The utility of the Milan System as a risk stratification tool for salivary gland fine needle aspiration cytology specimens

Abstract

Objective: To perform a retrospective investigation of our institutional experience with salivary gland fine needle aspirations (FNA) through the framework of The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) and assess the risks of neoplasm and malignancy for each diagnostic category.were retrospectively categorised according to the MSRSGC. When available, preoperative cytological results were correlated with subsequent histological follow-up. Results: In total, 893 FNAs were reviewed. The specimens were retrospectively classified as nondiagnostic (ND: 13.5%), non-neoplastic (NN: 16.1%), atypia of undetermined significance (AUS: 10.8%), benign neoplasm (BN: 34.9%), salivary gland neoplasm of uncertain malignant potential (SUMP: 8.2%), suspicious for malignancy (SM: 2.7%) and malignant (M: 13.8%). Histological follow-up was available for 429 cases (48%); the majority (68.1%) were benign. The risks of neoplasm and malignancy for each category were as follows: ND: 64.5%, 16.1%; NN: 42.9%, 17.9%; AUS: 79.6%, 30.6%; BN: 100%, 2.2%; SUMP: 100%, 46.6%; SM: 94.7%, 78.9%; and M: 100%, 98.5%. Conclusions: The MSRSGC is a useful classification scheme for stratifying salivary gland lesions according to their associated risk of malignancy and guiding clinicians toward appropriate management. Diagnostic pitfalls are seen in a small proportion of cases and a multidisciplinary approach for assessing salivary gland pathology is essential in their evaluation. K E Y W O R D S cytology, fine needle aspiration, Milan system, risk of malignancy, salivary gland 1 | INTRODUCTION Fine needle aspiration (FNA) is a well established, cost-effective, and minimally invasive diagnostic tool for sampling salivary gland lesions. 1,2FNA cytology can be useful for distinguishing between non-neoplastic and neoplastic entities. 3 However, due to intratumoral heterogeneity and frequent overlapping cytomorphological features between many tumours, precise subtyping of neoplasms can be challenging. 4-7 This distinction is important as the treatment options vary across the spectrum of salivary gland pathologies. Non-neoplastic lesions can be managed conservatively, whereas a neoplastic diagnosis warrants surgical excision-in most cases with extensive surgery for high-grade malignancies, lymph node dissection for metastases and a haematology-oncology referral for haematological malignancies. Hence, cytological diagnoses that are descriptive without proper categorisation can be confusing for clinicians who need more definitive diagnoses to guide their management decisions. 8Until recently, there has been a lack of a uniform reporting scheme for cataloguing salivary gland lesions. It is in this setting that an international panel of experts under the joint efforts of the American

A retrospective comparison of salivary gland fine needle aspiration reporting with the Milan system for reporting salivary gland cytology

“…Our ROM findings are largely comparable to other such studies recently published in the literature, which report similar findings (Table including that of a large meta‐analysis of 92 studies. The calculated ROMs in our cohort appear to be on a par with those found in similar salivary gland studies in the current literature.…”

A 4-Year Retrospective Analysis of Salivary Gland Cytopathology Using the Milan System for Reporting Salivary Gland Cytology and Ancillary Studies

“…Indeed, PA and Warthin's tumours were the most frequent diagnoses (respectively 27.1% and 16.8% of total cases). This is consistent with the frequency reported in the literature [9,10,14,15]. These diagnoses are indeed straightforward for representative samples.…”

“…The three other cases which were suspicious for epithelial malignancy were finally diagnosed as non-neoplastic (myofibroblastic granuloma) or benign neoplasm (two PA). Though, the ROM for SM is consistent with the MSRSGC (68.8% vs. 60%) and with the literature (68,8% vs. 79%, 59%, 58%) [9,11,16].…”

“…A high proportion (25.6%) of cases were considered ND. This is somewhat higher than that reported in other studies by [4,[7][8][9][10][11]. This may be related to the method of sample collection.…”

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 …”