Retrospective assessment of the effectiveness of the Milan system for reporting salivary gland cytology: A systematic review and meta-analysis of published literature

Application of the Milan system for reporting salivary gland cytopathology to core needle biopsies of the parotid gland

AIMS

The Milan system for reporting salivary gland cytopathology was developed by an international group of experts and first published in 2018 with the goal to standardise reporting of salivary gland aspirates. Seven categories with distinct risks of malignancy were proposed. Core needle biopsies (CNB) of salivary glands are also common, but reporting lacks standardisation. Here we explore the feasibility of a Milan-like reporting system on CNB of the parotid gland.

METHODS AND RESULTS

Our laboratory information system was searched for parotid gland CNBs from 2010 to 2021. Reports were translated into a Milan-like reporting system. When available, CNB findings were correlated with cytology and resection specimens. In order to compare the performance of CNB with fine-needle aspirations (FNA), we established a second cohort of cases consisting of parotid FNA with surgical follow-up. The risk of neoplasia (RON) and risk of malignancy (ROM) was calculated for FNA and CNB Milan categories using cases with follow-up resection. We analysed 100 cases of parotid gland CNB. Of these cases, 32 underwent subsequent resection, while 52 had concurrent FNA. A total of 20 cases had concurrent FNA and underwent follow-up resection. In 63 (63%) cases, a specific diagnosis was provided on CNB, with 18 cases undergoing follow-up resection having an accuracy rate of 94%.

CONCLUSIONS

This study confirms the feasible of using a Milan-like system in the setting of parotid gland CNB with differentiation in RON and ROM. CNB allows assessment of architectural features that may allow more specific diagnoses in some cases.

The Milan system atypia of undetermined significance: 5-year performance data

BACKGROUND

The objective of this study was to evaluate the diagnostic performance of the category atypia of undetermined significance (AUS) at the authors' institution based on the Milan System for Reporting Salivary Gland Cytopathology.

METHODS

All AUS cases diagnosed at Fimlab Laboratories between January 1, 2018, and December 31, 2022, were included. Histologic verifications were checked until May 31, 2023. The upper-bound and lower-bound risk of malignancy and risk of neoplasm were calculated. The timelines between the pathology laboratory workflow and patient management were also calculated.

RESULTS

From 1157 fine-needle aspirations (FNAs), 162 (14.0%) AUS cases were diagnosed in 146 patients, with an average ± standard deviation age of 66.1 ± 14.9 years. There was variation in the AUS percentages, with higher values during the coronavirus disease 2019 pandemic years (15% and 17.5% in 2020 and 2021, respectively). Seventy-five cases (46.3%) had histologic follow-up: 16 were malignant neoplasms, and 36 were benign neoplasms. The upper and the lower bounds of the-risk of malignancy and risk of neoplasm were 21.3% and 69.3% and 9.9% and 32.1%, respectively. The average time from the first FNA with an AUS diagnosis to surgical resection ranged from 6 to 682 days, and the time to the first repeat FNA ranged from 10 to 691 days.

CONCLUSIONS

The results indicated higher percentages of AUS cases compared with the reference value, which may be attributed to the impact of the coronavirus disease 2019 pandemic. The risk of malignancy calculated in this study was closer to the reference value from the first edition of the Milan System for Reporting Salivary Gland Cytopathology compared with the second edition.

The International System for Reporting Serous Fluid Cytopathology: A Systematic Review and Meta-Analysis of Diagnostic Test Accuracy Studies

This is the first systematic review and meta-analysis of The International System (TIS) for reporting serous fluid cytopathology. Our aims were to present the pooled malignancy rate of each TIS reporting category and the diagnostic accuracy of cytology using this system. Database search using a predefined strategy was followed by study selection, data extraction, study quality assessment, and statistical analysis. Data derived from 16 eligible studies were pooled. The pooled rates of malignancy were as follows: 27% (95% CI; 16%-41%) for "nondiagnostic" (ND), 11% (95% CI; 7%-18%) for negative for malignancy" (NFM), 49% (95% CI; 37%-61%) for "atypia of undetermined significance" (AUS), 90% (95% CI; 81%-95%) for "suspicious for malignancy" (SFM), and 100% (95% CI; 98%-100%) for "positive for malignancy" (MAL). Studies performed exclusively in cancer hospitals showed higher pooled malignancy rates, compared with academic and community hospitals serving the general population, in the ND [40% (95% CI; 21%-62%) vs. 22% (95% CI; 11%-39%)], NFM [20% (95% CI; 13%-30%) vs. 9% (95% CI; 5%-17%)], and AUS categories [55% (95% CI; 47%-63%) vs. 46% (95% CI; 31%-62%)]. Notably, the difference was significant in the NFM category ( P =0.04). When both SFM and MAL cytology interpretations were considered as malignant outcomes, the pooled sensitivity and specificity were 68.74% (95% CI; 59.90%-76.39%) and 98.81% (95% CI; 98.18%-99.22%), respectively. In addition, the diagnostic odds ratio (DOR) was found to be 170.7 (95% CI; 96.2-303.3). Despite its strengths, our study also had some limitations. Therefore, future large-scale longitudinal studies could strengthen the findings of this review.

Challenging the concept of "risk of malignancy" in cytology

Several standardized systems for nongynecological cytopathology have been published following the successful implementation of The Bethesda System for Reporting Cervical Cytology. Each of these systems comprises a set of reporting categories accompanied by a risk of malignancy. However, in most cases, these risk of malignancy estimates have not been based on high-quality evidence and often may not be consider proper "risks" (because they have been estimated based on cross-sectional studies). This commentary discusses the problems related to the data used to generate these risks. To make nongynecological cytopathology reporting more evidence-based, large-scale prospective cohort studies and randomized trials, in addition to high-quality systematic reviews and meta-analyses, should be performed.

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.

The Milan System for Reporting Salivary Gland Cytopathology: the experience of a tertiary cancer center with emphasis on non-mucinous cysts and improving diagnostic results

INTRODUCTION

The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) was introduced in 2018 to standardize cytology reporting and guide patient treatment. We aimed to evaluate the utility of this system applied to patients at our cancer center.

MATERIALS AND METHODS

We retrospectively reviewed cases of salivary gland fine-needle aspirations (FNAs) performed in our institution (2019-2022). All were performed by radiologists and immediately assessed for specimen adequacy. The cytologic findings were classified into the MSRSGC except for non-mucinous cystic contents (NMCC) where the lesion was radiologically consistent with a cyst and totally collapsed after FNA. Such lesions were categorized as non-neoplastic (NN) instead of non-diagnostic (ND). The cytologic findings were compared to corresponding histologic findings (212 available cases), and the risk of malignancy was calculated.

RESULTS

Five hundred five FNAs were categorized as: 25 (4.95%) ND; 86 (17.03%) NN, of which 39 were NMCC; 9 (1.78%) atypia of undetermined significance; 138 (27.33%) benign neoplasms; 57 (11.29%) salivary gland neoplasm of undetermined malignant potential; 16 (3.17%) suspicious for malignancy; and 174 (34.46%) malignant. The risk of malignancy rates for the following categories were: ND, 40%; NN, 25%; atypia of undetermined significance, 0%; benign neoplasms, 1%; salivary gland neoplasm of undetermined malignant potential, 54.54%; suspicious for malignancy, 90.9%; and malignant, 100%. Thirty-one NMCC with available follow-up resolved/remained stable.

CONCLUSIONS

Our results validate the reproducibility of the MSRSGC applied in our cancer center. Based on the benign course of cysts with NMCC, we propose that such cases be categorized as NN, provided the cyst is totally resolved after FNA.

Milan system for reporting salivary gland cytology in diagnosis and surgery of parotid gland lesions

INTRODUCTION

A cytology report is always a challenge for both head and neck surgeons and cytopathologists to diagnose and manage parotid gland (PG) diseases, because of the various similar features between the lesions.

OBJECTIVES

The present study was conducted to assess our practice using the Milan System for Reporting Salivary Cytopathology (MSRSGC) and to evaluate the risk of malignancy (ROM) in different categories.

PATIENTS AND METHODS

The patients with parotid gland lesions were diagnosed by clinical examination, ultrasound, and FNAC under ultrasound guidance at our hospital from 1 May 2019 to 30 April 2021. The FNAC results were divided into six categories according to the Milan system. We calculated the ROM for each category of the Milan system based on histopathological follow-up.

RESULTS

This study included 204 patients. There were 115 men (56 %) aged 46-60 years. Pathology results were 33 cases for malignant and 182 cases for benign. The rate of malignancy for each category according to the MSRSGC were 23.1 % (non-neoplastic), 20 % (atypical), 50 % (neoplastic), 1 % (benign), 10.3 % (salivary neoplasm of uncertain neoplastic potential), 84.6 % (suspicious for malignancy), and 100 % (malignant) categories. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of FNAC with application of Milan system were respectively 90.9 %, 98.2 %, 90.9 %, 98.9 % and 97 %.

CONCLUSION

When the Milan system was applied, FNAC had a high efficacy, suggesting that MSRSGC can improve the communication between the cytopathologist and the surgeon. This system can allow the surgeon to decide the extent of the surgery.

Evaluation of Fine Needle Aspiration Cytopathology in Salivary Gland Tumors under Milan System: Challenges, Misdiagnosis Rates, and Clinical Recommendations

(1) Background: Salivary gland tumors are rare in the head and neck. To determine the need and extent of surgical intervention, fine needle aspiration (FNA) is a widely accepted tool to approach salivary gland lesions. However, the FNA cytology varies between entities, while the lack of uniform terminology makes diagnosis more challenging. Since establishing the Milan system for reporting salivary gland cytopathology (MSRSGC) has become an increasingly accepted reporting standard, further examination and detailed recommendations were needed. (2) Methods: Between April 2013 and October 2021, 375 cases with FNA and salivary gland resection were retrospectively collected. All FNA specimens were reclassified according to the criteria of MSRSGC. After surgical excision, the FNA data were compared with the histological diagnosis to estimate the risk of malignancy (ROM), the risk of neoplasm (RON), and the diagnostic accuracy for each diagnostic category. (3) Results: Our cohort's distribution of ROM and RON was similar to the MSRSGC's recommendation. Carcinoma ex pleomorphic adenoma (CXPA) has the highest rate (66.7%) of misdiagnosed as a nonneoplastic lesion or benign salivary gland tumor. Pleomorphic adenoma (PA) and Warthin's tumor were the most common benign salivary gland tumors, while the cytology diagnosis of Warthin's tumor seems more challenging than PAs. (4) Conclusions: Despite the convenience and effectiveness of MSRSGC, we suggest close follow-up, re-biopsy, or surgical removal for salivary lesions even in Milan IVA-Benign for possibly missing FNA of malignancy, mixed lesions, or prevention of malignant transformation.

Assessing the Agreement Between Preoperative Fine-Needle Aspiration Cytology (FNAC) Done for Major Salivary Gland Neoplasm When Reported by Head and Neck Pathologists and Non-head and Neck Pathologists with Its Final Histopathology

The preoperative FNA is an important investigation in the workup of a salivary gland pathology. A preoperative diagnosis is important to plan management and counsel patients accordingly. In this study, we aimed to assess the agreement between the preoperative FNA and the final histopathology report when reported by a head and neck and a non-head and neck pathologist. All patients with major salivary gland neoplasm having undergone a preoperative FNA before surgery from January 2012 to December 2019 at our hospital were included in the study. Analysis was done to check for concordance between head and neck and non-head and neck pathologists of the preoperative FNA and final histopathology. Three hundred and twenty-five patients were included in the study. The preoperative FNA could identify the tumour as benign or malignant in the majority (n = 228, 70.1%). The agreement between the preoperative FNA, frozen section diagnosis and the reporting of grade in the frozen section and the final HPR was slightly better with the head and neck pathologist (kappa = 0.429, kappa = 0.698 and kappa = 0.257), respectively, than with the non-head and neck pathologist (kappa = 0.387, kappa = 0.519 and kappa = 0.158), all of which was statistically significant (p < 0.001). The diagnosis made with the preoperative FNA and reporting in the frozen section had a fair agreement with the final histopathology when reported by a head and neck pathologist in comparison to a non-head and neck pathologist.

Salivary gland cancer: ESMO-European Reference Network on Rare Adult Solid Cancers (EURACAN) Clinical Practice Guideline for diagnosis, treatment and follow-up

•This ESMO–EURACAN Clinical Practice Guideline provides key recommendations for managing salivary gland cancer. •The guideline covers clinical and pathological diagnosis, staging and risk assessment, treatment and follow-up. •Treatment algorithms for parotid, submandibular, sublingual and minor salivary gland cancer are provided. •The author group encompasses a multidisciplinary group of experts from different institutions and countries in Europe. •Recommendations are based on available scientific data and the authors’ collective expert opinion.

Application of the Milan System for Reporting Salivary Gland Cytopathology: A systematic review and meta-analysis

BACKGROUND

The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) is a standard, evidence-based classification system for salivary gland fine-needle aspiration (SG-FNA). Since it was published in 2018, many researchers across the world have applied this uniform reporting system to their cohorts.

METHODS

The authors comprehensively reviewed cohort studies conducted since publication of the MSRSGC and performed a meta-analysis. The risk of neoplasm and the risk of malignancy (ROM) were calculated for each diagnostic category, and their diagnostic efficacy was evaluated.

RESULTS

Thirty-five studies were included in the meta-analysis. The total number of SG-FNAs was 10,706, and 7168 of those had histopathologic follow-up. The ROM for each category was: nondiagnostic, 11.4%; nonneoplastic, 10.9%; atypia of undetermined significance, 30.5%; neoplasm-benign, 2.8%; neoplasm-salivary gland neoplasm of uncertain malignant potential, 37.7%; suspicious for malignancy, 83.8%; and malignant, 97.7%. Low-level heterogeneity was observed in ROM estimation. The sensitivity, specificity, and diagnostic odds ratio for differentiating malignant and benign lesions were 88.0%, 98.5% and 520.3, respectively.

CONCLUSIONS

The reporting of SG-FNA using the MSRSGC demonstrated high diagnostic accuracy. The ROM for each category was generally concordant with the recommendations, except for the suspicious for malignancy category, which was significantly higher than the reference value. The tiered, standardized classification system would benefit the clinical management of salivary gland lesions.

Nondiagnostic category of Milan System for Reporting Pediatric Salivary Gland Cytopathology: outcomes and root cause analysis

BACKGROUND

Fine-needle aspiration (FNA) results classified as the nondiagnostic category of the Milan system for reporting salivary gland cytopathology (MSRSGC) may be infrequently encountered in children. Clinical management may be challenging due to lack of data regarding outcomes and underlying causes.

METHODS

We retrospectively analyzed 106 consecutive pediatric salivary gland FNAs (2000-2020; 45% performed under image guidance). The outcomes of patients with nondiagnostic results were analyzed. Clinical parameters, FNA procedural parameters, and histopathologic parameters were compared between diagnostic and nondiagnostic cases. A root cause analysis was performed using the fishbone diagram and the 5 Whys method.

RESULTS

A total of 103 initial FNAs were identified. The nondiagnostic rates for initial and repeat biopsy were 16% (16/103) and 67% (2/3), respectively. Initial nondiagnostic FNAs were most frequently managed by clinical/radiologic follow-up only (56%, 9/16), followed by direct surgery (19%, 3/16) and repeat FNA (19%, 3/16). By histologic and clinical/radiologic follow-up, the risk of malignancy for nondiagnostic cases was zero. Palpation guidance (P < .05), inadequate sampling determined by rapid on-site evaluation (P < .01), and lesions with cystic, vascular, or diffuse nature (P < .05) were significantly associated with nondiagnostic results. By root cause analysis, proceduralist sampling error and lack of ultrasound guidance were the most common primary and secondary causes, respectively.

CONCLUSIONS

Pediatric salivary gland lesions of the nondiagnostic MSRSGC category have minimal risk of malignancy and may be successfully managed by clinical/radiologic follow-up. The root causes for nondiagnostic results were often multifactorial and primarily related to proceduralist sampling, characteristics of the lesions, and lack of ultrasound guidance.

Multi-institutional validation of a modified scheme for subcategorizing salivary gland neoplasm of uncertain malignant potential (SUMP)

BACKGROUND

The salivary gland neoplasm of uncertain malignant potential (SUMP) category in the Milan System is diagnostically challenging. This study aims to validate a modified scheme for subcategorizing SUMP in a large multi-institutional cohort.

METHODS

Retrospective review of salivary gland fine-needle aspirations (FNAs) from 10 institutions were classified based on the Milan System. Cases diagnosed as SUMP with available cytology slides and surgical follow-up were retrieved for review and subcategorized based on a modified scheme as follows: basaloid SUMP (B1: absent/scant nonfibrillary matrix; B2: presence of nonfibrillary/mixed-type matrix), oncocytic/oncocytoid SUMP (O1: with mucinous background; O2: without mucinous background), and SUMP not otherwise specified (NOS).

RESULTS

A total of 742 (7.5%) cases from 9938 consecutive salivary gland FNAs were classified as SUMP. Among them, 525 (70.8%) had surgical follow-up and 329 (62.7%) were available for review. The overall risk of malignancy (ROM) of SUMP was 40.4%. There were 156 cases (47.4%) subcategorized as basaloid SUMP with a ROM of 36.5%, 101 (30.7%) as oncocytic/oncocytoid SUMP with a ROM of 52.5%, and 72 (21.9%) as SUMP NOS with a ROM of 31.9%. The ROM of oncocytic/oncocytoid SUMP was significantly higher than basaloid SUMP (P = .0142) and SUMP NOS (P = .0084). No significant differences in ROM were noted between B1 and B2 (36.7% vs 36.4%, P = 1.0000) and O1 and O2 (65.2% vs 48.7%, P = .2349).

CONCLUSIONS

The ROM of oncocytic/oncocytoid SUMP was 52.5% and significantly higher than that of basaloid SUMP (36.5%, P = .0142) and SUMP NOS (31.9%, P = .0084), whereas no significant differences in ROM were noted for cases with different types of extracellular matrix or background material.

The Paris System for Reporting Urinary Cytology: A Meta-Analysis

The Paris System (TPS) for Reporting Urinary Cytology is a standardized, evidence-based reporting system, comprising seven diagnostic categories: nondiagnostic, negative for high-grade urothelial carcinoma (NHGUC), atypical urothelial cells (AUC), suspicious for high-grade urothelial carcinoma (SHGUC), HGUC, low-grade urothelial neoplasm (LGUN), and other malignancies. This study aimed to calculate the pooled risk of high-grade malignancy (ROHM) of each category and demonstrate the diagnostic accuracy of urine cytology reported with TPS. Four databases (PubMed, Embase, Scopus, Web of Science) were searched. Specific inclusion and exclusion criteria were applied, while data were extracted and analyzed both qualitatively and quantitatively. The pooled ROHM was 17.70% for the nondiagnostic category (95% CI, 0.0650; 0.3997), 13.04% for the NHGUC (95% CI, 0.0932; 0.1796), 38.65% for the AUC (95% CI, 0.3042; 0.4759), 12.45% for the LGUN (95% CI, 0.0431; 0.3101), 76.89 for the SHGUC (95% CI, 0.7063; 0.8216), and 91.79% for the HGUC and other malignancies (95% CI, 0.8722; 0.9482). A summary ROC curve was created and the Area Under the Curve (AUC) was 0.849, while the pooled sensitivity was 0.669 (95% CI, 0.589; 0.741) and false-positive rate was 0.101 (95% CI, 0.063; 0.158). In addition, the pooled DOR of the included studies was 21.258 (95% CI, 14.336; 31.522). TPS assigns each sample into a diagnostic category linked with a specific ROHM, guiding clinical management.

Utility of the Milan system for reporting salivary gland cytopathology during rapid on-site evaluation (ROSE) of salivary gland aspirates

OBJECTIVE

Rapid on-site evaluation (ROSE) is a fine needle aspiration (FNA) technique for ensuring sampling adequacy and triaging samples. The Milan system for reporting salivary gland cytopathology (MSRSGC) is a standardised reporting system which aims to improve risk stratification. There is scant literature on the diagnostic value and agreement of MSRSGC on ROSE with final cytological diagnosis in salivary gland FNAs. We aimed to assess the concordance of MSRSCG categorisation and diagnosis on ROSE with final cytological and histological diagnosis.

METHODS

This prospective study included consecutive salivary gland FNAs for which ROSE was performed over a six-month period. MSRSGC category and diagnosis on ROSE were compared with the final cytological diagnosis and MSRSGC category, and histopathological diagnosis, where available.

RESULTS

Sixty salivary gland aspirates were included. The adequacy rate with ROSE was 100%. Using the MSRSGC classification during ROSE, 26 (43.2%) samples were categorised as benign neoplasm, 21 (35%) as malignant neoplasm, 9 (15%) as non-neoplastic, and one each (1.7%) belonged to the remaining four categories. MSRSGC categorisation on ROSE concurred with final the cytological diagnosis in 58/60 cases (96.7%). Discrepancies in MSRSGC categories on ROSE included one atypia of undetermined significance with final report as non-neoplastic, and one non-diagnostic as suspicious for malignancy. Good correlation of MSRSGC categories on ROSE with final histopathological diagnosis (88.9% concordance) was also noted.

CONCLUSIONS

MSRSGC on ROSE shows good concordance with final cytology and histopathology diagnosis, indicating that categorisation according to MSRSGC has utility in ensuring that adequate material is obtained and triaged appropriately for the diagnosis of salivary gland aspirates.

Application of the Milan System for Reporting Pediatric Salivary Gland Cytopathology: Analysis of histologic follow-up, risk of malignancy, and diagnostic accuracy

BACKGROUND

The diagnosis and management of salivary gland tumors in pediatric patients can be challenging. The utility of fine-needle aspiration (FNA) cytopathology and the performance of the Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) in this age group have not been systematically assessed. The paucity of data has contributed to the controversial role of FNA cytopathology in the presurgical management of these patients.

METHODS

The authors retrospectively analyzed 104 pediatric salivary gland FNAs (2000-2020). A correlation with the available histopathologic follow-up (n = 54) was performed. The distribution percentages, the risk of neoplasm (RON), and the risk of malignancy (ROM) were assessed for each category of the MSRSGC.

RESULTS

The overall sensitivity, specificity, negative predictive value, and positive predictive value of pediatric salivary gland FNAs were 80%, 97%, and 92%, respectively. The RON values for the nondiagnostic, nonneoplastic, atypia of undetermined significance, benign neoplasm, salivary gland neoplasm of uncertain malignant potential, suspicious for malignancy, and malignant categories were 60%, 11%, 100%, 100%, 100%, 100%, and 100%, respectively, whereas the ROM values were 0%, 11%, 100%, 6%, 67%, 100%, and 100%, respectively. The percentage of nonneoplastic FNAs was greater in comparison with the adult population (52% vs 8%). All neoplasms in patients aged 0 to 10 years were malignant, whereas benign neoplasms occurred only in patients aged ≥11 years; this supported an inverse correlation between age and malignancy rate in salivary gland neoplasms.

CONCLUSIONS

FNA cytopathology demonstrates excellent diagnostic performance in differentiating malignant and benign pediatric salivary gland lesions. The MSRSGC is a valuable tool for standardization of the reporting and preoperative risk stratification of these lesions.

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.

Accuracy, predictability and prognostic implications of fine-needle aspiration biopsy for parotid gland tumours: A retrospective case series

OBJECTIVE

To evaluate the precision and utility of fine-needle aspiration (FNA) in differentiating between benign and malignant parotid tumours, and the implications of FNA results on management and outcomes.

DESIGN

Retrospective case series.

SETTING

Tertiary medical centre.

PARTICIPANTS

All adults who underwent preoperative FNA, followed by postoperative histological examination, between 1986 and 2014.

MAIN OUTCOME MEASURES

Differences in clinical management and outcomes of patients with parotid masses in light of FNA results.

RESULTS

We analysed 505 samples from 485 patients. According to histopathological results, preoperative FNA successfully identified benign tumours in 89% of the cases (362/405) and only 59% of malignant tumours (59/100). Overall sensitivity and specificity of FNA in distinguishing between different subtypes of benign lesions were 80% and 99%, respectively, whereas positive predictive value (PPV) and negative predictive value (NPV) were 85% and 98%. Moreover, malignant lesions subtyping had high false-positive and false-negative rates with sensitivity, specificity, PPV and NPV of 44%, 100%, 75% and 99%, respectively. Additionally, when FNA falsely classified malignant tumours as benign, surgeries were inappropriately delayed and the durations of surgeries and hospitalisations were shorter, compared to true malignant FNA results. Interestingly, survival was not affected in falsely benign lesions that were mostly low-grade, conversely non-diagnostic FNA for malignant tumours resulted in decreased survival.

CONCLUSIONS

Our findings highlight the limitations of FNA as a decision-making tool in preoperative evaluation of parotid masses. Clinicians should take into account that FNA is inaccurate for identifying specific subtypes of malignant lesions, which may eventually delay treatment and influence outcome.

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.

The Milan System, from Its Introduction to Its Current Adoption in the Diagnosis of Salivary Gland Cytology

Salivary gland masses are often encountered in the everyday practice of cytopathology. It is commonly known that the cytologic interpretation of these lesions can pose diagnostic problems due to overlapping cytomorphologic features. Fine needle aspiration (FNA) of salivary lesions shows good to excellent sensitivity and specificity in differentiating a neoplastic from a non-neoplastic process and in diagnosing common tumors such as pleomorphic adenoma. However, its value is limited in diagnosing specific neoplastic entities especially those with well-differentiated morphology. In light of this gap, an international group of pathologists has proposed a management-oriented, tiered classification for reporting salivary gland FNA specimens, “The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC)”. Similar to other classification systems, the MSRSGC scheme comprises six diagnostic categories, which were linked with a specific risk of malignancy (ROM) and management. In this review article, the author evaluated the published literature on FNA in diagnosing salivary gland lesions with the adoption of the Milan system since its introduction in the daily practice of salivary cytopathology.

Management of Salivary Gland Malignancy: ASCO Guideline

PURPOSE

To provide evidence-based recommendations for practicing physicians and other healthcare providers on the management of salivary gland malignancy.

METHODS

ASCO convened an Expert Panel of medical oncology, surgical oncology, radiation oncology, neuroradiology, pathology, and patient advocacy experts to conduct a literature search, which included systematic reviews, meta-analyses, randomized controlled trials, and prospective and retrospective comparative observational studies published from 2000 through 2020. Outcomes of interest included survival, diagnostic accuracy, disease recurrence, and quality of life. Expert Panel members used available evidence and informal consensus to develop evidence-based guideline recommendations.

RESULTS

The literature search identified 293 relevant studies to inform the evidence base for this guideline. Six main clinical questions were addressed, which included subquestions on preoperative evaluations, surgical diagnostic and therapeutic procedures, appropriate radiotherapy techniques, the role of systemic therapy, and follow-up evaluations.

RECOMMENDATIONS

When possible, evidence-based recommendations were developed to address the diagnosis and appropriate preoperative evaluations for patients with a salivary gland malignancy, therapeutic procedures, and appropriate treatment options in various salivary gland histologies.Additional information is available at www.asco.org/head-neck-cancer-guidelines.

Diagnostic performance of Milan system for reporting salivary gland cytopathology: A prospective study

BACKGROUND

Fine-needle aspiration (FNA) is a well-established modality for diagnosing salivary gland pathologies. The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) provides a standardized uniform framework leading to an evidence-based risk of malignancy (ROM). Based on the current literature, ROM in the 6-tier MSRSGC ranges from <5% for neoplasm-benign to >90% for the malignant category. Here, we report our institutional experience adopting MSRSGC.

METHODS

The cytopathology group at our institution implemented MSRSGC at the end of 2018. Through a query of our laboratory information system, we identified all salivary gland FNA cases from 27 November 2018 to 26 October 2020. The pertinent surgical pathology follow-up was also extracted. After manual curation, data was analyzed in Rv4.0.2.

RESULTS

Our cohort comprised of 315 patients undergoing 343 salivary gland FNA biopsies, predominantly on the parotid (90%), 162 with a surgical pathology follow-up. The risk of malignancy ranged from 3.2% in neoplasm-benign (IVA) to 100% in suspicious for malignancy (V) and malignant (VI) categories. ROM in the other categories was: 12.5% for non-diagnostic, 0 for non-neoplastic, 33.3% for atypia of undetermined significance, and 41.9% for salivary gland neoplasm of uncertain malignant potential (SUMP). Most SUMP cases had a basaloid or oncocytoid cytomorphology with similar ROM. In distinguishing benign and malignant salivary gland lesions, FNA had adequacy of 93.6%, a diagnostic yield of 62.2%, a sensitivity of 93.1% and a specificity of 100%.

CONCLUSIONS

MSRSGC was successfully adopted by our cytology group and clinicians, with overall diagnostic performance similar to previous studies.

Analysis of the risk of malignancy associated with the basaloid and oncocytic subtypes of the salivary gland neoplasm of unknown malignant potential (SUMP) category in the Milan system

BACKGROUND

The salivary gland neoplasm of unknown malignant potential (SUMP) category reflects the cytomorphologic overlap and complexity of reporting salivary gland cytology in the Milan system. It includes neoplasms for which a diagnosis of a specific entity cannot be made and, more importantly, for which a carcinoma cannot be entirely excluded. For risk stratification, the subcategorization of SUMP based on the predominant cell type is recommended. This study was aimed at evaluating the risk of neoplasm (RON) and the risk of malignancy (ROM) of the basaloid and oncocytic subtypes of the SUMP category.

METHODS

A retrospective analysis of 482 salivary gland fine-needle aspirations from 2012 to 2019 resulted in 48 SUMP cases. The cytology of these cases was reviewed and reclassified as the basaloid or oncocytic subtype. Surgical follow-up was available for 36 cases. The RON and ROM for each subtype were calculated.

RESULTS

The RON and ROM were 100% and 23%, respectively, for monomorphic basaloid tumors and 88% and 58.8%, respectively, for monomorphic oncocytic tumors. The ROM for basaloid tumors was 8.3% without matrix/with minimal matrix and 60% with an nonfibrillary matrix. The ROM for oncocytic tumors was 50% without a cystic background and 60% with a cystic or mucinous background. The difference was not statistically significant for either of the subgroups.

CONCLUSIONS

Even though statistically not significant in our study, the differential ROMs within the oncocytic and basaloid subgroups help in the risk stratification of SUMP cases. Further subcategorization based on the stroma and background helps in limiting the differential diagnosis but does not necessarily add to the value of the risk stratification.

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.

Accuracy of fine-needle aspiration cytology in the diagnosis of salivary gland masses according to the Milan reporting system and to an in-house system

BACKGROUND

This study aims to assess in our institutional experience the accuracy of fine needle aspiration cytology (FNAC) in the diagnosis of salivary gland masses (SGM) according to the Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) and to an in-house system.

METHODS

The study included 189 FNACs conducted between January 2011 and December 2019. The FNACs, classified according to the in-house system, were reclassified according the MSRSGC. Taking histopathology as gold standard, the measures of diagnostic accuracy of FNAC were determined for suspicion for malignancy (SFM) and malignant categories.

RESULTS

According to the in house system, FNAC diagnoses were classified as: 23 (12.2%) non-diagnostic (ND), 23 (12.2%) non-neoplastic (NN), 119 (62.9%) benign neoplasm (BN), 10 (5.2%) indefinite neoplasm (IN), 2 (1.1%) SFM, and 12 (6.4%) malignant (M). Based on the MSRSGC, there were 3 (1.5%) cases of atypia of undetermined significance (AUS) and 7 (3.7%) neoplasms of uncertain malignant potential (SUMP). The number of ND, NN, BN, SFM, and M cases were identical in the two systems. For both systems, the sensitivity, the specificity, the positive predictive value, the negative predictive value, and the accuracy for malignancy diagnosis were 77.8%, 100%, 100%, 97.6%, and 97.8%, respectively.

CONCLUSION

According to the MSRGC and to our in-house reporting system, FNAC is an accurate technique for the diagnosis of malignant salivary tumors with excellent specificity and good sensitivity. However, MSRGC has the advantage of standardization of salivary gland cytology reporting.

Guidelines of the French Society of Otorhinolaryngology-Head and Neck Surgery (SFORL), part I: Primary treatment of pleomorphic adenoma

INTRODUCTION

The authors present the guidelines of the French Society of Otorhinolaryngology-Head and Neck Surgery (SFORL) for the diagnosis and treatment of pleomorphic adenoma (PA) of the salivary glands.

METHOD

A review of the literature was performed by a multidisciplinary task force. Guidelines were drafted based on the articles retrieved and the workgroup members' individual experience. Guidelines were graded A, B, C or expert opinion by decreasing level of evidence.

RESULTS

In clinically suspected salivary gland PA, MRI should be performed, including head and neck lymph node levels. Fine needle aspiration cytology is particularly recommended for tumours difficult to characterise by MRI. Frozen section biopsy should be performed to confirm diagnosis and adapt the surgical procedure in case of intraoperative findings of malignancy. Complete resection of the parotid PA should be performed en bloc, including margins, when feasible according to tumour location, while respecting the facial nerve. Enucleation (resection only in contact with the tumour) is not recommended. For the accessory salivary and submandibular glands, complete en bloc resection should be performed.

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.

Retrospective implementation of the Milan system for reporting salivary gland cytopathology; a review of 5 years in a specialized cancer center

BACKGROUND

The Milan system for reporting salivary gland cytopathology (MSRSGC) aims to standardize terminology, facilitate communication, and optimize management by providing risk of malignancy (ROM) for each category. Our retrospective cohort aims to study the reproducibility of reporting using the MSRSGC and to calculate the ROM for each category.

METHODS

Cases of fine needle aspiration (FNA) of salivary glands and related cervical lymph nodes were retrieved from our files between 2015 to 2019. From a total of 63 cytology cases, 57 cases had available material for cytological reexamination of which 45 cases had follow up data. All cases were reviewed independently by two pathologists and reclassified based on the MSRSGC. The reclassification of cases for both pathologists was compared and the ROM for each diagnostic category was calculated.

RESULTS

The 57 cases were studied. Both pathologists had initial concordance in classification of 52 of 57 cases. The remainder five cases were concurred upon after combined review. The cases were classified as: Non Diagnostic (ND); (n = 8), Non Neoplastic (NN); (n = 7), Atypia of Undetermined Significance (AUS); (n = 8), Neoplasm Benign (NB) (n = 10), Salivary Gland Neoplasm of Uncertain Malignant Potential (SUMP) (n = 5), Suspicious for Malignancy (SM) (n = 1) and Malignant (M) (n = 18). The ROM was: ND: (33.3%); NN: (0%); AUS (33.3%); NB (0%); SUMP (25%); SM (100%) and M (100%).

CONCLUSION

Applying the MSRSGC is reproducible which facilitates standardization of reports and stratifying cases preoperatively. In general, the ROM for our cases was close to that reported in the literature.

Risk stratification and clinical outcome in the atypia of undetermined significance category in the Milan System for Reporting Salivary Gland Cytopathology

BACKGROUND

Atypia of undetermined significance (AUS) is a category of the Milan System for Reporting Salivary Gland Cytopathology that refers to salivary gland fine-needle aspiration (FNA) specimens that cannot be definitively diagnosed as neoplastic or nonneoplastic.

METHODS

The AUS FNA samples were selected from a large academic institution from 2008 through 2018. The AUS cases were divided into 6 subgroups. The risk of malignancy (ROM), risk of neoplasm (RON), and clinical outcomes for each subgroup were evaluated.

RESULTS

A total of 123 cases were found (76 males and 47 females with a mean age of 62 years [range, 6-94 years]). The parotid gland was the most common FNA site (103 cases), followed by the submandibular gland (9 cases). The overall RON and ROM were 63% and 47%, respectively. Among the subgroups, salivary gland lymph nodes or lymphoid lesions was the most common diagnosis (42%), whereas mucinous cystic lesions with no or a scant epithelial component was the least common (2%). The specimens with preparation artifacts category had the highest RON and ROM (100% for both), whereas the reactive and reparative atypia indefinite for a neoplasm category had the lowest RON and ROM (7% for both). The salivary gland lymph nodes or lymphoid lesions indefinite for a lymphoproliferative disorder category had the second highest RON and ROM at 77% and 74%, respectively.

CONCLUSIONS

The overall RON and ROM for the AUS category were 63% and 47%, respectively. The RON and ROM varied among the different AUS subgroups, being highest in the specimens with preparation artifacts category and lowest in the reactive and reparative atypia category, thereby demonstrating the importance of subgrouping in the AUS specimens.

Assessing the diagnostic accuracy for pleomorphic adenoma and Warthin tumor by employing the Milan System for Reporting Salivary Gland Cytopathology: An international, multi-institutional study

BACKGROUND

The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) has established distinct diagnostic categories for reporting cytopathological findings, and each is associated with a defined risk of malignancy (ROM). However, the ROM is applied at the overall category level and is not specific for particular morphological entities within a category. Here, the diagnostic performance of the MSRSGC for pleomorphic adenoma (PA) and Warthin tumor (WT) is reported.

METHODS

The pathology archives of 11 institutions from 4 countries were retrospectively searched to identify all salivary gland fine-needle aspiration (FNA) biopsies with a differential or definitive diagnosis of PA or WT and all resection specimens with a diagnosis of PA or WT; only paired cases were included. All FNA diagnoses were retrospectively classified according to the MSRSGC.

RESULTS

A total of 1250 cases met the inclusion criteria, and they included 898 PA cases and 352 WT cases. The ROM in the benign neoplasm category was 3.0% and 1.3% for cases with a differential or definitive diagnosis of PA and WT, respectively. The ROM in the salivary gland neoplasm with uncertain malignant potential (SUMP) category was 2.7% and 18.8% for PA and WT, respectively (P = .0277). The diagnostic accuracy for PA and WT was 95.1% and 96.1%, respectively.

CONCLUSIONS

The diagnostic accuracy for PA and WT on FNA is high. Furthermore, these findings highlight the difference in the ROMs associated with 2 specific differential diagnoses in the SUMP category: basaloid neoplasms and oncocytoid neoplasms.

Should uncertainty concerning the risk of malignancy be included in diagnostic (nongynecologic) cytopathology reports?

In diagnostic cytology, the known site-specific false positive rates at various anatomical sites for the risk malignancy (ROM) when a confirmed malignant diagnosis is made are comparatively well documented. ROM figures for diagnostic cytology specimens may vary according to the anatomical site of the specimen, the exact nature of the specimen received, the staining method(s) used, and the use of additional laboratory techniques including molecular profiling; furthermore, they often differ to some extent from institution to institution, between differing cytologists within the same institution, and over time. A brief literature review for a selected group of routine diagnostic cytology specimens shows a published ROM for a confirmed malignant diagnosis as follows: bile duct brushings, ~99% (range, 97%-100%); breast fine needle aspiration, 98.5% (range, 92%-100%); serous effusion fluid, 98.9% (range, 90%-100% although lower for squamous cell carcinoma, mesothelioma, and lymphoma), pulmonary endobronchial ultrasound cytology, ~99% (range, 86.6%-100%); thyroid FNA, 98% (range, 97%-99% if NIFTP tumors are excluded), salivary gland FNA, ~90%; (range 57%-100%) and lateral neck cyst FNA, ~99% (range, 95.5%-100%). Because most diagnostic cytology specimens have a small but accepted false-positive rate, this information is vitally important for the clinical management of patients and for shared patient decision making. In our view, the known false-positive rate for a given diagnostic cytology specimen could be included within the cytology report to assist in explaining the limitations of the diagnostic cytology interpretation and help facilitate the clinical decision-making process.

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.

Current classification systems and standardized terminology in cytopathology

The history of classification systems and the search for a unified nomenclature in cytopathology spans several decades and expresses the preoccupation of all those involved to make cytopathology a reliable diagnostic tool and a trusted screening method. Early classification schemes, applicable to exfoliative and aspiration cytology, attempted to set some basic standards for how non-gynecological cytopathology findings should be reported. While useful in establishing some basic guidelines, these were not specific to the various fields of non-gynecologic cytopathology, often burdened with specific problems. Cytopathology has evolved tremendously in the last couple of decades, undoubtedly boosted by the emergence of various classification schemes that, more than ever, are based on evidence gathered by professionals across the globe. The benefit of classification systems and standardized nomenclature in cytopathology is to provide useful, clear, and clinically relevant information for clinicians and ultimately to provide the best patient care. Standardized reporting systems make cytopathology reports more meaningful and robust. It now became standard that these include by default elements, such as adequacy criteria, diagnostic groups, risk of malignancy (ROM), and recommendations for patient management. In this brief review, we attempted to summarize how these classification schemes emerged and how they are reshaping the landscape of diagnostic cytopathology.

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.

Cytologic grading of primary malignant salivary gland tumors: A blinded review by an international panel

BACKGROUND

Fine needle aspiration (FNA) is commonly used for the preoperative evaluation of salivary gland tumors. Tumor grade is a key factor influencing clinical management of salivary gland carcinomas (SGCs). To assess the ability to grade nonbasaloid SGCs in FNA specimens, an international panel of cytopathologists convened to review and score SGC cases.

METHODS

The study cohort included 61 cases of primary SGC from the pathology archives of 3 tertiary medical centers. Cases from 2005 to 2016 were selected, scanned, and digitized. Nineteen cytopathologists blinded to the histologic diagnosis reviewed the digitized cytology slides and graded them as low, high, or indeterminate. The panelists' results were then compared to the tumor grades based on histopathologic examination of the corresponding resection specimens.

RESULTS

All but 2 of the 19 (89.5%) expert panelists review more than 20 salivary gland FNAs per year; 16 (84.2%) of the panelists work at academic medical centers, and 13 (68.4%) have more than 10 years' experience. Participants had an overall accuracy of 89.4% in the grading of SGC cases, with 90.2% and 88.3% for low- and high-grade SGC, respectively. Acinic cell carcinoma and mucoepidermoid carcinoma had the highest degree of accuracy, while epithelial-myoepithelial carcinoma and salivary duct carcinoma had the lowest degree of accuracy. As expected, the intermediate-grade SGC cases showed the greatest variability (high-grade, 42.1%; low-grade, 37.5%, indeterminate, 20.4%).

CONCLUSION

This study confirms the high accuracy of cytomorphologic grading of primary SGC by FNA as low- or high-grade. However, caution should be exercised when a grade cannot be confidently assigned.

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.

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.

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.

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.