MUC4 is a valuable marker for distinguishing secretory carcinoma of the salivary glands from its mimics

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.

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.

Utility of MUC4 in the diagnosis of secretory carcinoma of salivary glands

Salivary gland tumors are diverse in morphology and both benign and malignant tumors may pose diagnostic challenges especially in small biopsies. Secretory carcinoma (SC) is histologically characterized by microcysts, follicles, solid growth pattern and occasional papillary structures, and absence of zymogen granules. SC is molecularly defined by the presence of novel gene fusion ETV6::NTRK3. Among the positive stains (S100 and mammaglobin), MUC4 is now another promising marker for the diagnosis of SC, that would enable the pathologists to exclude other morphologically close simulators. Aim of this study was to report clinicopathological features and assess utility of MUC4 in the diagnosis of SC. MUC4 was performed on 22 cases of SC. Glass slides were reviewed to record morphological patterns and staining of S100, mammaglobin, DOG1 and MUC4. Age ranged from 9 to 63 years with mean age of 34.41 ± 16.28 years. The male: female ratio was 72.7 %:27.3 %. The majority occurred in major salivary glands. A combination of patterns was seen; microfollicles were the most prevalent (90 %) followed by papillary-cystic and macrofollicles. MUC4 was positive in 19/21 (90 %) cases with almost equal number of 2+ and 3+ staining. MUC4 was negative in all cases of acinic cell carcinoma, polymorphous adenocarcinoma, adenoid cystic carcinoma, salivary duct carcinoma, myopepithelioma and myoeithelial carcinoma, cystadenoma and cribriform adenocarcinoma and all except 3 cases of mucoepidermoid carcinoma tested. Overall sensitivity of MUC4 was 95.4 %, specificity 90 %, p-value being <0.01, positive predictive value 87.5 % and negative predictive value 96.4 %. A characteristic cytoplasmic granular pattern was observed in 76.1 % tumors. S100 and mammaglobin were positive in all the performed cases. DOG1 was positive in 6/11 (28.5 %) tumors. In conclusion, MUC4 is a useful addition to a diagnostic immunohistochemical panel for SC, and to distinguish it from close potential mimickers such as acinic cell carcinoma, especially in practice settings where molecular testing is unavailable.

Cytopathology of benign sebaceous salivary gland neoplasia: Comparison of two analogous yet dissimilar entities

INTRODUCTION

Benign sebaceous salivary gland (SG) neoplasms represent approximately 0.2% of all salivary gland neoplasms. Not only are fine needle aspiration (FNA) biopsy findings of sebaceous adenoma (SA) and sebaceous lymphadenoma (SLA) limited, but their findings are also rarely compared with one another.

MATERIALS AND METHODS

Our cytopathology files were searched for examples of benign sebaceous SG neoplasms with concomitant histopathological verification. FNA biopsy and cell collection were performed using standard technique.

RESULTS

One case each of parotid SA and parotid SLA showed markedly dissimilar cytomorphology. The SA case was composed of a repetitive population of profusely multivacuolated polygonal cells with single and multiple nuclei, and was specifically recognised cytologically as a sebaceous neoplasm due to its characteristic cytoplasmic vacuolisation. The SLA case, however, was characterised by smears filled primarily with lymphocytes and only scant widely scattered basaloid cell clusters. A non-specific diagnosis of basaloid neoplasm was rendered. In retrospect, recognition of sebaceous differentiation was limited to rare cell groups.

CONCLUSION

Though nominally, epidemiologically, and to a degree histopathologically analogous, the cytopathology of SA and SLA are markedly dissimilar, reflecting the dominant cell component in each. With FNA biopsy, a specific interpretation is more likely for SA than SLA due to the overwhelming obscuring lymphoid population in the latter.

Defining the clinical characteristics of mammary analog secretory carcinoma of the salivary gland: Analysis of the National Cancer Database

Objectives

Mammary analog secretory carcinoma (MASC) is a classification of salivary gland tumors, recently included within the term secretory carcinoma. Previous descriptions of this diagnosis have largely consisted of case reports and case series with few studies investigating its clinical characteristics as compared to non-MASC tumors. Our objective was to use a large patient database to compare the clinical characteristics of mammary analog secretory carcinoma vs. non-mammary analog secretory carcinoma salivary gland tumors.

Methods

The National Cancer Database was queried between September and October 2022 for histological diagnosis of mammary analog secretory carcinoma and non-MASC salivary tumors. Patients diagnosed with mammary analog secretory carcinoma and non-mammary analog secretory carcinoma salivary tumors between the period of 2004 through 2019 were included in this analysis. Various demographic and clinical variables were abstracted from the database and compared using Wilcoxon rank sum and chi-square tests. Survival was compared between cohorts using Cox proportional hazards regression.

Results

Overall, compared to non-mammary analog secretory carcinoma diagnoses (n = 47668), mammary analog secretory carcinoma tumors (n = 384) affected younger individuals, displayed favorable pathologic staging and tumor grade, and were less likely to invade surrounding tissues. Patients with mammary analog secretory carcinoma tumors also received treatment more quickly following diagnosis compared to patients with non-mammary analog secretory carcinoma tumors. The risk of death was 4.3 times greater for non-mammary analog secretory carcinoma diagnoses when adjusted for patient variables (hazard ratio = 4.3, 95% confidence interval [2.37-7.71], p < 0.001).

Conclusions

Clinically, mammary analog secretory carcinoma salivary tumors have a more indolent course compared to other salivary cancers. Additional studies are needed to determine the natural history of this tumor type.

Salivary Gland-like Tumors of the Breast

CONTEXT

The World Health Organization classification of tumors of the breast recognizes several special type carcinomas and benign lesions with features comparable to those of salivary gland tumors.

OBJECTIVE

To discuss the histologic, immunophenotypic, molecular, and clinical features of salivary gland-like carcinomas of the breast. These breast tumors are often negative for hormone receptors and human epidermal growth factor receptor 2 (HER2), that is, triple-negative, but they generally have a much better prognosis than triple-negative breast carcinomas of no special type. We compare the immunophenotypic, molecular, and clinical features of these breast tumors with their salivary gland counterparts, highlighting similarities and differences. We also discuss benign salivary gland-like breast tumors. Finally, we highlight recent developments in understanding the molecular pathogenesis of these breast tumors and novel ancillary studies that can be used to support their diagnosis.

DATA SOURCES

A literature review was conducted, and papers were selected for further analysis and discussion by the authors of this review based on their novelty, applicability, and impact in the field.

CONCLUSIONS

Breast tumors that exhibit morphologic overlap with salivary gland tumors have been recognized by pathologists for decades, but the similarities and differences in their molecular pathogenesis have not been understood until more recently. These developments have led to novel diagnostic tools and further knowledge of these rare breast lesions.

Salivary Gland Secretory Carcinoma: Clinicopathologic and Genetic Characteristics of 215 Cases and Proposal for a Grading System

Salivary gland secretory carcinoma (SC), previously mammary analog SC, is a low-grade malignancy characterized by well-defined morphology and an immunohistochemical and genetic profile identical to SC of the breast. Translocation t(12;15)(p13;q25) resulting in the ETV6 :: NTRK3 gene fusion is a characteristic feature of SC along with S100 protein and mammaglobin immunopositivity. The spectrum of genetic alterations for SC continues to evolve. The aim of this retrospective study was to collect data of salivary gland SCs and to correlate their histologic, immunohistochemical, and molecular genetic data with clinical behavior and long-term follow-up. In this large retrospective study, we aimed to establish a histologic grading scheme and scoring system. A total of 215 cases of salivary gland SCs diagnosed between 1994 and 2021 were obtained from the tumor registries of the authors. Eighty cases were originally diagnosed as something other than SC, most frequently acinic cell carcinoma. Lymph node metastases were identified in 17.1% (20/117 cases with available data), with distant metastasis in 5.1% (6/117). Disease recurrence was seen in 15% (n=17/113 cases with available data). The molecular genetic profile showed ETV6 :: NTRK3 gene fusion in 95.4%, including 1 case with a dual fusion of ETV6 :: NTRK3 and MYB :: SMR3B . Less frequent fusion transcripts included ETV6 :: RET (n=12) and VIM :: RET (n=1). A 3-tiered grading scheme using 6 pathologic parameters (prevailing architecture, pleomorphism, tumor necrosis, perineural invasion (PNI), lymphovascular invasion (LVI), and mitotic count and/or Ki-67 labeling index) was applied. Grade 1 histology was observed in 44.7% (n=96), grade 2 in 41.9% (n=90), and grade 3 in 13.5% (n=29) of cases. Compared with low-grade and intermediate-grade SC, high-grade tumors were associated with a solid architecture, more prominent hyalinization, infiltrative tumor borders, nuclear pleomorphism, presence of PNI and/or LVI, and Ki-67 proliferative index >30%. High-grade transformation, a subset of grade 2 or 3 tumors, seen in 8.8% (n=19), was defined as an abrupt transformation of conventional SC into high-grade morphology, sheet-like growth, and a tumor lacking distinctive features of SC. Both overall survival and disease-free survival (5 and 10 y) were negatively affected by tumor grade, stage, and TNM status (each P <0.0001). SC is a low-grade malignancy with predominantly solid-microcystic growth patterns, driven by a gene fusion, most commonly ETV6 :: NTRK3 . There is a low risk for local recurrence and a good overall long-term survival, with a low risk for distant metastasis but a higher risk for locoregional lymph node metastasis. The presence of tumor necrosis, hyalinization, PNI and/or LVI, and positive resection margins correlate with higher tumor grade, less favorable prognosis, and increased mortality. The statistical results allowed us to design a 3-tiered grading system for salivary SC.

A Pediatric Case of High-Grade Secretory Carcinoma of the Maxillary Sinus With ETV6::NTRK3 Gene Fusion, Therapeutic Implications, and Review of the Literature

Secretory carcinoma (SC) is a salivary gland tumor with a generally low grade microscopic appearance, a characteristic immunophenotype, and a recurrent translocation leading to ETV6::NTRK3 fusion gene. Rare cases are reported in children. The maxillary sinus is an unusual localization. SC have an overall favorable prognosis, but cases with high grade morphology have been described in adult population and are related to a more aggressive clinical course. We present a pediatric case of secretory carcinoma involving the maxillary sinus with high grade morphology, with a review of the literature of secretory carcinomas with high grade component.

Secretory carcinoma of the salivary gland, a rare entity: An international multi-institutional study

BACKGROUND

Secretory carcinoma (SC) of the salivary gland is a rare entity with limited published literature on cytomorphology. The authors present the largest cohort to date of SC fine‐needle aspiration (FNA) cases.

METHODS

FNA cases of histologically confirmed SC were retrospectively retrieved from 12 academic institutions in the United States, Italy, Finland, and Brazil. The collated data included patient demographics, imaging findings, cytopathologic diagnoses according to the Milan System for Reporting Salivary Gland Cytopathology, cytomorphologic characteristics, and immunohistochemical/molecular profiles.

RESULTS

In total, 40 SCs were identified (male‐to‐female ratio, 14:26) in patients with a mean age of 52 years (age range, 13‐80 years). Ultrasound imagining revealed a hypoechoic, ovoid, poorly defined, or lobulated mass. The most common primary site was the parotid gland (30 of 40 tumors). Regional lymph node metastasis (9 patients) and distant metastasis (4 patients; brain, liver, lungs, and mediastinum) were noted. Two patients died of disease. FNA smears were cellular and demonstrated mainly large, round cells with intracytoplasmic vacuoles or granules and round‐to‐oval nuclei with smooth nuclear contour, minimal irregularities, and prominent nucleoli arranged predominantly in clusters, papillary formations, and single cells. The background was variable and contained inflammatory cells, mucin, or proteinaceous material. The diagnoses were malignant (19 of 38 tumors; 50%), suspicious for malignancy (10 of 38 tumors; 26%), salivary gland neoplasm of uncertain malignant potential (7 of 38 tumors; 18%), and atypia of undetermined significance (2 of 38 tumors; 6%) according to the Milan System for Reporting Salivary Gland Cytopathology. Two malignant cases (2 of 40 tumors; 5%) were metastases. The neoplastic cells were immunoreactive for S100 (23 of 24 tumors), mammaglobin (18 of 18 tumors), GATA‐3 (13 of 13 tumors), AE1/AE3 (7 of 7 tumors), and vimentin (6 of 6 tumors). ETV6‐NTRK3 fusion was detected in 32 of 33 tumors by fluorescence in situ hybridization (n = 32) and next‐generation sequencing (n = 1).

CONCLUSIONS

Familiarity with cytomorphologic features and the immunohistochemical/molecular profile of SC can enhance diagnostic accuracy.;

Secretory carcinoma of the salivary gland, which may manifest with diverse cytomorphology, mammaglobin expression, and ETV6 rearrangement or ETV6‐NTRK3 fusion, was investigated along with cytomorphologic features to facilitate an accurate diagnosis. The results indicated that familiarity with these features and with the immunohistochemical/molecular profile of secretory carcinoma of the salivary gland enhanced diagnostic accuracy.

Recent Advances on Immunohistochemistry and Molecular Biology for the Diagnosis of Adnexal Sweat Gland Tumors

Simple Summary

Cutaneous sweat gland tumors form an extremely diverse and heterogeneous group of neoplasms that show histological differentiation to the sweat apparatus. Due to their rarity, wide diagnostic range, and significant morphological overlap between entities, their accurate diagnosis remains challenging for pathologists. Until recently, little was known about the molecular pathogenesis of adnexal tumors. Recent findings have revealed a wide range of gene fusions and other oncogenic factors that can be used for diagnostic purposes and, for some, can be detected by immunohistochemistry. Among other organs containing exocrine glands, such as salivary glands, breasts, and bronchi, most of these biomarkers have been reported in homologous neoplasms that share morphological features with their cutaneous counterparts. This review aims to describe these recent molecular and immunohistochemical biomarkers in the field of sweat gland tumors.

Abstract

Cutaneous sweat gland tumors are a subset of adnexal neoplasms that derive or differentiate into the sweat apparatus. Their great diversity, rarity, and complex terminology make their pathological diagnosis challenging. Recent findings have revealed a wide spectrum of oncogenic drivers, several of which are of diagnostic interest for pathologists. Most of these molecular alterations are represented by gene fusions, which are shared with other homologous neoplasms occurring in organs containing exocrine glands, such as salivary and breast glands, which show similarities to the sweat apparatus. This review aims to provide a synthesis of the most recent immunohistochemical and molecular markers used for the diagnosis of sweat gland tumors and to highlight their relationship with similar tumors in other organs. It will cover adenoid cystic carcinoma (NFIB, MYB, and MYBL1 fusion), cutaneous mixed tumor (PLAG1 fusion), cylindroma and spiradenoma and their carcinomas thereof (NF-κB activation through CYLD inactivation or ALKP1 hotspot mutation), hidradenoma and hidradenocarcinoma (MAML2 fusion), myoepithelioma (EWSR1 and FUS fusion), poroma and porocarcinoma (YAP1, MAML2, and NUTM1 fusion), secretory carcinoma (ETV6, NTRK3 fusion), tubular adenoma and syringo-cystadenoma papilliferum (HRAS and BRAF activating mutations). Sweat gland tumors for which there are no known molecular abnormalities will also be briefly discussed, as well as potential future developments.

[Salivary gland tumors-an overview : Advances in molecular characterization: Part I]

In den letzten Jahren hat die Charakterisierung der Speicheldrüsenkarzinome einen großen Wandel durchlebt. Morphologisch definierte Entitäten konnten zu einem Großteil auch molekular mit einem oftmals distinkten Genotyp charakterisiert werden. Der erste Teil des Artikels gibt einen Überblick über die Fortschritte der molekularen Charakteristiken des Mukoepidermoidkarzinoms, adenoid-zystischen Karzinoms, Azinuszellkarzinoms, des sekretorischen und intraduktalen Karzinoms sowie des hyalinisierenden klarzelligen Karzinoms. Der molekulare Genotyp kann dabei insbesondere bei der Klassifizierung ungewöhnlicher morphologischer Varianten von großem Nutzen sein. Rekurrente NTRK- oder RET-Genfusionen können dabei nicht nur als diagnostisches Hilfsmittel, sondern auch für eine potenzielle gezielte Therapie genutzt werden.

Head and Neck Low-Grade Fibromyxoid Sarcoma: A Clinicopathologic Study of 15 Cases

Low-grade fibromyxoid sarcoma (LGFMS) is an uncommon mesenchymal tumor usually arising in the lower extremities and trunk. Only rare examples in the head and neck region have been reported. Fifteen cases of head and neck LGFMS were retrieved. MUC4 was performed on all cases. Results for smooth muscle actins, β-catenin, desmin, S100 protein, Epithelial membrane antigen (EMA) and STAT6 immunohistochemistry, as well as FUS rearrangement status, were recorded when available. Sites included neck (8), supraclavicular region (4) and orbit (1), parapharyngeal space (1) and lower lip (1). The age of the patients ranged from 3 to 97 years (median, 26 years). Tumors displayed classical morphologic features of LGFMS, as described. All cases (15/15) were positive for MUC4, and all cases tested (4/4) harbored FUS rearrangement. Variable positivity for EMA was identified in one case. Follow-up was available in 11 patients, ranging from 2 to 240 months (mean 71.4 months; median, 44 months). Three tumors recurred locally; none metastasized. In conclusion, although distinctly uncommon, LGFMS may arise in the head and neck region and should be distinguished from other more common spindle cell tumors in these locations. The morphologic, immunohistochemical and molecular genetic features of head/neck LGFMS are identical to those occurring elsewhere. The long-term metastatic risk of LGFMS in these locations remains to be fully elucidated.

High-grade Transformation/Dedifferentiation in Salivary Gland Carcinomas: Occurrence Across Subtypes and Clinical Significance

High-grade transformation (HGT) or dedifferentiation has been described in a variety of salivary gland carcinomas, including acinic cell carcinoma, secretory carcinoma, adenoid cystic carcinoma, epithelial-myoepithelial carcinoma, polymorphous adenocarcinoma, low-grade mucoepidermoid carcinoma, and hyalinizing clear cell carcinoma. High-grade (HG) transformed tumors are composed of a conventional low-grade component characterized by specific microscopic and immunohistochemical features for the given entity, intermingled with or juxtaposed to areas of HG morphology. This is usually either poorly differentiated adenocarcinoma, carcinoma not otherwise specified, or undifferentiated carcinoma, in which the original line of differentiation is lost. The HG component is composed of solid nests of anaplastic cells with large vesicular pleomorphic nuclei, prominent nucleoli, and abundant cytoplasm. Frequent mitoses and extensive necrosis may be present. The Ki-67 labeling index is consistently higher in the HG component. The molecular genetic mechanisms responsible for HGT of salivary gland carcinomas are largely unknown, though p53 inactivation and human epidermal growth factor receptor 2 overexpression and/or gene amplification have been demonstrated in the HG component in a few examples, the frequency varies for each histologic type. Salivary gland carcinomas with HGT are more aggressive than conventional carcinomas, with a higher local recurrence rate and a poorer prognosis. They have a high propensity for cervical lymph node metastasis suggesting a need for a wider resection and neck dissection. HGT of salivary gland carcinoma can occur either at initial presentation or less commonly at the time of recurrence, sometimes following postoperative radiotherapy. The potential for HGT in almost any type of salivary gland carcinoma warrants a thorough sampling of all salivary gland malignancies to prevent oversight of a HG component.