Utility of the Milan system for reporting salivary gland cytopathology: A retrospective 5 years study

Does Milan affect management? A retrospective analysis of resection rate and time to surgery among Milan categories

INTRODUCTION

The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) is an established system with reproducible risk of malignancies (ROM) for salivary gland fine needle aspiration (SGFNA). No studies have reviewed the relationship between Milan categories and the resection rate (RR) and time to resection (TTR).

METHODS

We searched our database (January 1, 2011 to January 4, 2021) for non-lymphoma SGFNAs and assigned appropriate MSRSGC categories. RR and TTR were calculated and compared for each category. A literature search was performed; RRs and TTRs were compared.

RESULTS

Seven hundred and eighty SGFNAs were identified, 333 with follow-up. RR was highest in suspicious for malignancy (SUS, V; 70.6%, n = 12/17), followed by the salivary gland neoplasm of uncertain malignant potential (SUMP, IVb; 69.6%, n = 80/115) and malignant (M, VI; 55.6%, n = 75/135). Among M, primary tumors had a higher RR (65.1%, n = 41/63) than metastases (47.2%, n = 34/72, p = .36). In literature review, SUS had the highest RR (69.3%, n = 233/336) followed by M (61.6%, n = 821/1332) and SUMP (60.2%, n = 632/1050). TTR was shorter in SUS (mean = 32.3 days, median = 25 days). Within the benign neoplasms (BN, IVa), Pleomorphic adenomas (PAs) had a higher RR than Warthin tumors (WTs) (66.3% vs. 37.2%, p < .00001), and a shorter TTR (median = 63 days vs. 90 days).

CONCLUSIONS

Tumors classified as SUS had higher RR and at shorter intervals than those classified as SUMP. PAs have higher RRs and more expedient surgery than WTs. Cases classified as M are less likely to undergo follow-up than SUS, perhaps due to a lower RR for metastases.

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.