TY - BOOK
T1 - The Milan System for Reporting Salivary Gland Cytopathology
T2 - Indeterminate Categories and Meta-Analysis
AU - Lagerstam, Henri
PY - 2025
Y1 - 2025
N2 - The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) was
introduced in 2018 to overcome the absence of a coherent
standardisation terminology system for salivary gland fine-needle
aspirations (SG-FNA). The cytopathology of salivary gland lesions is
challenged by the low number of tumours and the high heterogeneity of
these tumours. In addition, there is a great variety of
cytomorphological overlaps between non-neoplastic and neoplastic
lesions, especially between benign and low-grade malignant tumours. Most
of these tumours with overlapping features are categorised into atypia
of undetermined significance (AUS) and salivary gland neoplasms of
uncertain malignant potential (SUMP) MSRSGC categories.
In this thesis, we evaluated how the MSRSGC performs in real-life
diagnostic practice. We performed a comprehensive literature search to
find all prospective studies published on the MSRSGC to evaluate its
daily performance in laboratory practice. We assessed the AUS and SUMP
categories at our institution during a five- year period, including the
COVID-19 pandemic years and additional analyses of the impact of sex and
age. We also investigated the speed of laboratory workflows and patient
management. Finally, we evaluated the performance and diagnostic
pitfalls of the MSRSGC in diagnosing Warthin’s tumour (WT), the second
most common salivary gland tumour.
We can conclude that the MSRSGC works well in daily cytopathology
practice. Its diagnostic accuracy is high. The risk of malignancy (ROM)
in prospective studies corroborated the MSRSGC’s reference values. In
our institutional analysis, the ROMs in the AUS and SUMP categories were
lower than the reference values. There was a variance in the ROM
between years, probably due to the COVID-19 pandemic. In the age and sex
analysis, males and 30–69-year-olds had the highest risk of malignancy.
Moreover, WT was found to be the most common histological follow-up
in the AUS category and the second most common in the SUMP category in
our series. The reasons for the AUS categorisation instead of the benign
neoplasm category were the absence of papillae in the cell block
specimen, the lack of cystic degeneration and the presence of small
groups of oncocytes. WT cases with more suspicious features of
malignancy were placed into the SUMP category. Features that increased
suspicion were necrosis, diffuse hypercellularity and oncocytoid cells.
The SUMP diagnosis led to surgical management faster than the AUS
diagnosis, as recommended by the MSRSGC. There were differences in
laboratory workflows between years that were perhaps influenced by the
COVID-19 pandemic. Generally, laboratory workflow and patient management
were quite quick, and the MSRSGC improves risk stratification and
communication between cytopathologists and clinicians.
AB - The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) was
introduced in 2018 to overcome the absence of a coherent
standardisation terminology system for salivary gland fine-needle
aspirations (SG-FNA). The cytopathology of salivary gland lesions is
challenged by the low number of tumours and the high heterogeneity of
these tumours. In addition, there is a great variety of
cytomorphological overlaps between non-neoplastic and neoplastic
lesions, especially between benign and low-grade malignant tumours. Most
of these tumours with overlapping features are categorised into atypia
of undetermined significance (AUS) and salivary gland neoplasms of
uncertain malignant potential (SUMP) MSRSGC categories.
In this thesis, we evaluated how the MSRSGC performs in real-life
diagnostic practice. We performed a comprehensive literature search to
find all prospective studies published on the MSRSGC to evaluate its
daily performance in laboratory practice. We assessed the AUS and SUMP
categories at our institution during a five- year period, including the
COVID-19 pandemic years and additional analyses of the impact of sex and
age. We also investigated the speed of laboratory workflows and patient
management. Finally, we evaluated the performance and diagnostic
pitfalls of the MSRSGC in diagnosing Warthin’s tumour (WT), the second
most common salivary gland tumour.
We can conclude that the MSRSGC works well in daily cytopathology
practice. Its diagnostic accuracy is high. The risk of malignancy (ROM)
in prospective studies corroborated the MSRSGC’s reference values. In
our institutional analysis, the ROMs in the AUS and SUMP categories were
lower than the reference values. There was a variance in the ROM
between years, probably due to the COVID-19 pandemic. In the age and sex
analysis, males and 30–69-year-olds had the highest risk of malignancy.
Moreover, WT was found to be the most common histological follow-up
in the AUS category and the second most common in the SUMP category in
our series. The reasons for the AUS categorisation instead of the benign
neoplasm category were the absence of papillae in the cell block
specimen, the lack of cystic degeneration and the presence of small
groups of oncocytes. WT cases with more suspicious features of
malignancy were placed into the SUMP category. Features that increased
suspicion were necrosis, diffuse hypercellularity and oncocytoid cells.
The SUMP diagnosis led to surgical management faster than the AUS
diagnosis, as recommended by the MSRSGC. There were differences in
laboratory workflows between years that were perhaps influenced by the
COVID-19 pandemic. Generally, laboratory workflow and patient management
were quite quick, and the MSRSGC improves risk stratification and
communication between cytopathologists and clinicians.
M3 - Doctoral thesis
SN - 978-952-03-3987-6
T3 - Tampere University Dissertations - Tampereen yliopiston väitöskirjat
BT - The Milan System for Reporting Salivary Gland Cytopathology
PB - Tampere University
ER -