Impact on clinical follow-up of the Milan System for salivary gland cytology: A comparison with a traditional diagnostic classification

Update on Salivary Gland Fine-Needle Aspiration and the Milan System for Reporting Salivary Gland Cytopathology

CONTEXT.—

Fine-needle aspiration (FNA) is a well-established procedure for the diagnosis and management of salivary gland lesions, despite challenges imposed by salivary gland tumor 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, the Milan System for Reporting Salivary Gland Cytopathology (MSRSGC). The MSRSGC consists of 6 diagnostic categories, which incorporate the morphologic heterogeneity and overlap among various nonneoplastic, benign, and malignant lesions of the salivary glands. In addition, each MSRSGC diagnostic category is associated with a risk of malignancy and management recommendations.

OBJECTIVE.—

To review the current status of salivary gland FNA, core needle biopsies, ancillary studies, and the beneficial role of the MSRSGC in providing a framework for reporting salivary gland lesions and guiding clinical management.

DATA SOURCES.—

Literature review and personal institutional experience.

CONCLUSIONS.—

The main goal of the MSRSGC is to improve communication between cytopathologists and treating clinicians, while also facilitating cytologic-histologic correlation, quality improvement, and research. Since its implementation, the MSRSGC has gained international acceptance as a tool to improve reporting standards and consistency in this complex diagnostic area, and it has been endorsed by the 2021 American Society of Clinical Oncology management guidelines for salivary gland cancer. The large amount of data from published studies using MSRSGC served as a basis for the recent update of the MSRSGC.

Salivary Gland Fine-Needle Aspiration: The Current and Future Landscape

Fine-needle aspiration represents a valid tool for the diagnosis/management of salivary gland lesions. The past years assessed the lack of uniform diagnostic reports for salivary cytopathology leading to interpretative issues. In 2015, an international group of cytopathologists developed an evidence-based tiered classification system for reporting salivary gland fine-needle aspiration (FNA) specimens, the "Milan System for Reporting Salivary Gland Cytopathology" (MSRSGC). The present landscape of salivary cytology is represented by the growing adoption of the MSRSGC and the assessment of its diagnostic role. The future landscape is characterized by the increasing role of ancillary techniques for diagnostic and prognostic purposes.

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.

Comparison Study of FNAC Using the Milan System Cytopathology versus Definitive Histology for the Diagnosis of Salivary Gland Tumors

INTRODUCTION

Salivary gland tumors (SGT) represent 6 to 8 percent of head and neck tumors. The cytologic diagnosis of SGT is performed by fine-needle aspiration cytology (FNAC) with variable sensitivity and specificity. The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) categorizes the cytological results and provides the risk of malignancy (ROM). The aim of our study was to evaluate the cytological findings with the definitive pathological findings to assess the sensitivity, specificity, and diagnostic accuracy of FNAC in SGT according to MSRSGC classification.

METHOD

An observational, retrospective, single-center study was carried out at a tertiary referral hospital over a period of 10 years. Patients that underwent FNAC for major SGT and that have undergone surgery to remove the tumor were included. A histopathological follow-up was performed on the surgically excised lesions. Results from the FNAC were categorized into one of the six MSRSGC categories. The sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy of FNAC for determining benign and malignant cases were calculated.

RESULTS

A total of 417 cases were analyzed. The cytological prediction of ROM was 10% in nondiagnostic, 12.12% in non-neoplastic, 3.58% in neoplasm benign group, 60% in AUS and SUMP groups, and 100% in suspicious and malignant group. The statistical analysis of sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy for determining benign cases was 99%, 55%, 94%, 93%, and 94%, respectively, and for determining malignant neoplasm was 54%, 99%, 93%, 94%, and 94%, respectively.

CONCLUSION

In our hands, MSRSGC is highly sensitive for benign tumors and highly specific for malignant tumors. The low sensitivity to differentiate malignant from benign cases makes it necessary to apply an adequate anamnesis, physical examination, and imaging tests to consider surgical treatment in most cases.

Assessment of Risk of Malignancy of Fine-needle Aspiration Cytology in Salivary Gland Lesions Using the Milan System for Reporting Salivary Gland Cytopathology Categorization: A Systematic Review and Meta-analysis

BACKGROUND

Fine-needle aspiration cytology (FNAC) of the salivary gland is crucial in the identification of salivary gland lesions, but the variation in morphological pattern and the overlap of morphological traits can result in erroneous interpretation and affect treatment, making FNAC of the salivary gland problematic. The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) was created to address these problems.

OBJECTIVES

To ascertain whether the FNAC method using MSRSGC was reliable in predicting the risk of malignancy (ROM) in each category of salivary gland lesions.

MATERIALS AND METHODS

The databases PubMed-MEDLINE, Web of Science, Cochrane, Scopus, and Google Scholar were all searched using pertinent keywords, reference searches, and citation searches. A fixed effect model was used to determine the pooled proportion with a 95% confidence interval (CI). All statistical analyses were performed using Meta Disc and R version 4.0.2 (R Foundation for Statistical Computing).

RESULTS

After reviewing the submissions' abstracts and titles, 58 documents that satisfied the necessary inclusion and exclusion criteria were ultimately selected. A total of 19,652 samples from 19,408 individuals was analyzed, out of which 9,958 samples were available for histopathological follow-up. The pooled ROM for category I was 10%, category II was 5%, category III was 28%, category IV A was 2%, Category IV B was 34%, category V was 91%, and category VI was 99%.

CONCLUSION

Milan System for Reporting Salivary Gland Cytopathology is useful for risk stratification and quality control, confirming its validity and diagnostic utility. Widespread use of MSRSGC would improve the accuracy of salivary gland cytology and lead to better patient care and improved treatment strategies. The results of this study are in consonance with reported values as per MSRSGC except for category V.

CLINICAL SIGNIFICANCE

The MSRSGC which was first reported in 2018 is a very useful tool for proper stratification of ROM in salivary gland FNAC. This study allowed us to validate the ROM values in different categories as reported in MSRSGC.

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.

The Milan System for Reporting Salivary Gland Cytopathology

OBJECTIVES

Our study assesses whether the Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) offers any benefit over the original cytology classification, and measures interobserver agreement.

METHODS

Four cytopathologists retrospectively blindly classified preoperative cytology by MSRSGC from 101 resected salivary tumors. Consensus MSRSGC diagnoses were correlated with surgical pathology diagnoses and compared with the original cytology classification. Diagnostic parameters were calculated for both systems. Interobserver variability was assessed.

RESULTS

The original cytology classification vs MSRSGC had sensitivity, specificity, positive predictive value, and negative predictive value of 75.0% vs 78.3%, 97.1% vs 98.0%, 91.2% vs 94.7%, and 90.1% vs 90.0%, respectively. The original cytology classification risk of neoplasm (RON) was 91.7% for "negative for malignancy" and 100.0% for other categories. The MSRSGC RON was 71.4% in category II (nonneoplastic) and 100.0% in all other categories. The original cytology classification risk of malignancy (ROM) ranged from 0.0% for "atypical" to 100.0% for "positive for malignancy." The MSRSGC ROM ranged from 0.0% in categories I (nondiagnostic) and III (nonneoplastic) to 100.0% in category VI (malignant). Weighted agreement using the MSRSGC was 92% (Gwet AC1, 0.84); unweighted agreement was 69% (Gwet AC1, 0.64). MSRSGC category IVA (benign neoplasm) was most likely to show interobserver agreement, with complete agreement in 67% of cases.

CONCLUSIONS

The MSRSGC performs similarly to the original cytology classification and shows relatively high interobserver agreement.

Nondiagnostic salivary gland FNAs are associated with decreased risk of malignancy compared with "all-comer" patients: Analysis of the Milan System for Reporting Salivary Gland Cytopathology with a focus on Milan I: Nondiagnostic

BACKGROUND

The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) reports a 25% rate of malignancy (ROM) for the Milan I: Nondiagnostic (ND) category. We clarify the ROM of ND salivary gland fine-needle aspirations (SGFNAs) based on our institutional experience and review of the literature.

METHODS

Overall risk of malignancy (OROM) and that for those with surgical/flow cytometric follow-up (FROM) for each category and "all-comers" were calculated for Emory SGFNAs from January 2010 through March 2021. From a literature review of 50 articles using MSRSGC, distribution of diagnoses, rates of follow-up, FROM, and OROM by category were calculated. FROMs and OROMs between ND FNAs and all-comers were compared. Milan I rate was compared with the ratio of Milan I OROM to all-comer OROM.

RESULTS

Of 819 SGFNAs at Emory, 12.8% (n = 105/819) were ND. Thirty-two had known follow-up, with 12 (37.5%) being malignant. Nonmucinous cyst contents accounted for 26.7% of ND SGFNAs (n = 28/105); all 7 with surgical follow-up were benign. Of 50 MSRSGC studies, 18.2% (n = 2384/13,129) of SGFNAs were classified as ND, 26.6% (n = 635/2384) with known follow-up. Total FROM and OROM for ND FNAs (15.7% and 4.1%, respectively) were significantly lower than those for all-comers (24.9% and 11.4%, respectively) (p < .001). There was no relationship between rate of ND SGFNA and ND ROM.

CONCLUSIONS

The ND category is associated with a lower ROM than that of all-comer SGFNA patients. The "true" ROM for ND SGFNAs is likely best estimated by the 4.1% OROM. SGFNAs showing nonmucinous cyst contents have a particularly low ROM. Rate of ND SGFNAs does not influence ND ROM.

Fine-Needle Aspiration Cytology of Salivary Gland Tumors Before the Milan System: Ten Years of Experience at a Tertiary Care Center in Turkey

Objective

The role of fine-needle aspiration cytology (FNAC) is well established for preoperative evaluation of patients with salivary gland lesions. However, the lack of a uniform system for salivary gland FNAC has limited its effectiveness. In recent years, the Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) has been in use around the world to report the cytology results. We aimed to investigate the efficacy and accuracy of FNAC examined according to pre-MSRSGC era dichotomous benign/malignant classification in salivary gland tumors.

Methods

Patients who underwent surgery between January 2011 and December 2020 due to major salivary gland tumors were retrospectively analyzed. Two hundred and four patients were included in the analysis. Preoperative FNAC results and final histopatological diagnoses were grouped as benign or malignant. Final histopatological diagnoses were compared with the preoperative FNAC results. Also, sensitivity, specificity, and accuracy of the preoperative FNAC results, as well as the agreement between both tests were investigated.

Results

The sensitivity, specificity, accuracy, positive and negative predictive values of the preoperative FNAC for the diagnosis of malignancy were 59.09%, 97.85%, 93.75%, 76.47%, and 95.29%, respectively. There was a moderate agreement between the preoperative FNAC results and final histopatological diagnoses.

Conclusion

The accuracy of the preoperative FNAC and the information given about malignancy risk are the most important criteria for patient management and decision-making. The MSRSGC, which consists of a six-tiered classification rather than a dichotomous "yes/no" system, may contribute to patient management and decision-making by increasing the efficacy and accuracy of FNAC.

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.

The Milan System for Reporting Salivary Gland Cytopathology: An outcome of retrospective application to three years' cytology data of a tertiary care hospital

Objectives:

Fine-needle aspiration cytology (FNAC) of the salivary gland lesions has diverse and sometimes overlapping features that pose a diagnostic challenge for the cytopathologists. The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) has been introduced to bring uniformity in the reporting of salivary gland FNAC and improve the clinic-pathologic communication resulting in better patient management. The aim of the present study was to assess the application of the MSRSGC on FNAC specimens of salivary gland lesions at a tertiary care hospital.

Material and Methods:

All salivary gland aspiration cytology cases along with histopathology follow-up of salivary gland lesions, wherever available, over a period of 36 months were analyzed and re-categorized according to MSRSGC into six categories and the risk of malignancy (ROM) was computed.

Results:

Of the 123 patients, 23 (18.69%) were classified as non-diagnostic, 39 cases (31.7%) as non-neoplastic, one (0.81%) as atypia of undetermined significance (AUS), benign neoplasm in 49 (39.8%) cases, uncertain malignant potential in two cases (1.63%), suspicious of malignancy in two cases, and malignant in seven cases (5.69%). Out of 123 cases, histopathological correlation was available in 34 cases, for which the ROM was calculated. The ROM was 0% for non-neoplastic, 11.1% for benign neoplasm, and 100% each for salivary neoplasm of uncertain neoplastic potential, and 100% for malignant categories.

Conclusion:

In the present study, the distribution of cases according to MSRSGC was comparable with the previous studies. The proportion of cases classified as AUS was within the goal set by MSRSGC at less than 10%. A risk-based stratification of salivary gland lesions in the form of MSRSGC is essential in the present era to guide and alert the clinician about the subsequent management plan and convey the ROM.

Histopathologic and clinical outcomes of Milan System categories "non-diagnostic" and "non-neoplastic" of salivary gland fine needle aspirations

INTRODUCTION

The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) specifies six categories with estimated risks of malignancy (ROM) and suggested management. The estimated ROM is 25% for Non-Diagnostic (ND) category, and 10% for Non-Neoplastic (NN). This study aimed to investigate histopathologic and clinical outcomes of MSRSGC categories ND and NN at the authors' institution.

MATERIALS AND METHODS

Cytopathology fine needle aspiration reports from 2008-2020 were searched for the word "salivary", "parotid", and "submandibular". Cases fitting Non-Diagnostic (ND) and Non-Neoplastic (NN) categories were identified. Follow-up cyto-/histopathologic and clinical data were extracted.

RESULTS

There were 43 ND and 46 NN cases. The average age was 58.3 years. Neoplastic lesions were found in 13 of 43 (30%) ND and 3 of 46 (6.5%) NN. The rate of malignancy in ND category was 14.0% (6/43) and 0% (0/46) in NN category. Four cases in ND (9.3%) and 6 (13.0%) in NN had no neoplasm and instead had an underlying reactive condition (e.g., chronic sialadenitis) or inflammatory lesion (e.g., lymphoepithelial cyst) on histologic follow-up. There was no follow-up pathology in 46.5% NDs (20/43) and 82.6% NNs (38/46); however, no lesions were apparent clinically with a mean follow-up of 3 years and 1.5 years, respectively.

CONCLUSIONS

MSRSGC categories ND and NN are helpful for reporting salivary gland FNA results. With proper clinical and radiologic correlation, ROM of NN is low; however, ROM of ND remains significant. Repeat FNA after correlation for ND cases seems prudent as neoplasms and malignancies may have gone undetected.

Contribution of small tissue biopsy and flow cytometry to preoperative cytological categorization of salivary gland fine needle aspirates according to the Milan System: Single center experience on 287 cases

BACKGROUND

Milan system for reporting salivary gland cytopathology (MSRSGC) was proposed to provide a standardized reporting system for salivary gland fine needle aspiration biopsies. Modified Menghini type semi-automatic aspiration biopsy needles provide small tissue fragments (STFs), as well as cellular smears, and immunohistochemical and molecular studies can be performed using the STFs.

AIMS

We aimed to evaluate the contribution of STFs and ancillary techniques to pre-operative diagnosis of salivary gland lesions.

MATERIALS AND METHODS

In this study, smears of 287 cases with histopathological correlation were re-reviewed and assigned to one of the MSRSGC categories. In the second step, histopathological and immunohistochemical findings in STFs were evaluated together with cytological findings. Final diagnoses were obtained with the inclusion of flow cytometry (FC) results when available. Risk of malignancy (ROM) was calculated for each diagnostic category.

RESULTS

In the evaluation based on smears, a specific diagnosis could be obtained in 64.8% of the cases. ROMs were 0% for nondiagnostic (ND), 5.6% for non-neoplastic (NN), 55% for atypia of undetermined significance (AUS), 0.6% for benign neoplasm (BN), 27.8% for salivary gland neoplasm of uncertain malignant potential (SUMP), and 100% for suspicious for malignancy (SFM) and malignant (M) categories. With the addition of histopathological and immunohistochemical findings and FC results, a specific diagnosis could be obtained in 75.2% of the cases. ROMs were 0% for ND, 4.5% for NN, 53.8% for AUS, 0.6% for BN, 0% for SUMP, and 100% for SFM/M categories.

CONCLUSIONS

STFs contribute correct categorization of salivary gland lesions. The major contribution of ancillary methods is in the SUMP category.

The Milan System for Reporting Salivary Gland Cytopathology: Assessment of Cytohistological Concordance and Risk of Malignancy

INTRODUCTION

The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) was proposed by the American Society of Cytopathology and the International Academy of Cytology to bring uniformity in the reporting system and the treatment protocol. A wide range of risk of malignancy for each category has been reported by various authors by applying the system.

AIM

We intend to study the cytohistological concordance and the ROM for each of the diagnostic categories of the Milan system.

MATERIALS AND METHODS

The study included 292 cases of fine-needle aspiration cytology (FNAC) of salivary gland lesions over a period of 3 years. The diagnosis of these cases was reclassified into the 6 categories of the Milan system. The cytohistological concordance and ROM for each category of the Milan system were calculated based on the clinical and histopathological follow-up.

RESULTS

The patients' age ranged from 3 to 81 years with the mean of 42.65 ± 16.3 years. The cases included 189 (64.7%) parotid, 82 (28.1%) submandibular, and 21 (7.2%) cases of minor salivary gland swellings. Follow-up histopathological diagnosis for 102 cases was available. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were calculated to be 64.28, 97.01, 90, 86.67, and 87.37%, respectively. After reclassification, the number of cases in each category was as follows: category I: 31 (10.62%), category II: 80 (27.4%), category III: 2 (0.68%), category IVA: 143 (48.97%), category IVB: 1 (0.34%), category V: 13 (4.45%), and category VI: 22 (7.53%). The calculated ROM was as follows: category I: 42.86%, category II: 26.67%, category III: 100% category IVA: 10.17%, category IVB: 0%, category V: 71.42%, category VI: 100%.

CONCLUSION

FNAC is an excellent procedure to differentiate benign from malignant tumors, and MSRSGC is a useful system for risk assessment and deciding the further treatment protocol. Our findings also suggest that in addition to the surgical follow-up, inclusion of the clinical and radiological follow-up may be a better strategy for calculation of ROM, especially for categories I and II.

Application of the Milan System for Reporting Salivary Gland Cytopathology: Experience of an academic institution in a tertiary academic medical center

BACKGROUND

The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) represents a standardized reporting system for salivary gland lesions. The recent literature has demonstrated a wide range of data regarding range of malignancy (ROM) and interobserver variability. The objective of the current study was to evaluate the reproducibility and interobserver agreement of MSRSGC, and establish the ROM in a unique patient population residing within a designated Health Professional Shortage Area.

METHODS

A total of 380 salivary gland fine-needle aspiration cases were obtained over a 3-year period. Corresponding cytology reports and slides were reviewed in a blinded fashion by a panel of cytopathologists and recategorized using MSRSGC. ROM was calculated by cytohistologic correlation in 176 cases. Agreement between review of reports and slides and interobserver reliability were determined using kappa statistics.

RESULTS

The ROMs per MSRSGC category based on review of reports and slides were as follows: 4% and 0%, respectively, for nonneoplastic; 22% and 0%, respectively, for nondiagnostic; 42.9% and 48%, respectively, for atypia of undetermined significance; 1.6% and 1.9%, respectively, for benign-neoplastic; 17.9% and 15.6%, respectively, for salivary gland neoplasm of uncertain malignant potential; 81.8% and 71.4%, respectively, for suspicious for malignancy; and 100% and 90.5%, respectively, for malignant. There was a 59.2% overall agreement between review of reports and slides with regard to recategorizing salivary gland lesions (kappa, 0.51). The interobserver reliability demonstrated a 64.6% agreement (weighted kappa, 0.59).

CONCLUSIONS

The ROMs at the study institution appeared comparable to those in the published literature. There was moderate overall agreement among cytopathologists and low interobserver agreement with regard to the indeterminate categories. Image-guided fine-needle aspiration specimens; rapid onsite adequacy; and integration of clinical, imaging, and ancillary studies can improve diagnostic accuracy among indeterminate lesions.

The Milan system for reporting salivary gland cytopathology: A comprehensive review of the literature

BACKGROUND

The Milan system for Reporting Salivary Gland Cytopathology (MSRSGC) was published in 2018. Since then, many authors have published their institutional experience by retrospectively assigning salivary gland fine-needle aspiration cases to each of the MSRSGC categories and calculated their risk of malignancy (ROM) accordingly.

METHODS

We reviewed all published articles available online in English that used the MSRSGC since or near its publication. We calculated the risk of neoplasm and ROM for each diagnostic category. In addition, the false-negative and false-positive rates from all studies were examined.

RESULTS

Thirty-seven articles were identified in the English literature; 2 were published in 2017, 14 in 2018, 18 in 2019, and 3 in 2020. The total number of cases was 16 394, and 8 468 had surgical follow-up. The mean ROM was 16.9% for category I, 10.5% for category II, 39.3% for category III, 2.9% for category IVa, 39.4% for category IVb, 84.2% for category V, and 97.5% for category VI. The mean false-negative rate for MSRSGC categories II and IVa was 4.5%. Similarly, the mean false-positive rate for MSRSGC categories V and VI was 5.1%.

CONCLUSION

A tiered classification scheme of MSRSGC is helpful in effectively guiding clinical management of patients with salivary gland lesions. The reported mean ROM for each category in most studies is within the recommended range published by the MSRSGC.

The Milan system for reporting salivary gland cytopathology: Single center experience with cell blocks

BACKGROUND

Salivary gland fine needle aspiration (FNA) has a well-established role in the evaluation of salivary gland lesions. The Milan system for reporting salivary gland cytopathology (MSRSGC) was developed in 2018 to accomplish a standardized reporting across institutions. This classification is predominantly based on the use of direct smears. This single center study aims to evaluate and further validate the MSRSGC based on the sole use of cell blocks and carry out a risk assessment based on follow up histopathology.

METHODS

A total of 359 FNA specimens from 343 patients processed as cell blocks between 2012 and 2018 were retrieved, with histologic follow-up available in 235 cases. The cytological diagnosis were reclassified according to the MSRSGC categories: non-diagnostic, non-neoplastic, atypia of undetermined significance (AUS), benign neoplasm, salivary gland neoplasm of uncertain malignant potential (SUMP), suspicious for malignancy (SFM), and malignant. The use of ancillary immunohistochemistry or molecular testing was recorded. The risk of malignancy (ROM) was calculated for each diagnostic category.

RESULTS

Overall accuracy, sensitivity, specificity, positive predictive value, and negative predictive value were 92.9%, 75.9%, 97.9%, 91.7%, and 95%, respectively. The ROM for the non-diagnostic, non-neoplastic, AUS benign neoplasms, SUMP, SFM and malignant categories were 13.8%, 14.2%, 30%, 6.3%, 20.8%, 60%, and 100%, respectively.

CONCLUSION

This large single center retrospective series further validates the MSRSGC. The proposed diagnostic classification is reproducible with use of cell blocks. Discrepancies in number of cases per category and ROM are based on cross-institution variabilities, pre-FNA diagnostics (imaging) and ancillary tests.

Retrospective application of the Milan System for reporting salivary gland cytopathology: A Cancer Center experience

BACKGROUND

The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) was recently proposed. Herein, we retrospectively applied this nomenclature system to salivary gland lesions sampled by ultrasound-guided fine-needle aspiration (FNA).

METHODS

All cases of salivary gland FNA with available surgical follow-up, in the period from 2014 to 2017 at our institution were reviewed and reclassified according to one of the six categories of the MSRSGC, blind to the surgical outcome. Overall sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated, as well as risks of neoplasm (RON) and risk of malignancy (ROM) for each of the proposed categories.

RESULTS

There were 104 salivary gland lesions, with a female predominance (57.7%), most cases from the parotid gland (89.4%). Mean age was 53.2 years. Distribution of the specimens according to the Milan System was as follows: 19.2% nondiagnostic (ND), 8.7% non-neoplastic (NN), 9.6% atypia of undetermined significance (AUS), 40.4% benign neoplasm (BN), 14.4% salivary gland neoplasm of uncertain malignant potential (SUMP), 1.9% suspicious for malignancy (SFM), and 5.8% malignant. Sensitivity, specificity, PPV, and NPV using MSRSGC were calculated as 75%, 98.4%, 88.9%, and 95.3%, respectively. RON/ROM for each category were 60%/15% for ND, 44.4%/0% for NN, 90%/40% for AUS, 100%/9.5% for BN, 100%/13.3% for SUMP, 50%/50% for SFM and 100%/100% for malignant.

CONCLUSION

The use of the Milan System proved to be a useful method to predict the risk of neoplasm and malignancy in the sample studied, with high sensitivity and specificity.

A retrospective comparison of salivary gland fine needle aspiration reporting with the Milan system for reporting salivary gland cytology

BACKGROUND

Fine needle aspiration (FNA) is a routine sampling method in the diagnostic work up of salivary gland lesions. Despite universal use, no standardised classification existed for the cytopathological reporting of such entities until recently. The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) aims to standardise the reporting of these lesions, offering risk of malignancy rates and clinical management recommendations.

METHODS

We retrospectively applied MSRSGC to cases reported over a 5-year period. Salivary FNA specimens were reclassified according to the MSRSGC as (I) non-diagnostic, (II) non-neoplastic, (III) atypia of undetermined significance (AUS), (IV) benign neoplasm and salivary gland neoplasm of uncertain malignant potential, (V) suspicious for malignancy, and (VI) malignant. Cases with surgical resections were documented and risk of malignancy calculated for each group, where possible. We compared our outcomes with similar studies performed since publication of the Milan criteria.

RESULTS

In total, 192 specimens were reassigned as non-diagnostic (n = 30), non-neoplastic (n = 31), AUS (n = 1), benign neoplasm (n = 97) and salivary gland neoplasm of uncertain malignant potential (n = 4), suspicious for malignancy (n = 3), and malignant (n = 26). There were 73 surgical resections. Our calculated risk of malignancy was within the proposed MSRSGC rates for the non-diagnostic, benign neoplasm and malignant groups. One AUS case did not undergo surgery. Benign and malignant sensitivities and specificities for the original reporting categories were 88.24% and 95.72%, and 100% and 95.45% for the MSRSGC, respectively.

CONCLUSION

Salivary gland FNA has high diagnostic accuracy and the MSRSGC offers standardised reporting and assistance in the stratification of cases. This may improve communication between pathologists and clinicians with improved outcomes for patients.

The role of fine-needle aspiration biopsy (FNAB) in the diagnostic management of parotid gland masses with emphasis on potential pitfalls

PURPOSE

The treatment strategy of parotid gland tumours depends mainly on the histopathological type of the lesion. Fine-needle aspiration biopsy (FNAB) is recommended in preoperative diagnostics. The aim of the study was to evaluate the FNAB standing in the diagnostic algorithm of parotid gland lesions and to correlate FNAB results in relation to the definitive histopathological diagnosis.

MATERIAL AND METHODS

The retrospective analyses of 651 examined and consequently surgically treated parotid gland lesions at the Department of Otorhinolaryngology and Head and Neck Surgery, 1st Faculty of Medicine, Charles University in Prague between 2006 and 2016 were used. Preoperative cytological results were consequently evaluated in relation to the definitive histopathological diagnosis.

RESULTS

The cohort consisted of 367 women and 284 men (average age 58 years). FNAB was diagnostic in 604 (92.8%) patients and non-diagnostic in 47 (7.2%) patients. The result of FNAB was positive (suspicious for malignant tumour) in 89 (14.7%) patients and negative (benign) in 515 (85.3%) patients. Sensitivity of the examination was 80.00%, specificity was 93.82%, PPV 62.92%, NPV 97.28%, and LR + and LR- were 12.95 and 0.21, respectively, with an accuracy of 92.22%.

CONCLUSION

Our results confirm the significant role of FNAB in the diagnostic algorithm of parotid gland lesions.

The Milan system for reporting salivary gland cytology: A retrospective analysis of 1384 cases in a tertiary Southeast Asian institution

BACKGROUND

The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) aims to provide a common language for risk stratification and management. We examine the incidence of MSRSGC categories and the corresponding risk of malignancy (ROM) within a tertiary referral centre in Southeast Asia.

METHODS

Salivary gland fine needle aspirations (FNAs) performed within a 10-year period were classified retrospectively according to the MSRSGC. Cytohistologic correlation was performed. The results were compared with the existing literature, including Asian and Western studies.

RESULTS

A total of 1384 salivary gland FNAs were evaluated, 421 with corresponding histology. The category distribution was: nondiagnostic, 28.9%; nonneoplastic, 18.0%; atypia of undetermined significance (AUS), 9.8%; benign neoplasm, 32.9%; salivary gland neoplasm of uncertain malignant potential (SUMP), 5.7%; suspicious for malignancy, 1.6%; and malignant, 3.2%. The ROMs were: nondiagnostic, 10.0%; nonneoplastic, 17.5%; AUS, 29.5%; benign neoplasm, 0.5%; SUMP, 17.1%; suspicious for malignancy, 83.3%; and malignant, 100.0%. Our relatively high nondiagnostic rate likely reflects preanalytical factors, whereas our low malignancy rate may be related to population and health care accessibility. Our nonneoplastic ROM was 17.5% compared with 5% to 10% in the literature, likely due to the relatively small number of excised cases; the ROM for SUMP was 17.1% versus 21% to 44% in the literature, possibly reflecting a significant proportion of benign basaloid neoplasms on histology. Interestingly, all false-negative cases in the nonneoplastic category were lymphoid-rich lesions.

CONCLUSION

This is one of the largest single-institution studies in the existing literature documenting both the incidence and ROMs of MSRSGC categories. We also highlight specific challenges surrounding lymphoid-rich lesions.

Evaluation of Accuracy of Milan System for Reporting Salivary Gland Cytology: Review of Morphology and Diagnostic Challenges in Each Category

Background:

Fine-needle aspiration cytology (FNAC) in salivary gland lesions is challenging for the cytopathologists due to diverse morphological pattern and overlapping morphologic features which are responsible for the pitfalls. The present study was conducted to evaluate the efficacy of the Milan system in the diagnosis of salivary gland lesions and to discuss and review the morphology and diagnostic challenges in individual Milan categories.

Materials and Methods:

The study was a retrospective diagnostic analytical study in the department of pathology at a tertiary care hospital attached to medical college over a duration of 2 years. All the salivary gland FNAC cases were reviewed and divided into six categories as per the proposed Milan system for reporting salivary gland cytopathology. Histopathology correlation was performed wherever possible.

Results:

A total of 131 cases formed the study group. The number of cases in each category were: nondiagnostic 4.5%, nonneoplastic 51.9%, atypical lesions 0.76%, neoplastic category benign neoplasm 21.37%, salivary lesion of uncertain malignant potential 1.52%, suspicious category 2.29%, and malignant category 17.5%. The risk of malignancy for each categories were 6.25% (nonneoplastic), 100% (atypical), 3.3% (neoplastic), 0% (benign), 25% (salivary neoplasm of uncertain neoplastic potential), 100% (suspicious for malignancy), and 100% (malignant) categories. Sensitivity, specificity, positive predictive value, and negative predictive value of FNAC with application of Milan system was 89.4%, 100%, 100%, and 95.74%, respectively.

Conclusion:

The high efficacy of FNAC obtained in the present study, when Milan system was applied, confirms the usefulness of this scheme in reporting salivary gland lesions.

The Milan System at Memorial Sloan Kettering: Utility of the categorization system for in-house salivary gland fine-needle aspiration cytology at a comprehensive cancer center

BACKGROUND

The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) provides a standardized reporting system for salivary gland fine-needle aspiration (SGFNA). We review the clinical utility of the MSRSGC at a tertiary care cancer center by assessing the rates of malignancy (ROM) among different categories.

METHODS

A retrospective search was performed to retrieve all SGFNA cases performed at our institution between 1/1/07 and 12/31/18. The initial primary diagnoses were recorded and cases were then assigned to appropriate MSRSGC categories. ROM was then calculated for all categories.

RESULTS

A total of 976 cases were identified, and 373 with follow-up. The ROM was 19.7% (192/976) for all-comers and 51.3% (192/374) among cases with follow-up. Using MSRSGC, SGFNA showed a sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 65.6%, 87.4%, 100%, and 72.6%, respectively. ROM for MSRSGC categories I, II, III, IVa, IVb, V, and VI were 20.7%, 30.0%, 45.8%, 3.3%, 50.7%, 100%, and 100%, respectively. Utilizing MSRSGC resulted in a nondiagnostic rate of 14.4%. The nondiagnostic rate was lower when the procedure was performed by pathologists vs nonpathologists (12.9% vs 15.8%) but was comparable when rapid on site evaluation (ROSE) was performed (12.9% vs 11.6%).

CONCLUSION

In our patient population, MSRSGC resulted in a perfect PPV and moderate NPV. Utilizing MSRSGC results in a higher nondiagnostic rate due to the inclusion of cases with benign elements or cyst contents only in this category. Performing ROSE is more important in attaining an adequate sample than the specialty of the person performing SGFNA.

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.

Mucoepidermoid carcinoma, acinic cell carcinoma, and adenoid cystic carcinoma on fine-needle aspiration biopsy and The Milan System: an international multi-institutional study

BACKGROUND

We evaluated the diagnostic accuracy (DA), risk of neoplasm (RON), and risk of malignancy (ROM) for the commonly encountered malignant salivary gland tumors mucoepidermoid carcinoma (MECa), acinic cell carcinoma (ACCa), and adenoid cystic carcinoma (ADCa) applying The Milan System for Reporting Salivary Gland Cytology (MSRSGC).

MATERIALS AND METHODS

The cytology archives from 2007 to 2017 of 9 academic institutions were searched for salivary gland FNAs for the following key words mentioned either in the principal and/or differential diagnosis: MEC, ACCa, and ADCa. The original cytology diagnosis was retrospectively classified according to the MSRSGC. Patient demographics, biopsy site, and available surgical follow-up were recorded. The final analysis included only cases with surgical follow-up.

RESULTS

A total of 212 salivary gland FNAs were included. Based on retrospective reclassification according to MSRSGC, 97 of 212 (46%) FNA cases carried a diagnosis of malignancy specific for either MECa, ACCa, or ADCa. In the remaining 115 cases, 24 of 212 (11%) were reclassified as suspicious for malignancy (SM) and 91 of 212 (43%) as salivary gland neoplasm of uncertain malignant potential (SUMP). The DA for MECa, ACCa, and ADCa was 78.7%, 75% and 89%, respectively. The RON was 100% for all 3 tumors and the ROM was 93.6% for MECa, 96.8% for ACCa, and 94.4% for ADCa.

CONCLUSIONS

The DA of 78.7% for MECa, 75% for ACCa, and 89% for ADCa is reasonable in FNA specimens. Although the management of definitive cases of malignancy remains unchanged, the MSRSGC provides a ROM for SM and SUMP categories, which can improve patient management.

Application of the Milan System for Reporting Salivary Gland Cytopathology: A retrospective study in a tertiary institute

BACKGROUND

Fine needle aspiration (FNA) cytology has been widely used in the preoperative evaluation of salivary gland lesions. The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) is a tiered risk-stratification scheme designed to standardize reporting and facilitate decision making. We aimed to clarify the validity and diagnostic utility of the MSRSGC-based classification of salivary gland lesions.

METHODS

A total of 1020 salivary gland FNA specimens were retrieved between 2008 and 2017, with histologic follow-up data available for 349 specimens. Within the present retrospective study, each specimen with follow-up data was reclassified according to the MSRSGC diagnostic categories: nondiagnostic, nonneoplastic, atypia of undetermined significance (AUS), benign neoplasm, salivary gland neoplasm of uncertain malignant potential (SUMP), suspicious for malignancy (SM), and malignant. The risk of malignancy (ROM) was calculated based on the histologic follow-up data.

RESULTS

The diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of the MSRSGC-based classification of the malignant potential of salivary gland lesions were 80.1%, 70.4%, 99.2%, 90.5%, and 96.7%, respectively. The ROM calculated for specimens assigned to the nondiagnostic, nonneoplastic, AUS, benign neoplasm, SUMP, SM, and malignant categories were 8.6%, 15.4%, 36.8%, 2.6%, 32.3%, 71.4%, and 100%, respectively.

CONCLUSION

The present results confirm the validity and diagnostic utility of MSRSGC, supporting its use in clinical practice to help devise adequate management strategies for salivary gland lesions.

Application of the Milan System for Reporting Submandibular Gland Cytopathology: An international, multi-institutional study

BACKGROUND

The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) is a 6-tier diagnostic category system with associated risks of malignancy (ROMs) and management recommendations. Submandibular gland fine-needle aspiration (FNA) is uncommon with a higher frequency of inflammatory lesions and a higher relative proportion of malignancy, and this may affect the ROM and subsequent management. This study evaluated the application of the MSRSGC and the ROM for each diagnostic category for 734 submandibular gland FNAs.

METHODS

Submandibular gland FNA cytology specimens from 15 international institutions (2013-2017) were retrospectively assigned to an MSRSGC diagnostic category as follows: nondiagnostic, nonneoplastic, atypia of undetermined significance (AUS), benign neoplasm, salivary gland neoplasm of uncertain malignant potential (SUMP), suspicious for malignancy (SM), or malignant. A correlation with the available histopathologic follow-up was performed, and the ROM was calculated for each MSRSGC diagnostic category.

RESULTS

The case cohort of 734 aspirates was reclassified according to the MSRSGC as follows: nondiagnostic, 21.4% (0%-50%); nonneoplastic, 24.2% (9.1%-53.6%); AUS, 6.7% (0%-14.3%); benign neoplasm, 18.3% (0%-52.5%); SUMP, 12% (0%-37.7%); SM, 3.5% (0%-12.5%); and malignant, 13.9% (2%-31.3%). The histopathologic follow-up was available for 333 cases (45.4%). The ROMs were as follows: nondiagnostic, 10.6%; nonneoplastic, 7.5%; AUS, 27.6%; benign neoplasm, 3.2%; SUMP, 41.9%; SM, 82.3%; and malignant, 93.6%.

CONCLUSIONS

This multi-institutional study shows that the ROM of each MSRSGC category for submandibular gland FNA is similar to that reported for parotid gland FNA, although the reported rates for the different MSRSGC categories were variable across institutions. Thus, the MSRSGC can be reliably applied to submandibular gland FNA.

Application of the Milan System for Reporting Salivary Gland Cytopathology: A Retrospective 12-Year Bi-institutional Study

OBJECTIVES

Multi-institutional studies are required for the validation of the Milan System for Reporting Salivary Gland Cytopathology (MSRSGC).

METHODS

A total of 1,560 fine-needle aspirations of the salivary glands were retrieved from two institutions for a 12-year period. The diagnoses were reclassified based on the MSRSGC. Risk of malignancy (ROM) for each category was calculated based on 694 histologic follow-up cases.

RESULTS

The ROM for each category was: 18.3% for nondiagnostic, 8.9% for nonneoplastic, 37.5% for atypia of undetermined significance (AUS), 2.9% for benign neoplasm, 40.7% for salivary gland neoplasm of uncertain malignant potential (SUMP), 100% for suspicious for malignancy, and 98.3% for malignant. The sensitivity, specificity, positive predictive rate, and negative predictive rates were 89%, 99%, 98%, and 96%, respectively.

CONCLUSIONS

The results of the current study are in keeping with the MSRSGC. The indeterminate categories of AUS and SUMP showed intermediate ROMs at 37.5% and 40.7%, respectively.

Implementation of the MILAN system for reporting salivary gland cytopathology: Interobserver concordance and cytohistological correlation of discordant cases

BACKGROUND

Fine needle aspiration cytology (FNAC) plays a pivotal role in evaluating salivary gland (SG) tumors. Several studies have shown diagnostic utility of MILAN system for reporting salivary gland cytopathology (MSRSGC) by examining risk of malignancy but only an occasional study has focused on interobserver variability. Hence, the present study was undertaken to assess the agreement among cytopathologists with varying experience in SG cytopathology using MSRSGC and to re-evaluate discordant cytohistological diagnoses for possible causes of misinterpretation.

METHODS

All SG lesions subjected to FNAC over a period of 3½ years were studied. The cases were critically reviewed by 2 pathologists with variable experience in cytopathology using MSRSGC and concordance level among them was calculated. Cytohistological discordant diagnoses were reclassified and possible causes of misinterpretation during routine reporting were evaluated.

RESULTS

Of 150 SG aspirates categorized according to MSRSGC, diagnostic disagreement between 2 pathologists was found in 10. Unweighted Cohen's Kappa score between consultant and resident was 0.812 (high). Among 55 cases with histological correlation, cytohistological discordance was seen in 12. True pitfalls constituted 50% of discordant cases while rest 50% were attributed to practical issues (turnaround time and heavy case load) during routine reporting.

CONCLUSION

MSRSGC can be used with good reproducibility between observers with variable cytopathology experience. Heterogeneous nature of SG neoplasm is a known pitfall in FNA diagnosis of SG neoplasms. During routine reporting turnaround time, heavy case load and reporting by cytopathologists with variable experience add on to challenges faced in reporting cytopathology of SG neoplasm.

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.

Cytological features of basal cell adenoma of salivary glands: Analysis of 19 cases emphasizing stromal spindle cells

BACKGROUND

Basal cell adenoma (BCA) of the salivary gland is a relatively rare benign tumor. Although the presence of stromal spindle cells is a characteristic histopathological feature, this finding has not been the focus of much attention in the cytodiagnosis of BCA. Thus, we analyzed the cytological features of BCA, especially the presence of stromal spindle cells.

METHODS

Patients who were histopathologically diagnosed with BCA and underwent preoperative fine-needle aspiration cytological examination were enrolled in this study. The cytological characteristics including arrangement and shape of the neoplastic cells, nuclear and cytoplasmic features, and the presence of stromal spindle cells were reviewed.

RESULTS

Nineteen patients were enrolled in the study. The cytological specimens were cellular and composed of small or large clusters or both. The neoplastic cells had scant cytoplasm and small round to oval nuclei. Basement membrane-like material was observed in 57.9%, and peripheral palisading was noted in 84.2%. Loose aggregates of stromal spindle cells were present in 63.2%, and the stromal spindle cells shown in the histological examination of 85.7% of cases were expressed in the cytological specimens.

CONCLUSION

This study clearly demonstrated the relatively high frequency of stromal spindle cells in cytological specimens of BCA. This finding is characteristic of BCA, and therefore, the combination of cytological features, including packed clusters of neoplastic cells with scant cytoplasm and small nuclei, peripheral palisading, and basement membrane-like material, and the presence of stromal spindle cells could increase the diagnostic success of BCA.

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.

The utility of the Milan System as a risk stratification tool for salivary gland fine needle aspiration cytology specimens

OBJECTIVE

To perform a retrospective investigation of our institutional experience with salivary gland fine needle aspirations (FNA) through the framework of The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) and assess the risks of neoplasm and malignancy for each diagnostic category.

METHODS

All salivary gland FNAs performed from January 2009 to December 2016 were retrospectively categorised according to the MSRSGC. When available, pre-operative cytological results were correlated with subsequent histological follow-up.

RESULTS

In total, 893 FNAs were reviewed. The specimens were retrospectively classified as nondiagnostic (ND: 13.5%), non-neoplastic (NN: 16.1%), atypia of undetermined significance (AUS: 10.8%), benign neoplasm (BN: 34.9%), salivary gland neoplasm of uncertain malignant potential (SUMP: 8.2%), suspicious for malignancy (SM: 2.7%) and malignant (M: 13.8%). Histological follow-up was available for 429 cases (48%); the majority (68.1%) were benign. The risks of neoplasm and malignancy for each category were as follows: ND: 64.5%, 16.1%; NN: 42.9%, 17.9%; AUS: 79.6%, 30.6%; BN: 100%, 2.2%; SUMP: 100%, 46.6%; SM: 94.7%, 78.9%; and M: 100%, 98.5%.

CONCLUSIONS

The MSRSGC is a useful classification scheme for stratifying salivary gland lesions according to their associated risk of malignancy and guiding clinicians toward appropriate management. Diagnostic pitfalls are seen in a small proportion of cases and a multidisciplinary approach for assessing salivary gland pathology is essential in their evaluation.