Application of the Milan system for reporting risk stratification in salivary gland cytopathology

Update on Salivary Gland Fine-Needle Aspiration and the Milan System for Reporting Salivary Gland Cytopathology

CONTEXT.—

Fine-needle aspiration (FNA) is a well-established procedure for the diagnosis and management of salivary gland lesions, despite challenges imposed by salivary gland tumor diversity, complexity, and cytomorphologic overlap. Until recently, the reporting of salivary gland FNA specimens was inconsistent among different institutions throughout the world, leading to diagnostic confusion among pathologists and clinicians. In 2015, an international group of pathologists initiated the development of an evidence-based tiered classification system for reporting salivary gland FNA specimens, the Milan System for Reporting Salivary Gland Cytopathology (MSRSGC). The MSRSGC consists of 6 diagnostic categories, which incorporate the morphologic heterogeneity and overlap among various nonneoplastic, benign, and malignant lesions of the salivary glands. In addition, each MSRSGC diagnostic category is associated with a risk of malignancy and management recommendations.

OBJECTIVE.—

To review the current status of salivary gland FNA, core needle biopsies, ancillary studies, and the beneficial role of the MSRSGC in providing a framework for reporting salivary gland lesions and guiding clinical management.

DATA SOURCES.—

Literature review and personal institutional experience.

CONCLUSIONS.—

The main goal of the MSRSGC is to improve communication between cytopathologists and treating clinicians, while also facilitating cytologic-histologic correlation, quality improvement, and research. Since its implementation, the MSRSGC has gained international acceptance as a tool to improve reporting standards and consistency in this complex diagnostic area, and it has been endorsed by the 2021 American Society of Clinical Oncology management guidelines for salivary gland cancer. The large amount of data from published studies using MSRSGC served as a basis for the recent update of the MSRSGC.

Second edition of the Milan System for Reporting Salivary Gland Cytopathology: Refining the role of salivary gland FNA

The use of standardised reporting systems for non-gynaecologic cytopathology has made enormous gains in popularity during the past decade, including for thyroid fine-needle aspiration, urine cytology, serous effusions, pancreas, lymph nodes, lung and more. In February 2018, the first edition of the Atlas of the Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) was published. The MSRSGC defines six diagnostic fine-needle aspiration categories encompassing the spectrum of non-neoplastic, benign and malignant lesions of the salivary glands. The goal of the MSRSGC is to combine each diagnostic category with a defined risk of malignancy and a specific clinical and/or surgical management algorithm. Since its initial publication in 2018, more than 200 studies and commentaries have been published, confirming the role of the MSRSGC. The second edition of the MSRSGC, published in July 2023, includes refined risks of malignancy based on systematic reviews and meta-analyses, a new chapter summarising the use of salivary gland imaging, new advances in ancillary testing and updates in nomenclature.

Pitfalls in Salivary Gland Cytology

BACKGROUND

Salivary gland lesions possess diagnostic challenges on fine-needle aspiration (FNA) material. They are relatively uncommon, yet present with a wide spectrum of cytomorphology. Herein, we review common salivary gland neoplasms, their cytomorphologic features, their diagnostic pitfalls, and ancillary studies helpful in achieving an accurate diagnosis.

SUMMARY

There are many cytomorphologic overlaps between benign and malignant salivary gland entities. Moreover, metaplasia, cystic changes, and degenerative changes are common findings adding to diagnostic dilemmas. These complicating factors contribute to a minute risk of malignancy in salivary gland lesions that are interpreted as benign on FNA. In rare cases, even malignant salivary gland neoplasms are misinterpreted as benign on aspirated material due to the many cytomorphologic overlaps. For example, benign and malignant neoplasms containing stroma such as myoepithelioma and adenoid cystic carcinoma may be misinterpreted as pleomorphic adenoma. Moreover, diagnosis of salivary gland neoplasms with basal cell features can be confusing on FNA materials; for example, basal cell adenoma can be misinterpreted as adenoid cystic carcinoma. Mucoepidermoid carcinomas have many different appearances on aspirated material due to variable amounts of mucin, degree of nuclear atypia, cellular content, and squamous metaplasia. Acinic cell carcinoma exhibits large cells with abundant cytoplasm on FNA, which can be mistaken for oncocytic cells in oncocytoma or Warthin tumor. Salivary duct carcinoma shows distinct features of malignancy and thus can be mistaken for secondary tumors involving the salivary glands or other malignant salivary gland tumors. The presence of tumor-associated lymphocytes is another underlying cause of misdiagnosis, especially when considering the differential diagnosis of an intraparotid lymph node. Ancillary studies such as immunohistochemistry and molecular studies are gaining more attention to be utilized on FNA cases. PLAG1 immunostaining, CD117, DOG1, mammaglobin, and androgen receptor (AR) are examples of commonly used immunostains in diagnosis of salivary gland lesions. MYB gene fusion, rearrangements of the MAML2 gene, and ERBB2/HER2 are examples of molecular alterations useful in diagnosis of salivary gland neoplasms. In conclusion, the aim of salivary gland cytology is to differentiate benign entities from the malignant ones and to prevent unnecessary aggressive treatments.

KEY MESSAGES

The diagnostic pitfalls are enormous in salivary gland cytology. Familiarity with cytomorphology of different entities and their cytomorphologic overlaps, and application of ancillary studies improves the diagnostic yield, patient management and prevents unnecessary aggressive procedures.

The Milan System for Reporting Salivary Gland Cytopathology: the experience of a tertiary cancer center with emphasis on non-mucinous cysts and improving diagnostic results

INTRODUCTION

The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) was introduced in 2018 to standardize cytology reporting and guide patient treatment. We aimed to evaluate the utility of this system applied to patients at our cancer center.

MATERIALS AND METHODS

We retrospectively reviewed cases of salivary gland fine-needle aspirations (FNAs) performed in our institution (2019-2022). All were performed by radiologists and immediately assessed for specimen adequacy. The cytologic findings were classified into the MSRSGC except for non-mucinous cystic contents (NMCC) where the lesion was radiologically consistent with a cyst and totally collapsed after FNA. Such lesions were categorized as non-neoplastic (NN) instead of non-diagnostic (ND). The cytologic findings were compared to corresponding histologic findings (212 available cases), and the risk of malignancy was calculated.

RESULTS

Five hundred five FNAs were categorized as: 25 (4.95%) ND; 86 (17.03%) NN, of which 39 were NMCC; 9 (1.78%) atypia of undetermined significance; 138 (27.33%) benign neoplasms; 57 (11.29%) salivary gland neoplasm of undetermined malignant potential; 16 (3.17%) suspicious for malignancy; and 174 (34.46%) malignant. The risk of malignancy rates for the following categories were: ND, 40%; NN, 25%; atypia of undetermined significance, 0%; benign neoplasms, 1%; salivary gland neoplasm of undetermined malignant potential, 54.54%; suspicious for malignancy, 90.9%; and malignant, 100%. Thirty-one NMCC with available follow-up resolved/remained stable.

CONCLUSIONS

Our results validate the reproducibility of the MSRSGC applied in our cancer center. Based on the benign course of cysts with NMCC, we propose that such cases be categorized as NN, provided the cyst is totally resolved after FNA.

Second edition of the Milan System for Reporting Salivary Gland Cytopathology: Refining the role of salivary gland FNA

The use of standardized reporting systems for nongynecologic cytopathology has made enormous gains in popularity during the past decade, including for thyroid fine-needle aspiration, urine cytology, serous effusions, pancreas, lymph nodes, lung, and more. In February 2018, the first edition Atlas of the Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) was published. The MSRSGC defines six diagnostic fine-needle aspiration categories encompassing the spectrum of Non-Neoplastic, benign, and malignant lesions of the salivary glands. The goal of the MSRSGC is to combine each diagnostic category with a defined risk of malignancy and a specific clinical and/or surgical management algorithm. Since its initial publication in 2018, more than 200 studies and commentaries have been published confirming the role of the MSRSGC. The second edition of the MSRSGC, published in July 2023, includes refined risks of malignancy based on systematic reviews and meta-analyses, a new chapter summarizing the use of salivary gland imaging, new advances in ancillary testing, and updates in nomenclature. CONCISE SENTENCE: The second edition of the Milan System for Reporting Salivary Gland Cytopathology, published in July 2023, includes refined risks of malignancy based on systematic reviews and meta-analyses, a new chapter summarizing the use of salivary gland imaging, new advances in ancillary testing, updates in nomenclature, and a guide to the practical application of the latest ancillary markers for the diagnosis of selected salivary gland fine-needle aspiration cases.

Second edition of the Milan System for Reporting Salivary Gland Cytopathology: Refining the role of salivary gland FNA

The use of standardized reporting systems for non-gynecologic cytopathology has made enormous gains in popularity during the past decade, including for thyroid fine-needle aspiration, urine cytology, serous effusions, pancreas, lymph nodes, lung, and more. In February 2018, the first edition Atlas of the Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) was published. The MSRSGC defines six diagnostic fine-needle aspiration categories encompassing the spectrum of non-neoplastic, benign, and malignant lesions of the salivary glands. The goal of the MSRSGC is to combine each diagnostic category with a defined risk of malignancy and a specific clinical and/or surgical management algorithm. Since its initial publication in 2018, more than 200 studies and commentaries have been published confirming the role of the MSRSGC. The second edition of the MSRSGC, published in July 2023, includes refined risks of malignancy based on systematic reviews and meta-analyses, a new chapter summarizing the use of salivary gland imaging, new advances in ancillary testing, and updates in nomenclature.

The protective role of postoperative radiation therapy in low and intermediate grade major salivary gland malignancies: A study of the Canadian Head and Neck Collaborative Research Initiative

BACKGROUND

The objective of this study was to examine the utility of postoperative radiation for low and intermediate grade cancers of the parotid and submandibular glands.

METHODS

The authors conducted a retrospective, Canadian-led, international, multi-institutional analysis of a patient cohort with low or intermediate grade salivary gland cancer of the parotid or submandibular gland who were treated from 2010 until 2020 with or without postoperative radiation therapy. A multivariable, marginal Cox proportional hazards regression analysis was performed to quantify the association between locoregional recurrence (LRR) and receipt of postoperative radiation therapy while accounting for patient-level factors and the clustering of patients by institution.

RESULTS

In total, 621 patients across 14 tertiary care centers were included in the study; of these, 309 patients (49.8%) received postoperative radiation therapy. Tumor histologies included 182 (29.3%) acinic cell carcinomas, 312 (50.2%) mucoepidermoid carcinomas, and 137 (20.5%) other low or intermediate grade primary salivary gland carcinomas. Kaplan-Meier LRR-free survival at 10 years was 89.0% (95% confidence interval [CI], 84.9%-93.3%). In multivariable Cox regression analysis, postoperative radiation therapy was independently associated with a lower hazard of LRR (adjusted hazard ratio, 0.53; 95% CI, 0.29-0.97). The multivariable model estimated that the marginal probability of LRR within 10 years was 15.4% without radiation and 8.8% with radiation. The number needed to treat was 16 patients (95% CI, 14-18 patients). Radiation therapy had no benefit in patients who had early stage, low-grade salivary gland cancer without evidence of nodal disease and negative margins.

CONCLUSIONS

Postoperative radiation therapy may reduce LLR in some low and intermediate grade salivary gland cancers with adverse features, but it had no benefit in patients who had early stage, low-grade salivary gland cancer with negative margins.

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

BACKGROUND

Fine-needle aspiration (FNA) results classified as the nondiagnostic category of the Milan system for reporting salivary gland cytopathology (MSRSGC) may be infrequently encountered in children. Clinical management may be challenging due to lack of data regarding outcomes and underlying causes.

METHODS

We retrospectively analyzed 106 consecutive pediatric salivary gland FNAs (2000-2020; 45% performed under image guidance). The outcomes of patients with nondiagnostic results were analyzed. Clinical parameters, FNA procedural parameters, and histopathologic parameters were compared between diagnostic and nondiagnostic cases. A root cause analysis was performed using the fishbone diagram and the 5 Whys method.

RESULTS

A total of 103 initial FNAs were identified. The nondiagnostic rates for initial and repeat biopsy were 16% (16/103) and 67% (2/3), respectively. Initial nondiagnostic FNAs were most frequently managed by clinical/radiologic follow-up only (56%, 9/16), followed by direct surgery (19%, 3/16) and repeat FNA (19%, 3/16). By histologic and clinical/radiologic follow-up, the risk of malignancy for nondiagnostic cases was zero. Palpation guidance (P < .05), inadequate sampling determined by rapid on-site evaluation (P < .01), and lesions with cystic, vascular, or diffuse nature (P < .05) were significantly associated with nondiagnostic results. By root cause analysis, proceduralist sampling error and lack of ultrasound guidance were the most common primary and secondary causes, respectively.

CONCLUSIONS

Pediatric salivary gland lesions of the nondiagnostic MSRSGC category have minimal risk of malignancy and may be successfully managed by clinical/radiologic follow-up. The root causes for nondiagnostic results were often multifactorial and primarily related to proceduralist sampling, characteristics of the lesions, and lack of ultrasound guidance.

Application of the Milan system for reporting salivary gland cytopathology using cell blocks

The Milan system for reporting salivary gland cytopathology (MSRSGC) is a novel standardized classification tool for salivary gland cytology specimens based on the use of direct smears. Formalin-fixed paraffin-embedded (FFPE) cell blocks facilitate the use of ancillary studies, leading to improved diagnostic accuracy. However, the application of the MSRSGC with only cell blocks has not been well established. Consecutive cohort of all parotid gland cytology specimens between 01/01/2018 and 30/06/2021 was performed. All cytology specimens were processed into cell blocks only. Cytologic diagnoses were classified prospectively according to the MSRSGC categories. The risk of malignancy (ROM) for each diagnostic category and the diagnostic performance were calculated. A total of 230 FNA samples from 221 patients were identified, including 47% and 78.4% with surgical or clinical follow-up, respectively. The ROMs based on surgical follow-up for the non-diagnostic, non-neoplastic, AUS, neoplasm: benign, SUMP, SFM and malignant categories were 21.4%,0%,50%,0%,30%,100% and 100%, respectively. The ROMs based on the clinical follow-up for these categories were 7.3%,0%,37.3%,0%,27.3%,100% and 100%, respectively. Following surgical excision, all Milan IVa category samples were confirmed as benign, and all Milan V and VI category samples were confirmed as malignant. This study validates the application of the MSRSGC with the sole use of FFPE cell blocks. The diagnostic accuracy of MSRSGC is high and compares favorably to other institutions using traditional cytology assessment methods. Furthermore, FNA results using this technique enabled to provide optimal patient management based on the ROM of the different Milan system categories.

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

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.

Development of head and neck pathology in Europe

This review gives a brief history of the development of head and neck pathology in Europe from a humble beginning in the 1930s to the explosive activities the last 15 years. During the decades before the introduction of immunohistochemistry in the 1980s, head and neck pathology grew as a subspeciality in many European countries. In the late 1940s, the Institute of Laryngology and Otology with its own pathology laboratory was founded in London, and in 1964 the World Health Organization (WHO) International Reference Centre for the Histological Classification of Salivary Tumours was established at the Bland-Sutton Institute of Pathology, also in London. International collaboration, and very much so in Europe, led to the publication of the first WHO Classification of Salivary Gland Tumours in 1972. In the 1960s, a salivary gland register was organised in Hamburg and in Cologne the microlaryngoscopy was invented enabling microscopic endoscopic examination and rather shortly afterwards a carbon dioxide laser attached to the microscope became established and laryngeal lesions could be treated by laser vaporisation. During the last three decades, the use of immunohistochemistry supplemented with cytogenetic and refined molecular techniques has greatly facilitated the pathological diagnostics of head and neck lesions and has had a huge impact on research. Collaboration between different European centres has drastically increased partly due to establishment of scientific societies such as the Head and Neck Working Group (HNWG) within the European Society of Pathology and the International Head and Neck Scientific Group (IHNSG). A very large number of European pathologists have contributed to the 2nd, 3rd and 4th WHO books, and are involved in the upcoming 5th edition. Accredited educational meetings and courses are nowadays regularly arranged in Europe. Numerous textbooks on head and neck pathology have been written and edited by European pathologists. The increased collaboration has created larger series of tumours for research and new entities, mainly defined by their genetic abnormalities, are continuously emerging from Europe, particularly regarding salivary gland neoplasms and "undifferentiated" sinonasal tumours. These findings have led to a better and more precise classification and open the possibilities for new treatment strategies.

Fine-Needle Aspiration Biopsy of Pediatric Salivary Gland Tumors: Analysis of Patient Tolerability, Sedation Requirement, and Procedural Complication

OBJECTIVE

Fine-needle aspiration (FNA) biopsy is the standard diagnostic tool recommended by consensus management guidelines for preoperative evaluation of salivary gland tumors in adults. However, its utility in the pediatric population remains debated due to a paucity of data and inherited challenges of pediatric management (patient cooperation, the need for sedation, and procedural complications).

METHODS

Consecutive series of 92 FNA biopsies of pediatric salivary gland lesions with available procedural data were included for retrospective analysis. Patient demographics, procedural characteristics, and complications were assessed.

RESULTS

Sixty-three patients (68%) tolerated FNA without sedation. Sedation need was significantly associated with younger age, concurrent non-FNA procedure requiring sedation, ultrasound guidance, interventional radiologist as the proceduralist, and radiology suite as the facility setting. The sedation rates for children, and early, middle, and late adolescents were 69%, 32%, 12%, and 10%, respectively, with an optimal cutoff point of ≤12 years for age derived from receiver operating characteristic curve analysis. No significant procedural complications were observed. Sedation did not provide significantly better diagnostic yield.

CONCLUSION

FNA biopsy of salivary gland tumors is safe, well tolerated by the pediatric population, and can be effectively performed in an outpatient setting without sedation in most cases. FNA biopsy is a useful tool in the preoperative management of pediatric patients with salivary gland tumors.

Application of the Milan System for Reporting Pediatric Salivary Gland Cytopathology: Analysis of histologic follow-up, risk of malignancy, and diagnostic accuracy

BACKGROUND

The diagnosis and management of salivary gland tumors in pediatric patients can be challenging. The utility of fine-needle aspiration (FNA) cytopathology and the performance of the Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) in this age group have not been systematically assessed. The paucity of data has contributed to the controversial role of FNA cytopathology in the presurgical management of these patients.

METHODS

The authors retrospectively analyzed 104 pediatric salivary gland FNAs (2000-2020). A correlation with the available histopathologic follow-up (n = 54) was performed. The distribution percentages, the risk of neoplasm (RON), and the risk of malignancy (ROM) were assessed for each category of the MSRSGC.

RESULTS

The overall sensitivity, specificity, negative predictive value, and positive predictive value of pediatric salivary gland FNAs were 80%, 97%, and 92%, respectively. The RON values for the nondiagnostic, nonneoplastic, atypia of undetermined significance, benign neoplasm, salivary gland neoplasm of uncertain malignant potential, suspicious for malignancy, and malignant categories were 60%, 11%, 100%, 100%, 100%, 100%, and 100%, respectively, whereas the ROM values were 0%, 11%, 100%, 6%, 67%, 100%, and 100%, respectively. The percentage of nonneoplastic FNAs was greater in comparison with the adult population (52% vs 8%). All neoplasms in patients aged 0 to 10 years were malignant, whereas benign neoplasms occurred only in patients aged ≥11 years; this supported an inverse correlation between age and malignancy rate in salivary gland neoplasms.

CONCLUSIONS

FNA cytopathology demonstrates excellent diagnostic performance in differentiating malignant and benign pediatric salivary gland lesions. The MSRSGC is a valuable tool for standardization of the reporting and preoperative risk stratification of these lesions.

Observation Rather than Surgery for Benign Parotid Tumors: Why, When, and How

Surgery is the preferred treatment of benign parotid lesions, but it carries a risk of complications. Therefore, the approach toward the surgery of these lesions should seek to avoid complications. There are no guidelines or recommendations for when not to operate. Integration of comorbidities and other factors shift the scales from surgery toward observation in a small subset of patients presenting with parotid tumors. When observation is chosen, the patient should be followed frequently and cautiously, and the surgeon should be prepared to change strategy to surgical excision if in doubt.

The Milan System, from Its Introduction to Its Current Adoption in the Diagnosis of Salivary Gland Cytology

Salivary gland masses are often encountered in the everyday practice of cytopathology. It is commonly known that the cytologic interpretation of these lesions can pose diagnostic problems due to overlapping cytomorphologic features. Fine needle aspiration (FNA) of salivary lesions shows good to excellent sensitivity and specificity in differentiating a neoplastic from a non-neoplastic process and in diagnosing common tumors such as pleomorphic adenoma. However, its value is limited in diagnosing specific neoplastic entities especially those with well-differentiated morphology. In light of this gap, an international group of pathologists has proposed a management-oriented, tiered classification for reporting salivary gland FNA specimens, “The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC)”. Similar to other classification systems, the MSRSGC scheme comprises six diagnostic categories, which were linked with a specific risk of malignancy (ROM) and management. In this review article, the author evaluated the published literature on FNA in diagnosing salivary gland lesions with the adoption of the Milan system since its introduction in the daily practice of salivary cytopathology.

Application of Milan system for reporting of salivary gland pathology and risk stratification: An institutional experience

Background:

Fine-needle aspiration cytology (FNAC) is a sensitive technique for diagnosing salivary gland pathologies. Milan system of reporting salivary gland cytopathology (MSRSGC) is an evidence-based system of reporting which has been introduced to improve reporting and communication between cytopathologist and clinician by introducing standardized categories with specified treatment protocols.

Aims and Objectives:

The aim of the present study is to find the diagnostic accuracy and risk of malignancy (ROM) in various categories when MSRSGC is applied.

Materials and Methods:

A single-institute-based 3-year retrospective study was done. All salivary gland lesions were reclassified according to MSRSGC. ROM, diagnostic specificity, sensitivity and accuracy of FNAC of salivary gland lesions were calculated.

Results:

A total of 133 cases were included in the study. Overall, the most common diagnosis was found to be pleomorphic adenoma comprising 61 (42.8%) of all cases. Adenoid cystic carcinoma was the most commonly diagnosed malignancy comprising of 6 (4.5%) of all lesions. Cases were further divided into Milan categories, namely nondiagnostic, nonneoplastic, atypia of undetermined significance, benign neoplasm, neoplasm of undetermined malignant potential, suspicious of malignancy and malignancy comprising 5 (3.7%), 29 (21.8%), 77 (57.8%), 4 (3%), 3 (2.2%), 1 (0.7%) and 14 (10.5%) cases, respectively, with ROM of 0, 14.28%, 33.33%, 5.71%, 66.66%, 100% and 80%, respectively. Sensitivity, specificity and diagnostic accuracy to separate benign from malignant lesions were 80%, 89.80% and 87.50%, respectively.

Conclusion:

FNAC of the salivary gland lesions is a safe and reliable diagnostic procedure. The Milan system of reporting is a risk stratification system which can improve the overall effectiveness of reporting and care of patients.

Impact of the Milan System for Reporting Salivary Gland Cytology on risk assessment when used in routine practice in a real-time setting

INTRODUCTION

Several retrospective studies across the world have validated the role of the Milan System for Reporting Salivary Gland Cytology (MSRSGC) in improving communication between pathologists and clinicians. In this study, we evaluated the applications of MSRSGC in a real-time setting for 2 years.

MATERIALS AND METHODS

All salivary gland lesions that underwent fine-needle aspiration (FNA) from January 2018 to December 2020 were categorized according to MSRSGC guidelines. The risk of malignancy (ROM) was calculated for each category and compared with the ROM proposed by MSRSGC and recent retrospective studies.

RESULTS

A total of 160 FNA of salivary gland lesions were categorized as: nondiagnostic (ND) 30 (18%), non-neoplastic (NN) 7 (10.6%), atypia of undetermined significance (AUS) 5 (3.1%), benign neoplasm (BN) 59 (36.8%), salivary gland of uncertain malignant potential (SUMP) 21 (13%), suspicious for malignancy (SM) 3 (1.84%), and malignant (M) 25 (15.6%). Histopathologic follow-up was available for 94 (57.5%) cases. The ROM for each category was ND 54%, NN 0%, AUS 66%, BN 0%, SUMP 37.56%, SM 100%, and M 100%.

CONCLUSION

With strict adherence to the diagnostic criteria and MSRSGC guidelines, a ROM of 100% in SM and M categories and a ROM of 0% in NN can be achieved in a real-time setting. The high ROM in the ND category in our study highlights the value of repeat FNA/biopsy for this category. High ROM for AUS indicates the tendency to classify high-grade tumors as AUS, calling for refinement in its criteria.

Current classification systems and standardized terminology in cytopathology

The history of classification systems and the search for a unified nomenclature in cytopathology spans several decades and expresses the preoccupation of all those involved to make cytopathology a reliable diagnostic tool and a trusted screening method. Early classification schemes, applicable to exfoliative and aspiration cytology, attempted to set some basic standards for how non-gynecological cytopathology findings should be reported. While useful in establishing some basic guidelines, these were not specific to the various fields of non-gynecologic cytopathology, often burdened with specific problems. Cytopathology has evolved tremendously in the last couple of decades, undoubtedly boosted by the emergence of various classification schemes that, more than ever, are based on evidence gathered by professionals across the globe. The benefit of classification systems and standardized nomenclature in cytopathology is to provide useful, clear, and clinically relevant information for clinicians and ultimately to provide the best patient care. Standardized reporting systems make cytopathology reports more meaningful and robust. It now became standard that these include by default elements, such as adequacy criteria, diagnostic groups, risk of malignancy (ROM), and recommendations for patient management. In this brief review, we attempted to summarize how these classification schemes emerged and how they are reshaping the landscape of diagnostic cytopathology.

Retrospective application of the Milan System for reporting salivary gland cytopathology: A Cancer Center experience

BACKGROUND

The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) was recently proposed. Herein, we retrospectively applied this nomenclature system to salivary gland lesions sampled by ultrasound-guided fine-needle aspiration (FNA).

METHODS

All cases of salivary gland FNA with available surgical follow-up, in the period from 2014 to 2017 at our institution were reviewed and reclassified according to one of the six categories of the MSRSGC, blind to the surgical outcome. Overall sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated, as well as risks of neoplasm (RON) and risk of malignancy (ROM) for each of the proposed categories.

RESULTS

There were 104 salivary gland lesions, with a female predominance (57.7%), most cases from the parotid gland (89.4%). Mean age was 53.2 years. Distribution of the specimens according to the Milan System was as follows: 19.2% nondiagnostic (ND), 8.7% non-neoplastic (NN), 9.6% atypia of undetermined significance (AUS), 40.4% benign neoplasm (BN), 14.4% salivary gland neoplasm of uncertain malignant potential (SUMP), 1.9% suspicious for malignancy (SFM), and 5.8% malignant. Sensitivity, specificity, PPV, and NPV using MSRSGC were calculated as 75%, 98.4%, 88.9%, and 95.3%, respectively. RON/ROM for each category were 60%/15% for ND, 44.4%/0% for NN, 90%/40% for AUS, 100%/9.5% for BN, 100%/13.3% for SUMP, 50%/50% for SFM and 100%/100% for malignant.

CONCLUSION

The use of the Milan System proved to be a useful method to predict the risk of neoplasm and malignancy in the sample studied, with high sensitivity and specificity.

Cytologic grading of primary malignant salivary gland tumors: A blinded review by an international panel

BACKGROUND

Fine needle aspiration (FNA) is commonly used for the preoperative evaluation of salivary gland tumors. Tumor grade is a key factor influencing clinical management of salivary gland carcinomas (SGCs). To assess the ability to grade nonbasaloid SGCs in FNA specimens, an international panel of cytopathologists convened to review and score SGC cases.

METHODS

The study cohort included 61 cases of primary SGC from the pathology archives of 3 tertiary medical centers. Cases from 2005 to 2016 were selected, scanned, and digitized. Nineteen cytopathologists blinded to the histologic diagnosis reviewed the digitized cytology slides and graded them as low, high, or indeterminate. The panelists' results were then compared to the tumor grades based on histopathologic examination of the corresponding resection specimens.

RESULTS

All but 2 of the 19 (89.5%) expert panelists review more than 20 salivary gland FNAs per year; 16 (84.2%) of the panelists work at academic medical centers, and 13 (68.4%) have more than 10 years' experience. Participants had an overall accuracy of 89.4% in the grading of SGC cases, with 90.2% and 88.3% for low- and high-grade SGC, respectively. Acinic cell carcinoma and mucoepidermoid carcinoma had the highest degree of accuracy, while epithelial-myoepithelial carcinoma and salivary duct carcinoma had the lowest degree of accuracy. As expected, the intermediate-grade SGC cases showed the greatest variability (high-grade, 42.1%; low-grade, 37.5%, indeterminate, 20.4%).

CONCLUSION

This study confirms the high accuracy of cytomorphologic grading of primary SGC by FNA as low- or high-grade. However, caution should be exercised when a grade cannot be confidently assigned.

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

BACKGROUND

Fine needle aspiration (FNA) is a routine sampling method in the diagnostic work up of salivary gland lesions. Despite universal use, no standardised classification existed for the cytopathological reporting of such entities until recently. The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) aims to standardise the reporting of these lesions, offering risk of malignancy rates and clinical management recommendations.

METHODS

We retrospectively applied MSRSGC to cases reported over a 5-year period. Salivary FNA specimens were reclassified according to the MSRSGC as (I) non-diagnostic, (II) non-neoplastic, (III) atypia of undetermined significance (AUS), (IV) benign neoplasm and salivary gland neoplasm of uncertain malignant potential, (V) suspicious for malignancy, and (VI) malignant. Cases with surgical resections were documented and risk of malignancy calculated for each group, where possible. We compared our outcomes with similar studies performed since publication of the Milan criteria.

RESULTS

In total, 192 specimens were reassigned as non-diagnostic (n = 30), non-neoplastic (n = 31), AUS (n = 1), benign neoplasm (n = 97) and salivary gland neoplasm of uncertain malignant potential (n = 4), suspicious for malignancy (n = 3), and malignant (n = 26). There were 73 surgical resections. Our calculated risk of malignancy was within the proposed MSRSGC rates for the non-diagnostic, benign neoplasm and malignant groups. One AUS case did not undergo surgery. Benign and malignant sensitivities and specificities for the original reporting categories were 88.24% and 95.72%, and 100% and 95.45% for the MSRSGC, respectively.

CONCLUSION

Salivary gland FNA has high diagnostic accuracy and the MSRSGC offers standardised reporting and assistance in the stratification of cases. This may improve communication between pathologists and clinicians with improved outcomes for patients.

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

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 fine-needle 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.

Implementation of the MILAN system for reporting salivary gland cytopathology: Interobserver concordance and cytohistological correlation of discordant cases

BACKGROUND

Fine needle aspiration cytology (FNAC) plays a pivotal role in evaluating salivary gland (SG) tumors. Several studies have shown diagnostic utility of MILAN system for reporting salivary gland cytopathology (MSRSGC) by examining risk of malignancy but only an occasional study has focused on interobserver variability. Hence, the present study was undertaken to assess the agreement among cytopathologists with varying experience in SG cytopathology using MSRSGC and to re-evaluate discordant cytohistological diagnoses for possible causes of misinterpretation.

METHODS

All SG lesions subjected to FNAC over a period of 3½ years were studied. The cases were critically reviewed by 2 pathologists with variable experience in cytopathology using MSRSGC and concordance level among them was calculated. Cytohistological discordant diagnoses were reclassified and possible causes of misinterpretation during routine reporting were evaluated.

RESULTS

Of 150 SG aspirates categorized according to MSRSGC, diagnostic disagreement between 2 pathologists was found in 10. Unweighted Cohen's Kappa score between consultant and resident was 0.812 (high). Among 55 cases with histological correlation, cytohistological discordance was seen in 12. True pitfalls constituted 50% of discordant cases while rest 50% were attributed to practical issues (turnaround time and heavy case load) during routine reporting.

CONCLUSION

MSRSGC can be used with good reproducibility between observers with variable cytopathology experience. Heterogeneous nature of SG neoplasm is a known pitfall in FNA diagnosis of SG neoplasms. During routine reporting turnaround time, heavy case load and reporting by cytopathologists with variable experience add on to challenges faced in reporting cytopathology of SG neoplasm.

The Role of Ancillary Techniques in Salivary Gland Cytopathology Specimens

Salivary gland tumor aspiration cytology is a useful preoperative test to guide the most appropriate clinical and surgical management for these patients. Although salivary gland cytology is often useful to distinguish between non-neoplastic lesions, benign neoplasms and malignant neoplasms, there remain many challenges in this area. Specifically, these tumors are uncommon and may have considerable morphologic overlap, especially in the setting of a malignant tumor. This article reviews some of the immunohistochemical and molecular characteristics of more common salivary gland neoplasms that pathologists and cytotechnologists may encounter. When used in combination with morphologic features, such ancillary testing can be useful to further refine the differential diagnosis, more strongly favor a particular entity, or in some instances confidently provide a specific diagnosis.

A Call for Universal Acceptance of the Milan System for Reporting Salivary Gland Cytopathology

OBJECTIVES

The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) established a standardized, tiered reporting system for salivary gland fine-needle aspiration (FNA) that has gained international acceptance among cytologists. Our goal was to review the key features of the MSRSGC to familiarize the surgical community with this system and its application to the FNA evaluation of salivary gland masses.

METHODS

A comprehensive review of the MSRSGC and its application in clinical practice.

RESULTS

The MSRSGC consists of six major diagnostic categories: 1) nondiagnostic, 2) non-neoplastic, 3) atypia of undetermined significance, 4) neoplasm (benign or salivary gland neoplasm of uncertain malignant potential), 5) suspicious for malignancy, and 6) malignant. Each diagnostic category is associated with an implied risk of malignancy with implications for clinical management.

CONCLUSIONS

The MSRSGC is similar to the system used for reporting thyroid FNA, which is familiar to most otolaryngologists and head and neck surgeons. As this reporting system continues to gain popularity among pathologists, widespread understanding by surgeons will be important to standardize communication and classification of salivary gland cytopathology to improve clinical care. Laryngoscope, 130:80-85, 2020.

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

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.

METHODS

All salivary gland FNAs performed from January 2009 to December 2016 were retrospectively categorised according to the MSRSGC. When available, pre-operative 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.

A critical appraisal of the Milan system for reporting salivary gland cytology (MSRSGC) with histological correlation over a 3-year period: Indian scenario

BACKGROUND

Fine needle aspiration cytology (FNAC) is the first line investigation for pre-operative diagnosis of salivary gland lesions, but due to its inherent limitations remains a challenge for the cytopathologists. The recently proposed international risk stratification scheme, the Milan System for Reporting Salivary Gland Cytology (MSRSGC) aims to promote and standardise the communication between cytopathologist and clinician thereby improving patient care.

METHODS

A retrospective study of all salivary gland cytology cases was performed over a 3-year period, reviewed by pathologists and categorised into 1 of the 6 diagnostic categories according to MSRSGC, namely, non-diagnostic, non-neoplastic, atypia of undetermined significance (AUS), benign neoplasm, and salivary gland neoplasm of undetermined significance (SUMP), suspicious for malignancy (SFM), and malignant neoplasm. Cyto- histological correlation was done wherever possible. Risk of malignancy (ROM) was calculated for each diagnostic category.

RESULTS

Out of a total of 150 salivary FNAC cases, histopathology was available for 64 cases. The sensitivity of FNAC was 81.8%, specificity was 100% while the diagnostic accuracy was 96.9%. The positive and negative predictive values were 100% and 96.4% respectively. The ROM for non-diagnostic, non-neoplastic, AUS, benign neoplasm, SUMP, SFM, and malignant categories were 0%, 10%, 50%, 2.5%, 50%, 100%, and 100% respectively.

CONCLUSION

MSRSGC fulfils the critical need for a uniform, internationally acceptable reporting system with ROM specified for each category. However, large scale multi centre studies need to be conducted before its reliability and validity is proven.

Impact on clinical follow-up of the Milan System for salivary gland cytology: A comparison with a traditional diagnostic classification

INTRODUCTION

No universally accepted classification exists for salivary gland FNA. The proposed Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) offers a uniform classification with management recommendations. We compared FNA diagnoses from a prior study with specific diagnoses with corresponding MSRSGC diagnoses.

METHODS

One-hundred and sixty-four cases from a prior cytological study with histological follow-up were re-reviewed by one of the authors and assigned to one of the MSRSGC categories. The original and MSRSCG diagnoses were compared, as were follow-up recommendations.

RESULTS

The MSRSGC system classified 29 specimens as non-diagnostic (seven histologically shown to be benign salivary gland, two non-mucinous cysts, 14 sialadenitis, one pleomorphic adenoma, one haemangioma, one lymphoma, one adenoid cystic carcinoma, one squamous carcinoma and one benign lymphoid proliferation). The original study diagnosed these lesions as: seven benign cysts, 15 benign salivary gland tissue, one benign neoplasm and two insufficient for diagnosis. In seven cases, MSRSGC disagreed with original diagnoses and surgical resection showed lesions where optimal follow-up was more consistent with original cytological diagnosis. In 10 cases with disagreement, the MSRSGC was associated with a more appropriate follow-up based on the surgical diagnosis. Malignancy risks for the Milan categories were: non-diagnostic (12%), non-neoplastic (5%), atypia of undetermined significance (19%), neoplasm, benign (5%), neoplasm (40%), suspicious for malignancy (60%) and malignant (93%).

CONCLUSION

MSRSGC was comparable with the original reported diagnoses in the majority of cases. Both systems had high accuracy for distinguishing benign from malignant lesions and both were associated with appropriate follow-up in most cases.

A retrospective 3-year study of salivary gland FNAC with categorisation using the Milan reporting system

INTRODUCTION

To assess our practice using the recently developed standardised classification system designated The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) and to ascertain the rates of malignancy for each category by means of a retrospective study.

METHODS

All salivary gland FNAC samples received between 1 January 2013 and 31 December 2015 were retrospectively assigned a diagnostic category code from the MSRSGC. Cytology results were correlated with subsequent histology (where available), and clinical and radiological follow up.

RESULTS

A total of 287 salivary gland FNA samples were received from 272 patients. The specimens were classified as non-diagnostic (21.3%), non-neoplastic (22%), atypia of undetermined significance (2.4%), neoplasm benign (36.9%), neoplasm of uncertain malignant potential (5.2%), suspicious for malignancy (1.7%) and malignant (10.5%; low grade 1.4% and high grade 9.1%). Histological and clinical/radiological follow up was available for 138 (48.1%) specimens, clinical/radiological follow up only for 145 (50.5%) and no follow up for the remaining four (1.4%) samples. The risk of malignancy for each category was non-diagnostic (8.5%), non-neoplastic (1.6%), atypia of undetermined significance (0%), neoplasm benign (1.9%), neoplasm of uncertain malignant potential (26.7%), suspicious for malignancy (100%) and malignant (100%).

CONCLUSIONS

The MSRSGC appears to be a useful tool to guide clinical management and provide an indication of possible risk of malignancy. We favour implementing use of these categories in our reporting practice with a future re-evaluation to assess maintenance of service quality as well as the clinical utility of this reporting system.

Fine Needle Aspiration Cytology for Neck Masses in Childhood. An Illustrative Approach

The primary indication of fine-needle aspiration cytology of the head and neck region is a thyroid nodule or a mass located in the cervical area or the head. Although a thyroid nodule may raise the suspicion of malignancy, less than one in 20 cases results in a carcinoma. In addition, the list of differential diagnoses is quite different according to the age of the patient. A number of benign lesions, such as branchial cysts, sialadenosis, and sialoadenitis are often seen in childhood and youth. The malignant lesions that are on the top of the list of a pediatric mass of the head and neck (H&N) region include rhabdomyosarcoma, neuroblastoma, and papillary carcinoma of the thyroid gland. This critical review of the diagnostic features of a pediatric mass of the H&N region is accompanied by panels of several cytology features that may be of help to the cytopathologist and clinician.