MSRSGC: A prospective study of heterogenous group atypia of undetermined significance

: Many standard books, literatures, and internet described the characteristic lineament of each salivary gland lesion. Nevertheless, there are dozens of disarray, confusion, and unmanageable morphological features regarding proper reporting. To fight with these issues, Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) was introduced in 2018, but still the third category, Atypia of undetermined significance (AUS), poses difficulties for the pathologists and clinicians for a definite interpretation.

: The aim is to analyze the risk of neoplasia (RON) and risk of malignancy (ROM) of Milan's category III (AUS) by subdividing into six groups based on cytolomorphology.

:The duration of study was from March 2018 to may 2021 with the focus on ROM and RON of all Milan's categories with especial attention on AUS.

: Result of total 329 Fine Needle Aspiration Cytology of salivary glands was categorized according to MSRSGC. On the basis of cytomorphology, further subtyping of AUS and its cytohistopathology correlation was done. The ROM and RON of each subtype was analyzed.

All data were calculated by existing formulas.

Out of 329 aspirates, 24 (07.29%) cases belong to AUS with availability of histology in 13 (54.17%) cases. RON and ROM was 84.62% and 53.85%, respectively. Cases of lymphocytes with nuclear atypia (L-NA) was the most prevalent (29.17%). The RON were 60.00%, 68.57,% 84.62%, 94.87%, 87.50%, 100%, 100% and the ROM were 20.00%, 11.42%, 53.85%, 05.13%, 43.75%, 83.33% and 100% in each Milan's categories I, II, III, IVa, IVb, V, and VI, respectively. ROM was the highest in cystic fluid with nuclear atypia (C-NA) (100.0%), followed by basaloid cells (75%), L-NA (66.675), and SC (50%), but ROM was zero in NA and oncocytic cells.

Subgrouping of AUS helps to dissipate the muddiness and provide more exact and reproducible diagnostic and prognostic tool.