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

Abstract

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 fineneedle 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.

Risk assessment of salivary gland cytological categories of the milan system: a retrospective cytomorphological and immunocytochemical institutional study

“…In the present work, the cause of ROM in the benign neoplasm category was attributed to the presence of a case of low grade epithelial myoepithelial carcinoma on surgical follow-up that was cytologically misinterpreted as pleomorphic adenoma (false negative case). The reported ROM in other studies is caused by false negative interpretation predominantly of carcinoma ex pleomorphic adenoma (1,2) followed by low grade mucoepidermoid carcinoma (13,14), adenoid cystic carcinoma (9,14), epithelial myoepithelial carcinoma (14) and oncocytic carcinoma (13). Epithelial myoepithelial carcinoma can pose a diagnostic complexity to the cytopathologist.…”

“…Rossi et al (7) reported an allowed range of 10% to 15% for this category's incidence. However in some reports, the rate reached up to 44% (12) or 50 % (9). The cause of these wide variations in the incidence of the non-diagnostic category between different studies might be related to the fact that the adequacy of FNA materials of the salivary gland lesions had no definite criteria and was widely related to variable quantitative and qualitative restrictions for a long period of time.…”

Cytopathology and diagnostics of Warthin's tumour

“…Results of several studies that analysed distribution of cases and estimated ROM in each MSRSGC category show that FNA cytology is an effective diagnostic procedure and confirmed the validity and diagnostic utility of MSRSGC, further revealing that ROMs of each category were broadly in line with those suggested in MSRSGC. In some of these studies, higher ROM for AUS category than in MSRSGC was observed, which probably resulted from the lower number or heterogeneity of AUS patients in these studies …”

“…Moreover, as presented in reports listed in Table and other studies in the literature, a, small number of WT cases, especially WT metaplastic variant with mild or marked nuclear atypia of cells, can be defined as other MSRSGC diagnostic categories . Thus, WTs with mild or marked nuclear atypia of cells could be classified as category 3—AUS with 20% ROM, as category 4B—salivary gland neoplasm of uncertain malignant potential with 35% ROM, as category 5—suspicious for malignancy with 60% ROM for finding a malignant tumour by histology, or even as category 6—malignant (Table ) .…”

Serous cavity fluids: Momentum, molecules, markers… and more!

“…The field of cytopathology successfully implemented standardized reporting with the initial version of the Bethesda System for Reporting Cervical Cytology over 20 years ago and its subsequent updates . Updated terminology reporting systems have also been introduced for cytologic sample reporting in the thyroid, pancreas, urine, salivary gland, and breast as well . As we enter a new decade, the latest effort for improving reporting has gained momentum to incorporate serous fluids in a standardized format .…”