNA specimens, and also may resolve diagnostic uncertainty for FNAs that may be classified in The Milan System for Reporting Salivary Gland Cytopathology categories of salivary gland neoplasm of uncertain malignant potential or suspicious for malignancy. This review provides an updated discussion of the molecular/genetic features of the more commonly encountered salivary neoplasms by FNA, and discusses the application of available diagnostic immunohistochemical and molecular tests in salivary gland cytology.

[WHO classification of head and neck tumours 2017: Main novelties and update of diagnostic methods]

The publication of the new WHO classification of head and neck tumours in 2017 brought major modifications. Especially, a new chapter is dedicated to the oropharynx, focusing on the description of squamous cell carcinoma induced by the virus Human Papilloma Virus (HPV), and new entities of tumors are described in nasal cavities and sinuses. In this article are presented the novelties and main changes of this new classification, as well as the updates of the diagnostic methods (immunohistochemistry, cytogenetics or molecular biology).

Synchronous Parotid (Mammary Analog) Secretory Carcinoma and Acinic Cell Carcinoma: Report of a Case

Mammary analogue secretory carcinoma (MASC) is a recently described low-grade salivary gland malignancy with histologic, immunohistochemical and molecular similarities to secretory carcinoma of the breast, including a specific t(12;15)(p13;q25) resulting in an ETV6-NTRK3 gene fusion. Ultrasound and magnetic resonance imaging frequently document a macrocystic structure. The main differential diagnosis of secretory carcinoma is with low grade acinic cell carcinoma (AciCC). The two can be differentiated with immunohistochemical stains for S100, mammaglobin, carbonic anhydrase VI and DOG-1; the identification of the specific translocation can help to characterize non-typical cases. We report a unique case of synchronous MASC and AciCC presenting in a parotid gland and discuss the implications of the correct identification of the two tumors.