Impact of the Milan System for Reporting Salivary Gland Cytology on risk assessment when used in routine practice in a real-time setting

How important are the cytomorphologic subtypes of the salivary gland neoplasm of uncertain malignant potential (SUMP) category in the Milan system for reporting salivary gland cytology? An institutional experience 2018-2024

INTRODUCTION

Salivary gland neoplasm of uncertain malignant potential (SUMP) is an important diagnostic category of the Milan System for reporting salivary gland cytology (MSRSGC). Further subcategorization by cytomorphologic subtypes has been recommended to risk-stratify cases. In this study, our institutional experience with the risk of neoplasm (RON) and risk of malignancy (ROM) based on cytomorphologic subcategorization of SUMP is reported. We also report the prevalence of malignancy (POM) at our institution.

METHODS

The pathology database was queried for cases of fine-needle aspiration (FNA) diagnosed as SUMP along with follow-up at our institution from 2018-February 2024. This study was approved by an institutional review board.

RESULTS

Of 1159 cases of salivary gland FNA specimens reported as per MSRSGC at our institution, 14.8% (171/1159 cases) were diagnosed as SUMP, with these reports verified by at least 16 cytopathologists. Surgical follow-up was available for 139/171 (81.3%) of these cases, for which the original cytomorphologic subgroups were as follows: 65 (46.8%) basaloid, 48 (34.5%) oncocytic/oncocytoid, 14 (10.1%) myoepithelial, 9 (6.5%) other, 2 (1.4%) clear cell, and 1 (0.7%) mucinous. The POM within SUMP at our institution is within a range of 29.8%-36.7%. When considering all cases, our institutional RON for SUMP was 97.8% (136/139), and the ROM was 36.7% (51/139). Notably, a significant portion of cases (36%, 50/139) underwent review at a daily intradepartmental consensus conference. Analysis revealed that SUMP cases that underwent consensus review had a ROM of 46% (23/50), versus 31.5% (28/89) in independently verified cases (p = .13). Of the cytomorphologic subgroups, basaloid SUMP in particular was more likely to be benign on resection when the case had been independently verified than after consensus review (p = .0082). When considering only the independently verified cases, the ROM for each subgroup was as follows: 38.7% (12/31) in oncocytic/oncocytoid, 20% (9/45) in basaloid, 33.3% (2/6) in myoepithelial, 60% (3/5) in "other", and 100% (1/1) in both mucinous and clear cell (p = .0407).

CONCLUSION

While the RON is high across all cytomorphologic subgroups of SUMP, the ROM does vary across the groups, with basaloid cytomorphology having the lowest ROM. This effect is seen in independently verified cases but not in cases having undergone consensus review.

How the Milan System for Reporting Salivary Gland Cytopathology works in cytopathology practice: Meta-analysis of prospective studies and comparison with retrospective studies

BACKGROUND

The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) is widely accepted and endorsed by professional societies. Although several studies focusing on the MSRSGC have been published, few have been prospective studies. The objective of this study was to evaluate the effectiveness of the MSRSGC in cytopathology practice.

METHODS

A comprehensive literature search was conducted to identify all prospective studies on the MSRSGC. The risk of malignancy (ROM), risk of neoplasm, and diagnostic accuracy for each diagnostic category were calculated. Data were tabulated in Microsoft Excel, and analyses were performed with the Open Meta-Analyst program.

RESULTS

Seven prospective and seven retrospective studies were identified. The total number of fine-needle aspirations (FNAs) was 1587 in the prospective studies and 1764 in the retrospective studies. The ROM values for the nondiagnostic, nonneoplastic, atypia of undetermined significance, benign neoplasm, salivary gland neoplasm of uncertain malignant potential, suspicious for malignancy, and malignant categories in prospective versus retrospective studies were 21.0% versus 26.6%, 9.4% versus 8.1%, 34.9% versus 39.6%, 2.4% versus 2.1%, 36.6% versus 31.2%, 86.0% versus 66.0%, and 97.0% versus 96.7%, respectively. Sensitivities, specificities, and diagnostic odds ratios were 83.1% (95% confidence interval [CI], 71.1%-90.8%) versus 89.1% (95% CI, 83.6%-92.9%), 98.4% (95% CI, 96.6%-99.3%) versus 94.9% (95% CI, 91.9%-96.9%), and 310.7 (95% CI, 121.2-796.6) versus 218.8 (95% CI, 107.3-438.1).

CONCLUSIONS

This meta-analysis indicated that the MSRSGC works well in FNA cytopathology practice and improves diagnostic accuracy in all diagnostic categories. The ROMs of prospective studies were in concordance with the MSRSGC reference values.

Application of the Milan System of reporting salivary gland cytopathology and assessing its use as a risk stratification tool

INTRODUCTION

The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) was proposed by American Society of Cytopathology and International Academy of Cytology to standardize reporting system ensuring uniformity and better communication between clinicians and cytopathologists.

AIMS AND OBJECTIVES

1. To categorize salivary lesions as per MSRSGC. 2. To establish diagnostic accuracy of MSRSGC and calculate risk of malignancy for each diagnostic category.

MATERIALS AND METHODS

An ambispective study was conducted over 5 years including 45 FNAC cases of salivary lesions. The cases were categorized according to Milan System, and diagnostic accuracy of MSRSGC was established. Risk of malignancy for each category was calculated.

RESULTS

The patients' age ranged from 13 to 77 years with maximum swellings in parotid (53.3%) followed by submandibular (15.6%) and submental (2.2%). Histopathological follow-up was done in all cases. The number of cases in each category was as follows: category I: 03 (6.7%), category II: 06 (13.3%), category III: 4 (8.9%), category IVA: 25 (55.6%), category IVB: 04 (8.9%), category V: 02 (4.4%), and category VI: 01 (2.2%). The calculated ROM was as follows: category I: 0%, category II: 0%, category III: 0% category IVA: 8.0%, category IVB: 25%, category V: 50%, and category VI: 100%. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy with (without) indeterminate categories for malignancy were 88.9%(96.9), 66.7%(50.0), 94.1%(94.1), 50.0%(66.7), and 85.7%(91.9), respectively.

CONCLUSION

MSRSGC is an effective and standardized reporting system for categorization and risk stratification of salivary swellings which helps in enhancing patient care.

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.

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 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.

Cytologic diagnosis of parotid gland Warthin tumor: Systematic review and meta-analysis

It is important to define the accuracy of fine‐needle aspiration cytology (FNAC) in the diagnosis of Warthin tumor (WT). This systematic review and meta‐analysis evaluated the accuracy of FNAC in the diagnosis of WT in the parotid gland and WT growth rate. For determination of FNAC accuracy, 17 studies, encompassing 1710 cases, were included. Pulled random model estimates of sensitivity, specificity, PPV, and NPV were 93.7% (95%CI: 92.1, 95.3), 97.9% (95%CI: 97, 98.9), 93.3% (95%CI: 91.5, 95.1), and 97.4% (95%CI: 96.4, 98.4), respectively. FNAC is highly reliable for the diagnosis of WT of the parotid. The high PPV value suggests that patients with a cytological diagnosis of WT of the parotid may be assigned to active surveillance.