Application of the Milan System for Reporting Salivary Gland Cytopathology in pediatric patients: An international, multi‐institutional study

Abstract

BACKGROUND Pediatric salivary gland fine‐needle aspiration (FNA) is uncommon with a higher frequency of inflammatory lesions and a small proportion of malignancies. This international, multi‐institutional cohort evaluated the application of the Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) and the risk of malignancy (ROM) for each diagnostic category. METHODS Pediatric (0‐ to 21‐year‐old) salivary gland FNA specimens from 22 international institutions of 7 countries, including the United States, England, Italy, Greece, Finland, Brazil, and France, 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. Cytology‐histology correlation was performed where available, and the ROM was calculated for each MSRSGC diagnostic category. RESULTS The cohort of 477 aspirates was reclassified according to the MSRSGC as follows: nondiagnostic, 10.3%; nonneoplastic, 34.6%; AUS, 5.2%; benign neoplasm, 27.5%; SUMP, 7.5%; SM, 2.5%; and malignant, 12.4%. Histopathologic follow‐up was available for 237 cases (49.7%). The ROMs were as follows: nondiagnostic, 5.9%; nonneoplastic, 9.1%; AUS, 35.7%; benign neoplasm, 3.3%; SUMP, 31.8%; SM, 100%; and malignant, 100%. Mucoepidermoid carcinoma was the most common malignancy (18 of 237; 7.6%), and it was followed by acinic cell carcinoma (16 of 237; 6.8%). Pleomorphic adenoma was the most common benign neoplasm (95 of 237; 40.1%). CONCLUSIONS The MSRSGC can be reliably applied to pediatric salivary gland FNA. The ROM of each MSRSGC category in pediatric salivary gland FNA is relatively similar to the ROM of each category in adult salivary gland FNA, although the reported rates for the different MSRSGC categories are variable across institutions.

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

“…When data extracted from all nonpediatric studies were combined, the mean ROM for nondiagnostic category was 15%, a rate lower than that originally estimated by MSRSGC and yet substantially higher than that observed in our pediatric cohort. Again, the relatively small numbers of cases in our cohort and other pediatric series 15,16 have limited the statistic power. Nonetheless, the observed minimal or low malignancy risk in nondiagnostic cases in children may have important implications for clinical management and therefore merits further investigation with greater number of patients from different institutions.…”

“…Similar findings were also reported in another pediatric series by Satturwar et al 15 that included 32 salivary gland FNAs. In a recent international, multi‐institutional pediatric series by Maleki et al, 16 the ROM for nondiagnostic category was 5.9% (1 of 17 cases). In contrast to this low malignancy risk, MSRSGC estimates the general ROM in nondiagnostic aspirates to be approximately 25% and recommends repeat FNA, imaging studies such as contrast‐enhanced CT/MRI, alternative biopsy approaches, or surgery 18 .…”

“…Recent studies in pediatric patients, although limited by scale, also support MSRSGC as a valuable tool for the preoperative assessment of salivary gland lesions in children. 6,15,16 However, a significant fraction of salivary gland aspirates may provide nondiagnostic results. In a meta-analysis by Jalaly et al, 17 the overall rate of nondiagnostic samples was 10%.…”

“…Since the introduction of the Milan system for reporting salivary gland cytopathology (MSRSGC) in 2018, its clinical utility for standardization of reporting and preoperative risk stratification has been widely validated in adults. Recent studies in pediatric patients, although limited by scale, also support MSRSGC as a valuable tool for the preoperative assessment of salivary gland lesions in children 6,15,16 . However, a significant fraction of salivary gland aspirates may provide nondiagnostic results.…”

Rapid on‐site evaluation improves diagnostic performance of fine‐needle aspiration cytology for salivary lesions: Comparison of data from two cancer centers in southern China

“…3 A wide range of ROM has been reported regarding AUS (17.0%-37.5%) and SUMP (24.6%-62.0%). 24,[26][27][28][29][30][31][32][33][34] It is recommended that AUS cases should undergo repeat FNAC or surgery, and surgery should be considered for patients with SUMP category because of their high ROM. Fortunately, distribution of these two categories are relatively lower than the other categories.…”