Morphology in conjunction with immunohistochemistry is sufficient for the diagnosis of mammary analogue secretory carcinoma

Salivary Gland Secretory Carcinoma; Review of 13 Years World-Wide Experience and Meta-Analysis

OBJECTIVES

Secretory Carcinoma is a malignant salivary gland tumor, initially described in 2010. This rare tumor is associated with the translocation t(12;15) (p13;q25), resulting in the fusion gene ETV6-NTRK3. Since this tumor is quite rare, most publications describe only small cohorts of patients. We aimed to investigate the clinical, pathological, and prognostic features of this newly defined malignant entity.

DATA SOURCES

Pubmed, Google Scholar, and Web of Science databases.

REVIEW METHODS

All published articles between 2010 and 2023 were reviewed. Search terms included the terms "Mammary Analogue Secretory Carcinoma" and "Secretory Carcinoma". All articles published in English reporting on Secretory Carcinoma of salivary glands were retrieved.

RESULTS

One-hundred and 12 retrospective articles reporting a total of 674 patients were included, with 52% males and a mean age of 44.9 ± 18.9. The event rate for patients with advanced-stage disease (Stage 3/4) at presentation was 24.1% (95% CI 17.6%-31.9%, I2  = 9.2%), 14.6% for regional metastases (95% CI 10.5%-20%, I2  = 12%), and the event rate of distant metastasis was 8.4% (95% CI 5.5%-12.7%, I2  = 4.2%). Adjuvant radiotherapy was administered for 30.3% of patients (95% CI 24.1%-37.2%, I2  = 21.5%). The recurrence rate was 19% (95% CI 15.1%-23.8%, I2  = 5%). Survival outcomes showed a 17.2% death of disease rate for Secretory Carcinoma patients (95% CI 13.5%-21.8%, I2  = 7.3%).

CONCLUSIONS

Secretory Carcinoma is a rare and relatively newly defined entity arising in the parotid gland most commonly. Characterized as a low-grade tumor, the majority of patients are diagnosed at an early stage, without regional or distant disease, and the prognosis is relatively good.

LEVEL OF EVIDENCE

NA Laryngoscope, 134:1716-1724, 2024.

Salivary gland secretory carcinoma presenting as a cervical soft tissue mass: a case report

BACKGROUND

Secretory carcinoma (SC) has been described as a distinct salivary gland tumor in the fourth edition of the World Health Organization (WHO) classification of head and neck tumors. SC is generally considered as a slow-growing low-grade malignant tumor, while several cases have been reported with high-grade features, and even metastases in the literature up until now. In this article, a soft tissue SC case is discussed with high-grade microscopic features and neural invasion. A review of the salivary gland SC cases with aggressive behavior is also debated.

CASE PRESENTATION

A 65-year-old Caucasian man presented with a left neck mass for the past six months. The imaging studies demonstrated a very large cystic cervical mass (46 × 23 mm) with papillary projections in the anterolateral aspect of the left neck zone Vb. He underwent left radical neck dissection (level I-V) and was followed up for 12 months with the diagnosis of Secretory carcinoma.

CONCLUSION

Although SC generally has a good outcome, multiple recurrences and unusual metastases may occur, which should be considered by either the pathologists or clinicians.

The genetic and immune features of salivary gland secretory carcinoma with high-grade transformation

OBJECTIVES

To compare the clinicopathological, molecular, and immune features of conventional and high-grade transformation (HGT) secretory carcinoma (SC) in salivary glands.

MATERIALS AND METHODS

The clinicopathological data of 88 cases including 74 conventional SCs and 14 SCs with HGT were reviewed. Targeted next-generation sequencing was performed in 11 SCs with HGT and 7 conventional SCs. The level of PD-L1 and CD8+ TILs was determined by immunohistochemistry.

RESULTS

Compared with the conventional group, the rates of nodal metastasis, local recurrence, distant metastasis and mortality were significantly higher in the HGT cohort. Mutations of ARID1A/B, KMT2A, HOXD13, NRG1 and ETV6 genes were identified in HGT SCs. A recurrent E307G mutation in GATA6 gene was also observed in two cases. Two deceased HGT patients with distant metastasis harboured NOTCH3 mutations. ETV6-RET translocation was prone to occur in the HGT SCs. Additionally, PD-L1 expression was low, and CD8+ TILs were sparse in most HGT cases.

CONCLUSION

Our findings reveal novel gene alterations involved in the progression of HGT in SCs. Most HGT SCs patients cannot benefit from PD-L1 blocking and may be approached with a distinct treatment strategy including the lymph node dissection and application of molecular target drugs in precision oncology.

Efficacy of Fine-Needle Aspiration Cytology in Diagnosing Secretory Carcinoma of Salivary Gland: A Systematic Review and Meta-Analysis

INTRODUCTION

The diagnosis of salivary gland secretory carcinoma (SC) in fine-needle aspiration specimens is challenging because its low-grade nature makes it difficult to differentiate it from various benign or malignant salivary gland neoplasms. Currently, the gold standard is demonstration of ETV6-NTRK3 fusion gene. However, the decision for ordering this costly molecular testing can be facilitated by the correct recognition of its cytomorphological features. The aim of the review was to determine the accuracy of fine-needle aspiration cytology (FNAC) in diagnosis of salivary gland SC. The secondary objective was to recognize varied cytomorphological patterns, characteristic features of SC and differentiate it from other neoplasms.

METHODS

PubMed/MEDLINE, Science Direct, Embase, Cochrane review, and PROSPERO databases were searched for studies having the following key search terms: ("secretory carcinoma of salivary gland" OR "mammary analogue secretory carcinoma of salivary gland") AND ("Cytology" OR "Cytological features" OR "aspirate" OR "cytodiagnosis") published in the time frame of 2010 to June 2023. Studies reporting cytological features of the salivary gland tumors which were confirmed/diagnosed as SC on molecular investigation, were included in the systematic review. Finally, seventeen studies reporting a total of 45 cases were included in the metanalysis.

RESULTS

The sensitivity of the FNAC in diagnosing SC in salivary gland is 27.7% (95% CI: 16.6-42.5%). The LR+ (positive likelihood ratio) was 0.654 (0.344-1.245), LR- (negative likelihood ratio) was 1.023 (0.538-1.946), and diagnostic odds ratio was 0.421 (0.129-1.374). The molecular testing and/or immunohistochemistry performed on cell block increased the diagnostic accuracy.

CONCLUSION

Recognition of subtle cytomorphological patterns, i.e., papillary formation, clusters, and singly dispersed cells along with presence of fine intracytoplasmic vacuolations were the characteristic findings in majority of cases, confirmed with diagnostic molecular profiling. This may be helpful in identification of this rare entity with limited published literature and help in increasing diagnostic accuracy.

MASC Gets UNMASKED: Visiting a Rare Tumor with Emphasis on Cytomorphological Features

Background

Secretory carcinoma (SC) is a newly described entity which has been often misdiagnosed earlier as acinic cell carcinoma on cytology. Diagnosing SC was initially based upon identifying the ETV6:NTRK3 fusion gene with the help of fluorescence in situ hybridization (FISH). Lately, with more knowledge of the reliable histomorphology, cytology, and immunohistochemistry features, definitive diagnosis can be confidently made without the help of FISH in almost every case.

Materials and Methods

Six histologically confirmed cases of SC were studied. The cytology slides of all the six cases were retrieved and reviewed to identify the characteristic features which could have helped in raising the possibility of SC on fine needle aspiration cytology itself. Cell blocks were also studied, wherever available.

Results

Patients were all male with average age of 35.2 years. The six cases in the current study demonstrated at least focal cytoplasmic vacuolization of varying sizes, papillae formations, and bland nuclear features on fine needle aspirate smears. It was also seen that S-100 and mammaglobin immunohistochemistry (IHC) are very helpful in confirming the diagnosis.

Conclusions

The results of the current study highlight the cytomorphological features which may help in clinching the diagnosis SC on cytology itself. They also highlight certain cytological features which help to rule out the other differential diagnoses.

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.

Secretory Carcinoma of Salivary Glands: A Case Series and Review of Literature

Mammary analogue of secretory carcinoma is a recently described entity in WHO 2017 classification of head and neck tumours. It resembles secretory carcinoma of breast. It usually affects the salivary glands and has an indolent behaviour. We reviewed five cases of Mammary analogue of secretory carcinoma in our institute and compared our results with existing literature. All the patients underwent surgical resections and appropriate adjuvant treatment. Immunohistochemistry is an alternative cost effective tool as compared to genetic testing to differentiate secretory carcinoma from its mimickers. Surgery with adequate margins followed by adjuvant therapy is the treatment of choice.

Secretory carcinoma of major and minor salivary glands with ETV6-NTRK3 gene fusion: overcoming misdiagnosis in the era of tumour-agnostic therapy with TRK inhibitors

Introduction

Secretory carcinoma (SC) of the salivary gland is an extraordinarily rare tumour. Accurate diagnosis of SC is crucial for understanding the clinical course, prognosis, and selection of optimal therapy. The aim of this research was to analyse retrospectively the clinical and pathological characteristics of patients diagnosed with SC of the salivary gland from 2017 onwards, which aligns with its addition to the World Health Organization classification.

Material and methods

We conducted a retrospective, single-centre, clinicopathological analysis of patients diagnosed with SC of the salivary gland between 2017 and 2022. The analysis included the evaluation of NTRK3 gene rearrangements and immunohistochemical (IHC) profiling.

Results

The study included 6 patients, comprising 4 women and 2 men. The average age of the patients was 50 years (standard deviation 26). Three cases presented with tumours in the parotid gland, while one case each involved the submandibular gland, sinonasal tract, and buccal mucosa. Interestingly, despite the characteristic IHC profile, each case was initially diagnosed as a different type of salivary gland cancer. Next-generation sequencing analysis was performed in 3 cases, revealing the presence of the ETV6-NTRK3 fusion gene. This cohort notably features an intriguing case: the youngest patient documented in literature, distinguished by extended follow-up and delayed recurrence.

Conclusions

In summary, emphasizing the risk of misdiagnosis is pivotal in the context of SC of the salivary gland, which can manifest across diverse glandular sites. Accurate diagnosis, underscored by the assessment of NTRK3 gene rearrangements, assumes a critical role in guiding effective management and treatment decisions.

Secretory Carcinoma of the Salivary Gland: A Rarity in Children

Originally described as mammary analog secretory carcinoma (SC), SC of the salivary gland is a rare malignancy with morphologic and molecular similarities to SC of the breast. We present 2 children with salivary gland SC with the classic ETV6-NTRK3 gene fusion, including 1 with lymph node metastases. Both patients underwent surgical resection and were in remission 24 months postsurgery. One patient was additionally found to have synchronous papillary thyroid carcinoma with a TFG-MET fusion. A review of published cases highlights the expanding molecular profile and confirms the favorable course of salivary gland SC after surgical resection.

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.

Clinicopathological investigation of secretory carcinoma cases including a successful treatment outcome using entrectinib for high-grade transformation: a case report

Background

Secretory carcinoma (SC) of the salivary gland is a recently described malignant tumor harboring characteristic ETV6-NTRK3 gene fusion. SC generally has a favorable clinical course, and is currently regarded as a low-grade carcinoma. However, a small subset of SCs demonstrates aggressive clinical features with histologically high-grade transformed morphology, the molecular pathogenesis of which has not yet been elucidated. In this study, we performed a clinicopathological and molecular genetic study of patients with SC of the head and neck displaying various clinical characteristics to investigate the differences of pathological and molecular genetics between low-grade and high-grade components of SC.

Case presentation

Three cases with SC of the head and neck, including a conventional low-grade SC and two high-grade transformed SCs are described. High-grade transformed SCs with histological features such as nuclear polymorphism, distinctive nucleoli and increased mitotic activity developed locoregional recurrence and distant metastasis. Immunohistochemical analysis revealed that low- and high-grade components showed different expression patterns for S-100 protein and mammaglobin, whereas all examined components were positive for p-STAT5. p53-positive cell population was markedly higher in one case with high-grade transformed SC. The proliferative activity of high-grade components was markedly increased, with the Ki-67 labeling index ranging up to 30–32%. A fluorescence in situ hybridization study with an ETV6 (12p13) break apart probe revealed split signals in the nuclei in all 3 cases. A targeted next-generation sequencing-based fusion assay demonstrated that all 6 clinical samples from the 3 patients showed the presence of the ETV6-NTRK3 fusion transcripts. One patient with high-grade transformed SC showed a dramatic clinical response to the pan-TRK inhibitor, entrectinib, for the treatment of locoregional recurrence and pulmonary metastasis.

Conclusions

High-grade transformed SC showed aggressive clinical and pathological features with increased Ki-67 labeling index. Molecular genetic study of gene rearrangement appears to be beneficial treatment as the presence of ETV6-NTRK3 translocation may represent a therapeutic target in SC, particularly the high-grade transformed type.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01155-6.

Prognostic factors in mammary analogue secretory carcinomas of the parotid gland: Systematic review and meta-analysis

Mammary analogue secretory carcinomas (MASCs) of the parotid gland are considered as low-grade malignancies with good clinical outcome but lacking data regarding prognostic factors. We performed meta-analysis assessing prognostic factors for disease-free survival (DFS) and overall survival (OS) in 256 patients with MASCs of the parotid gland. A total of 73 studies have met the inclusion criteria and 76.3% of patients were seen with T1 and T2 tumors and negative neck nodes. Lymph node metastasis (57.4%) and distant recurrences (46.2%) were particularly found in T4 tumors (p < 0.001). DFS at 5 and 10 years was 77.9% and 47.2% compared to 88.1% and 77.2% for OS at the same time points. Male sex, T3-T4 tumors, and recurrent disease represented independent worse prognosticators for survival outcome. Altogether, parotid gland MASCs show good long-term outcome, but T4 tumors behave significantly more aggressive and require extended treatment strategies along with close follow-ups.

Diagnosis and treatment of secretory carcinoma arising from the oral minor salivary gland: Two case reports

INTRODUCTION

Secretory carcinoma (SC) is a malignancy of the salivary glands, which is similar to SC of the breast regarding its association with neurotrophic tyrosine receptor kinase fusion-positive gene. SC is a recently described salivary gland tumor, and there are a few reports describing oral minor salivary gland-derived SC. We reported two cases of SC in the oral cavity and reviewed the literature.

PATIENT CONCERNS

The patients included a 65-year-old Japanese woman who presented with a mass of the upper lip and an 84-year-old Japanese man who presented with a mass on the buccal mucosa.

DIAGNOSIS

Diagnosis was based on histomorphological and immunohistochemical findings and identification of a specific translocation of the ETS variant 6-neurotrophic receptor tyrosine kinase 3 gene fusion. Case 1 was finally diagnosed using reverse transcription-polymerase chain reaction with formalin-fixed paraffin-embedded tissue samples, while case 2 was diagnosed using fluorescence in situ hybridization analysis.

INTERVENTIONS AND OUTCOMES

In case 1, excisional biopsy was done and there was no recurrence observed in five-year follow-up. In case 2, tumor resection was done and there was no recurrence observed in two-year follow-up.

CONCLUSION

It is highly likely for many cases of SC to be initially diagnosed as acinic cell carcinoma (AciCC) owing to their similar histological findings. The treatment strategy for minor salivary gland-originated SC is similar to that of AciCC; however, SC is often highly malignant and involves a high risk of cervical lymph node metastasis. Thus, establishing an accurate diagnosis together with pathologists and confirming the presence of the ETS variant 6-neurotrophic receptor tyrosine kinase 3 fusion gene using genetic analysis is important.

Mammary analogue secretory carcinoma of a salivary gland of the hard palate with contralateral cervical lymph node metastases: A case report

Mammary analogue secretory carcinoma (MASC) is a rare malignant tumour of the salivary glands, with only few cases reported in the literature to date. Initial preoperative staging is crucial for all patients with an oral malignancy to visualize the tumour, detect lymph node or distant metastases and plan therapeutic interventions. In the case presented herein, radiological imaging revealed a tumour of the right hard palate with suspected positive contralateral lymph nodes. Therefore, local tumour resection comprising hemimaxillectomy and bilateral neck dissection was performed. The diagnosis of MASC was finally based on characteristic histopathological and immunohistochemical findings, such as S100 protein and mammaglobin positivity. The diagnosis of MASC may be challenging, as such findings lack specificity. To confirm the diagnosis, molecular genetic examinations may be performed to detect a highly specific ETV6-NTRK3 fusion gene. Depending on the results of these examinations, surgery, alone or combined with adjuvant radiation or chemoradiation, is the recommended approach. In summary, MASC should be treated similarly to other low-grade salivary gland tumours, such as acinic cell carcinoma, as they exhibit biological and histopathological similarities.

A systematic review of secretory carcinoma of the salivary gland: where are we?

OBJECTIVE

The aim of this systematic review was to describe the epidemiology, diagnostic criteria, differential diagnosis, treatment, prognostic factors, and treatment outcomes of secretory carcinoma.

STUDY DESIGN

A comprehensive search of Lilacs, PubMed, Science Direct, and Web of Science databases was conducted to identify all case reports, letter to the editor, and histopathologic reclassifications regarding salivary gland secretory carcinoma published in English, Spanish, French, and Portuguese.

RESULTS

The final analysis included 119 studies, which totaled 642 secretory carcinoma diagnoses, with 239 case reports and 403 diagnostic reclassifications, mostly in the United States. The age range was 5 to 87 years, and cases were predominantly in males (58.7%) and mostly affecting the parotid glands (73.7%). The disease usually presents as a slow-growing, painless mass. The main differential diagnosis is acinic cell carcinoma, and the tumor is usually treated with surgery. The prognosis is considered favorable, although there have been reports of local recurrences, distant metastases, and deaths.

CONCLUSIONS

It is important that clinicians become aware of this salivary gland neoplasm and report clinical data, clinical course, management and long-term follow-up. There is an urgent need to conduct more clinical trials, especially on tropomyosin receptor kinase (TRK) inhibitors and other potential target therapy modalities.

Mammaglobin protein localization and gene expression in the salivary glands

PURPOSE

This study aims to delve deeper into the hypothesis that normal salivary gland tissue expresses both protein and mRNA of mammaglobin (MGB).

METHODS

Formalin-fixed paraffin-embedded samples of submandibular (10), parotid (5), palatal (5) and labial glands (30) salivary glands were immunohistochemically investigated. The labial samples were used to examine the MGB positive ratio (MGB-PR), and localize MGB by double immunofluorescence staining and quantitative mRNA gene expression. Mann-Whitney U and Kruskal Wallis rank-sum test for group comparison, and Spearman's rank correlation coefficient for correlation analysis were used.

RESULTS

The distribution of MGB-positive cells was variable throughout samples with significantly higher MGB-PR of acini than ducts (P = 0.00376), and there was no difference when compared based on age (P = 0.0646) and gender (P = 0.245). Besides acinar cells, a number of myoepithelial cells and ductal cells also demonstrated strong MGB reactivity with varying MGB mRNA expression levels in 6 of the 7 samples (with MGB-PR > 20%) tested.

CONCLUSION

This novel study shows that unlike aberrant protein expression in some carcinomas, MGB expression in salivary gland neoplasms represents the nature of original cells, giving a better insight into the neoplasms expressing MGB.

Clinicopathologic and Molecular Characterization of Four Cases of Pediatric Salivary Secretory Carcinoma (SSC), One with ETV6-RET Fusion

Salivary gland secretory carcinoma (SSC) is a neoplasm with characteristic histologic features, similar to those of secretory carcinoma of the breast. Only a few pediatric SSC cases have been reported, all with ETV6-NTRK3 fusion. We present four new pediatric SSC examples, one with a novel ETV6-RET fusion. Four cases of SSC were diagnosed between 2010 and 2020: 2 boys, 7 and 9 year-old with parotid tumors (1.5 and 1.3 cm, respectively); and two 14 year-old girls: one with a submandibular tumor (2.1 cm), and one with a parotid lesion (1.2 cm). Histologically, all tumors were similar: well-circumscribed lesions composed by mid-size, monotonous cells with eosinophilic and sometimes vacuolated cytoplasm. The nuclei are oval to round with open chromatin and a single nucleolus. There are duct-like structures and microcysts with colloid-like material. Immunohistochemically, tumor cells are positive for S100, CK7, mammaglobin and GATA3. A classic ETV6-NTRK3 translocation was confirmed in the three parotid tumors; an ETV6-RET fusion was demonstrated in the submandibular lesion. All patients underwent complete surgical resection and are alive without tumor recurrence after a follow-up time ranging from one to 4 years. Pediatric SSC is extremely rare but their characteristic morphology and immunohphenotype facilitate their diagnosis. We describe the first pediatric case with the recently reported ETV6-RET fusion. Similar to adult cases, this tumor is morphologically undistinguishable from those carrying the classic ETV6-NTRK3 translocation. Thus, in pediatric cases with morphology suggestive of SSC and negative ETV6-NTRK3 by RT-PCR, other possible fusions should be investigated.

A case of "ETV6-FISH-negative" secretory carcinoma of the parotid gland: immunohistochemical study

Secretory carcinoma of the salivary glands is a relatively new disease concept, and is characterized by "morphological resemblance to mammary secretory carcinoma and ETV6-NTRK3 gene fusion." Herein we describe a confusing case and briefly discuss practical diagnostic problems. The patient was a 71-year-old Japanese man who had a tumor consistent with secretory carcinoma at the microscopic and immunohistochemical levels. Immunohistochemically, EMA and S100 protein were noted to be positive along with various cytokeratins as well as mammaglobin and pSTAT5. Moreover, vimentin was focally positive. Smooth muscle actin, p63, p40, and androgen receptor were negative. However, a search using fluorescence in situ hybridization did not reveal a definite split signal for the ETV6 gene. It is presumed that confirming the diagnosis of secretory carcinoma without genetic retrieval will be accepted as a diagnostic method, and we hope that worldwide general recognition may earlier reach "gradual acceptance."

Intraductal carcinoma of the salivary gland with NCOA4-RET: expanding the morphologic spectrum and an algorithmic diagnostic approach

After the publication of the 2017 World Health Organization Classification of Head and Neck Tumours, there has been increasing interest in the classification of newly categorized intraductal carcinomas. Intraductal carcinoma (IC) is an indolent tumor, typically arising in the parotid gland, with an intact myoepithelial layer and a cystic, papillary, often cribriform architecture. Early studies of IC identified a heterogeneous group of molecular alterations driving neoplasia, and recent studies have defined three primary morphological/immunohistochemical variants, subsequently linking these morphologic variants with defined molecular signatures. Although studies to date have pointed toward distinct molecular alterations after histological classification, this study used a novel approach, focusing primarily on six cases of IC with NCOA4-RET gene rearrangement as determined by next-generation sequencing and describing the spectrum of clinicopathologic findings within that molecularly-defined group, among them a unique association between the NCOA4-RET fusion and hybrid variant IC and the first case of IC arising in association with a pleomorphic adenoma. RET-rearranged IC show histological and immunohistochemical overlap with the more widely recognized secretory carcinoma, including low-grade morphology, a lumen-forming or microcystic growth pattern, and co-expression of S100, SOX10, and mammaglobin, findings undoubtedly leading to misdiagnosis. Typically regarded to have ETV6-NTRK3 fusions, secretory carcinomas may alternatively arise with RET fusions as well. Adding our cohort of six NCOA4-RET fusion-positive IC compared with four cases of secretory carcinoma with ETV6-RET fusions and a single case of fusion-negative IC with salivary duct carcinoma-like genetics, we propose a diagnostic algorithm that integrates histological elements, including atypia and invasiveness, and the likelihood of specific molecular alterations to increase diagnostic accuracy in what can be a very subtle diagnosis with important clinical implications.

Immunocytochemistry for diagnostic cytopathology-A practical guide

Cytological specimens, which are obtained by minimally invasive methods, are an excellent source of diagnostic material. Sometimes they are the only material available for diagnosis as well as for prognostic/predictive markers. When cytomorphology is not straightforward, ancillary tests may be required for a definitive diagnosis to guide clinical management. Immunocytochemistry (ICC) is the most common and practical ancillary tool used to reach a diagnosis when cytomorphology is equivocal, to differentiate entities with overlapping morphological features, and to determine the cell lineage and the site of origin of a metastatic neoplasm. Numerous immunomarkers are available, and some are expressed in multiple neoplasms. To rule out entities within a differential diagnosis, the use of more than one marker, sometimes panels, is necessary. ICC panels for diagnostic purposes should be customised based on the clinical context and cytomorphology, and the markers should be used judiciously to preserve material for additional tests for targeted therapies in the appropriate setting. This review offers a practical guide for the use of ICC for diagnostic cytopathology, covering the most commonly encountered non-hematolymphoid diagnostic scenarios in various body sites.

High-grade salivary gland carcinoma with the ETV6-NTRK3 gene fusion: A case report and literature review of secretory carcinoma with high-grade transformation

Secretory carcinoma or mammary analog secretory carcinoma is an entity of salivary gland carcinoma that is characterized by the ETV6-NTRK3 gene fusion. Although it is generally considered to be a low-grade malignancy, some cases of secretory carcinoma with high-grade transformation (SCHG) have been reported. We herein describe a case of SCHG composed almost exclusively of the high-grade component. The patient presented with a growing mass in the buccal mucosa and underwent surgery. Tumor cells showing high-grade nuclear atypia were arranged in solid or cribriform nests with comedo-like necrosis. A differential diagnosis included high-grade salivary gland carcinoma, such as salivary duct carcinoma. Immunohistochemically, tumor cells were focally positive for S-100 and negative for mammaglobin and showed nuclear positivity for pan-Trk. A reverse transcription polymerase chain reaction assay showed that the tumor harbored the ETV6-NTRK3 gene fusion. A histological review of microscopic slides of the tumor did not reveal a typical secretory carcinoma component, except for a very focal area. We ultimately diagnosed this tumor as SCHG. This case underscores the importance of recognizing the histological spectrum of SCHG and the utility of pan-Trk immunohistochemistry to detect secretory carcinoma, which may be targeted by tyrosine kinase inhibitors.

Secretory Carcinoma of the Oral Cavity: A Retrospective Case Series with Review of Literature

Secretory carcinoma (SC) is an uncommon salivary gland neoplasm of the oral cavity that microscopically may mimic acinic cell carcinoma (ACC) and mucoepidermoid carcinoma (MEC). This study describes a series of SC in minor glands with a literature review. We performed a retrospective search for oral SC, within the archives of the University of Florida, Oral Pathology and Surgical Pathology Biopsy services from 2010 to 2018. A total of 10 SCs were identified in the oral and maxillofacial region, four of which were in the minor salivary glands. The demographic, clinical, histological, and molecular findings were aggregated for all 4 cases. Patient age varied from 30 to 60 years, with an average of 45 years. Two cases each were in female and male patients. Two cases presented on the labial mucosa, and one each on the hard and soft palate. Immunohistochemical (IHC) staining showed mammaglobin positivity in all cases, GATA3 positivity in two cases, S100 positivity in three cases, and SOX10 positivity in only one case. Fluorescence in situ hybridization demonstrated positivity for ETV6-NTRK3 fusion in 4 cases. Although oral SC is rare, pathologists should be aware of the histologic overlap between the SC and other salivary gland neoplasms such as ACC and MEC. A judicious application of IHC staining would aid in diagnosis. SC should be considered in the differential diagnosis for intraoral salivary gland tumors.

Mammary analogue secretory carcinoma: An Indian experience of a novel entity

Aims

To explore clinical, histopathological and immunohistochemistry (IHC) features of mammary analogue secretory carcinoma (MASC) with systematic literature review.

Settings and Design

Hospital based cross-sectional study.

Subjects and Methods

The data of all cases of MASC diagnosed over a period of 1 year i.e., from July 2017 to July 2018 were retrieved. The haematoxylin and eosin (H and E) sections, and IHC sections were studied. A strict histological and recently updated criteria were applied and patients with a confirmed diagnosis of MASC were included in the study. A systematic literature review was conducted by searching the PubMed and National Centre for Biotechnology Information database.

Statistical Analysis Used

Microsoft Excel 2010.

Results

The present case series is 27th in the English literature and 1stcase series describing its histopathology in the Indian literature. The mean age of presentation is 43 years. Female preponderance was found i.e., M:F ratio of 0.5.

Conclusion

Histopathology and if necessary, followed by IHC is required for the confirmation of diagnosis of MASC. We should be aware about this recently described entity which is usually mistaken for other low grade salivary gland carcinomas like Acinic cell carcinoma (AciCC) and Mucoepidermoid carcinoma (MEC). The knowledge about its typical morphology, high degree of suspicion and IHC confirmation with both S-100 and Mammaglobin help in precise diagnosis.

Expanding the Molecular Spectrum of Secretory Carcinoma of Salivary Glands With a Novel VIM-RET Fusion

BACKGROUND

Secretory carcinoma (SC), originally described as mammary analogue SC, is a predominantly low-grade salivary gland neoplasm characterized by a recurrent t(12;15)(p13;q25) translocation, resulting in ETV6-NTRK3 gene fusion. Recently, alternative ETV6-RET, ETV6-MAML3, and ETV6-MET fusions have been found in a subset of SCs lacking the classic ETV6-NTRK3 fusion transcript, but still harboring ETV6 gene rearrangements.

DESIGN

Forty-nine cases of SC revealing typical histomorphology and immunoprofile were analyzed by next-generation sequencing using the FusionPlex Solid Tumor kit (ArcherDX). All 49 cases of SC were also tested for ETV6, RET, and NTRK3 break by fluorescence in situ hybridization and for the common ETV6-NTRK3 fusions using reverse transcription polymerase chain reaction.

RESULTS

Of the 49 cases studied, 37 (76%) occurred in the parotid gland, 7 (14%) in the submandibular gland, 2 (4%) in the minor salivary glands, and 1 (2%) each in the nasal mucosa, facial skin, and thyroid gland. SCs were diagnosed more frequently in males (27/49 cases; 55%). Patients' age at diagnosis varied from 15 to 80 years, with a mean age of 49.9 years. By molecular analysis, 40 cases (82%) presented the classic ETV6-NTRK3 fusion, whereas 9 cases (18%) revealed an alternate fusion. Of the 9 cases negative for the ETV6-NTRK3 fusion, 8 cases presented with ETV6-RET fusion. In the 1 remaining case in the parotid gland, next-generation sequencing analysis identified a novel VIM-RET fusion transcript. In addition, the analysis indicated that 1 recurrent high-grade case in the submandibular gland was positive for both ETV6-NTRK3 and MYB-SMR3B fusion transcripts.

CONCLUSIONS

A novel finding in our study was the discovery of a VIM-RET fusion in 1 patient with SC of the parotid gland who could possibly benefit from RET-targeted therapy. In addition, 1 recurrent high-grade case was shown to harbor 2 different fusions, namely, ETV6-NTRK3 and MYB-SMR3B. The expanded molecular spectrum provides a novel insight into SC oncogenesis and carries important implications for molecular diagnostics, as this is the first SC-associated translocation with a non-ETV6 5' fusion partner. This finding further expands the definition of SC while carrying implications for selecting the appropriate targeted therapy.

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

AIMS

Secretory carcinoma (SC) (synonym: mammary analogue secretory carcinoma) is a low-grade salivary gland tumour that occurs in both major and minor salivary glands. SC is known for its wide morphological, architectural and immunohistochemical spectrum, which overlaps with those of several salivary gland neoplasms, including acinic cell carcinoma (AciCC) and intercalated duct-type intraductal carcinoma (IDC) in major salivary glands, and polymorphous adenocarcinoma (PAC) in minor salivary glands. These tumours share with SC some morphological features and SOX10 immunoreactivity; also, with the exception of AciCC, they all coexpress S100 and mammaglobin.

METHODS AND RESULTS

We compared MUC4 and mammaglobin expression in 125 salivary gland carcinomas (54 genetically confirmed SCs, 20 AciCCs, 21 PACs, and 30 IDCs) to evaluate the potential of these two markers to differentiate these entities. Moderate to strong diffuse MUC4 positivity was detected in 49 SCs (90.7%), as compared with none of the IDCs and PACs. In contrast, mammaglobin was frequently expressed in SCs (30 of 36 cases; 83.3%), IDCs (24/28; 85.7%), and PACs (7/19; 36.8%). Two of three high-grade SCs lost MUC4 expression in the high-grade tumour component. No significant correlation was found between MUC4 expression and the fusion variant in SC (ETV6-NTRK versus non-ETV6-NTRK).

CONCLUSION

The results of our study identify MUC4 as a sensitive (90.7%) and specific (100%) marker for SC, with high positive (100%) and negative (93.4%) predictive values. Thus, MUC4 may be used as a surrogate for SC in limited biopsy material and in cases with equivocal morphology.

NR4A3 Immunohistochemistry Reliably Discriminates Acinic Cell Carcinoma from Mimics

Acinic cell carcinoma (AciCC) harbors a recurrent t(4;9)(q13;q31) translocation, which leads to upregulation of Nuclear Receptor Subfamily 4 Group A Member 3 (NR4A3). Previous work on tissue microarrays suggests that NR4A3 immunohistochemistry (IHC) may be useful in the diagnosis of AciCC. Thus far, only a single study has evaluated the utility of NR4A3 immunohistochemistry (IHC) in the diagnosis of AciCC, using a tissue microarray to assess most non-AciCC tumor types. Herein we evaluate the diagnostic performance of NR4A3 IHC for AciCC in a large cohort of 157 salivary gland tumors, using whole tissue sections. The cohort consisted of 37 AciCC (6 of them (16%) with high grade transformation), 30 secretory carcinomas (SC), and 90 additional salivary gland tumors, including mucoepidermoid carcinomas (MEC), polymorphous adenocarcinomas (PAC), pleomorphic adenomas (PA), salivary duct carcinomas (SDC), and adenoid cystic carcinomas (AdCC). NR4A3 nuclear staining by IHC was considered positive if present in more than 5% of tumor cells. Overall, 92% of AciCC (34/37) expressed NR4A3 by IHC, with strong (89%) or moderate (3%) nuclear staining, yielding a sensitivity of 92%. IHC detected NR4A3 expression in all cases of recurrent/metastatic AciCC and tumors with high grade transformation. Importantly, all SC were negative for NR4A3 IHC, with no staining in 28/30 cases and weak focal staining, in < 5% of cells, in 2/30 (7%). Similarly, all MEC (20/20), SDC (20/20) and AdCC (10/10) were negative for NR4A3 by IHC, as were most PA (18/20; 15%) and PAC (18/20; 5%). Two PA and two PAC showed multifocal expression of NR4A3 in more than 5% of cells, of weak intensity in 3 cases and moderate in 1 PAC, yielding an overall specificity of 97% for NR4A3 IHC for the diagnosis of AciCC. In conclusion, NR4A3 is a highly sensitive and specific immunohistochemical marker for AciCC; moderate to strong and/or diffuse NR4A3 expression is a consistent and diagnostic feature of AciCC.

Salivary Secretory Carcinoma Harboring a Novel ALK Fusion: Expanding the Molecular Characterization of Carcinomas Beyond the ETV6 Gene

Secretory carcinoma (SC) of the salivary glands is a low-grade carcinoma characterized by a well-defined morphology and immunohistochemical features. ETV6-NTRK3 fusions are detected in the great majority of SCs. Recently, other partners fused to ETV6 have been documented in a small portion of SCs, suggesting the presence of alternative genetic fusion. In this study, we examined the genetic fusion of 9 SCs using fluorescence in situ hybridization, reverse transcription-polymerase chain reaction, and next-generation sequencing (ArcherDx). Classic ETV6 exon 5-NTRK3 exon 15 fusion was detected in 8 of 9 SCs. The remaining tumor was negative for the ETV6-NTRK3 fusion but harbored a novel fusion, CTNNA1 exon 11-ALK in exon 20. Immunohistochemically, pan-TRK was positive in 8 tumors with ETV6-NTRK3 fusion but negative in an ALK-rearranged SC, while ALK was positive only in the ALK-rearranged tumor. Histologically, the ALK-rearranged tumor showed dominant macrocystic architecture. In conclusion, we found a case of SC with CTNNA1-ALK fusion. Because ALK fusion after exon 20 on the ALK side (upstream of the tyrosine kinase domain) has been reported to activate a carcinogenic kinase in various ALK-rearranged tumors, ALK inhibitors may be a possible therapeutic option for ALK-rearranged SC. In addition, ALK immunohistochemistry can be a screening tool for ALK-rearranged SC. This study also expands the molecular spectrum of this tumor beyond the ETV6 gene.

Expression of upstream and downstream targets of mTOR pathway in seven cases of secretory carcinoma of salivary gland origin

PURPOSE

To investigate the expression of upstream and downstream targets of mTOR signalling pathway in the secretory carcinoma of salivary gland origin (SCsg).

METHODS

Seven cases of secretory carcinoma diagnosed by a combination of immunohistochemistry and/or molecular testing were retrieved from our pathology files. For comparison purposes, 27 other salivary carcinomas were selected. Immunohistochemical staining was performed against phospho-Akt, PTEN, phospho-mTOR, phospho-4E-BP, eIF4E and phospho-S6 ribosomal protein.

RESULTS

With the exception of Akt, all the other proteins were present at some level in the SCsg and in other salivary carcinomas. PTEN was diffusely expressed in 57.1% of SCsg, but only in 14.8% of other salivary carcinomas. mTOR is expressed in more than half of the cases both for SCsg and other salivary tumour types. Most cases of SCsg showed negative expression for S6 ribosomal protein (71.4%) and 4E-BP1 (57.1%). For both groups evaluated, eIF4E was the most expressed protein.

CONCLUSION

SCsg shows different expression patterns for the mTOR signalling molecules, but only eIF4E was highly expressed. This may suggest alternative signalling pathways other than Akt and mTOR in this group of tumours.

Usefulness of immunohistochemistry to distinguish between secretory carcinoma and acinic cell carcinoma in the salivary gland

Secretory carcinoma (SC) of the salivary gland is a relatively newly described disease, separate from acinic cell carcinoma (ACC), which frequently displays ETV6-NTRK3 gene fusion. However, the differences between SC and ACC remain unclear. Here, histological reevaluation of 12 formerly diagnosed ACC cases was performed, which yielded a new diagnosis of SC in four cases due to a lack of obvious acinar-like cells. Immunohistochemically, phosphorylated signal transducer and activator of transcription 5 (p-STAT5) was expressed in SC but not in ACC, whereas discovered on GIST-1 (DOG1) was expressed in ACC but not in SC. Molecular analysis was possible in three SC cases, of which two showed the ETV6-NTRK3 fusion transcript on reverse-transcription polymerase chain reaction, as well as breaks in the ETV6 gene on fluorescence in situ hybridization. However, the remaining SC cases did not show this fusion transcript. Recently, several reports have suggested that SC might not be adequately diagnosed if the focus is placed solely on the ETV6-NTRK3 fusion gene due to genetic diversity. In this regard, immunohistochemistry of p-STAT5 and DOG1 is expected to be a useful alternative diagnostic tool to discriminate SC from ACC.

An Algorithmic Immunohistochemical Approach to Define Tumor Type and Assign Site of Origin

Immunohistochemistry represents an indispensable complement to an epidemiology and morphology-driven approach to tumor diagnosis and site of origin assignment. This review reflects the state of my current practice, based on 15-years' experience in Pathology and a deep-dive into the literature, always striving to be better equipped to answer the age old questions, "What is it, and where is it from?" The tables and figures in this manuscript are the ones I "pull up on the computer" when I am teaching at the microscope and turn to myself when I am (frequently) stuck. This field is so exciting because I firmly believe that, through the application of next-generation immunohistochemistry, we can provide better answers than ever before. Specific topics covered in this review include (1) broad tumor classification and associated screening markers; (2) the role of cancer epidemiology in determining pretest probability; (3) broad-spectrum epithelial markers; (4) noncanonical expression of broad tumor class screening markers; (5) a morphologic pattern-based approach to poorly to undifferentiated malignant neoplasms; (6) a morphologic and immunohistochemical approach to define 4 main carcinoma types; (7) CK7/CK20 coordinate expression; (8) added value of semiquantitative immunohistochemical stain assessment; algorithmic immunohistochemical approaches to (9) "garden variety" adenocarcinomas presenting in the liver, (10) large polygonal cell adenocarcinomas, (11) the distinction of primary surface ovarian epithelial tumors with mucinous features from metastasis, (12) tumors presenting at alternative anatomic sites, (13) squamous cell carcinoma versus urothelial carcinoma, and neuroendocrine neoplasms, including (14) the distinction of pheochromocytoma/paraganglioma from well-differentiated neuroendocrine tumor, site of origin assignment in (15) well-differentiated neuroendocrine tumor and (16) poorly differentiated neuroendocrine carcinoma, and (17) the distinction of well-differentiated neuroendocrine tumor G3 from poorly differentiated neuroendocrine carcinoma; it concludes with (18) a discussion of diagnostic considerations in the broad-spectrum keratin/CD45/S-100-"triple-negative" neoplasm.

Characterization of novel genetic alterations in salivary gland secretory carcinoma

Secretory carcinoma is a salivary gland tumor with a characteristic chromosomal translocation that results in an ETV6-NTRK3 fusion gene. Secretory carcinoma shows relatively frequent rates of lymph-node metastasis and tumor recurrence and has a characteristic histology. Except for the ETV6 translocation, genomic alterations in secretory carcinoma have not been reported. In the present study, we characterized the novel recurrent genetic mutations of secretory carcinoma. On the basis of histology, immunohistochemistry, and ETV6 gene break-apart fluorescence in situ hybridization assays, 22 tumors were classified as secretory carcinomas (19 ETV6 translocation-positive and 3 ETV6 translocation-negative secretory carcinomas) and their clinicopathologic characteristics were reviewed. Targeted deep sequencing analyses were performed on 20 secretory carcinomas (17 ETV6 translocation-positive and 3 ETV6 translocation-negative secretory carcinomas) to investigate their genetic alterations. The A16V (C→T) mutation in PRSS1, which encodes a cationic trypsinogen and has a mutation associated with hereditary pancreatitis and pancreatic adenocarcinoma, was observed in 40% (8/20) (7/17 of ETV6 translocation-positive and 1/3 of ETV6 translocation-negative secretory carcinomas). Pathogenic variants of MLH1, MUTYH, and STK11 were also identified. Variants of uncertain significance included mutations in KMT5A. These novel characteristic genetic alterations may advance current understandings of secretory carcinoma tumorigenesis and progression, leading to improved diagnoses and treatment strategies.

Secretory Carcinoma of Salivary Gland with High-Grade Histology Arising in Hard Palate: A Case Report

Secretory carcinoma (SC) is a recently described salivary gland tumor reported in the fourth edition of World Health Organization classification of head and neck tumors. SC is characterized by strong S-100 protein, mammaglobin, and vimentin immunoexpression, and harbors a t(12;15)(p13;q25) translocation which leads to ETV6-NTRK3 fusion product. Histologically, SC displays a lobulated growth pattern and is often composed of microcystic, tubular, and solid structures with abundant eosinophilic homogenous or bubbly secretion. SC is generally recognized as low-grade malignancy with low-grade histopathologic features, and metastasis is relatively uncommon. In this case, we described a SC of hard palate that underwent high grade transformation and metastasis to the cervical lymph node in a 54-year-old patient. In addition, this case showed different histological findings between primary lesion and metastasis lesion. Therefore, the diagnosis was confirmed by the presence of ETV6 translocation. Here, we report a case that occurred SC with high-grade transformation in the palate, and a review of the relevant literature is also presented.

[Secretory carcinoma of the salivary gland (mammary analogue secretory carcinoma) in children]

Secretory carcinoma of the salivary gland is a tumor that was first described less than 10 years ago and that mainly occurs in the parotid salivary gland in the elderly. Analyzing the literature over 8 years since the first description of the tumor identifies the main clinical, morphological, and genetic signs of the diagnosis of secretory carcinoma with a focus on the pediatric population. Four new cases of secretory carcinoma of the salivary glands, which have been diagnosed in children of the youngest age encountered in the literature, are also described.

A Challenging Case of Mammary Analogue Secretory Carcinoma: Case Study with Ultrastructural and Cytogenetic Correlation

Mammary analogue secretory carcinoma (MASC) is a rare salivary gland tumor analogous to secretory carcinoma of the breast. The diagnosis of MASC can be challenging due to substantial morphologic and immunohistochemical similarities with other salivary gland tumors. The differential diagnosis of MASC is broad and includes intraductal carcinoma, acinic cell carcinoma, and adenocarcinoma, not otherwise specified. Although molecular testing for ETV6 gene rearrangement is characteristic of MASC and has not been shown in any other salivary gland tumor, a particular challenge arises when such testing is unavailable, or when molecular testing for ETV6 gene rearrangement is negative in a suspected case of MASC. Our study presents the diagnostic workup of a challenging case of MASC with immunohistochemistry, electron microscopy, and cytogenetic studies performed to resolve the diagnosis.

Mammary analogue secretory carcinoma of the minor salivary gland: report of two cases

Mammary analogue secretory carcinoma (MASC) is a recently described salivary gland tumour notable for a balanced chromosomal translocation t(12;15)(p13;q25) that contributes to ETV6 gene rearrangements. It was first reported in 2010 by Skalova et al. with histological features resembling secretory carcinoma of the breast and was acknowledged and referred to as "secretory carcinoma" in the updated 2017 WHO classification. It is reported that MASC accounts for <0.3% of all salivary gland tumours, with a finite number of published reports on it. MASC has a range of histological features and clinical behaviours. The histopathological diagnosis of MASC can be difficult with current immunohistochemical methods. One case was located in the left palate, and 1 case was located in the soft palate. The maximum diameter of the tumour was 1.4~3.7 cm. CT demonstrated a mass that had not invaded into the palate bone, and the patients underwent palate neoplasm expanded ectomy without neck dissection or postoperative radiation therapy. Histopathological examination revealed that the tumour cells consisted of a mixed arrangement of microcystic, papillary-cystic, follicular, and solid lobular growth patterns. Eosinophilic cytoplasm and intraluminal or intracytoplasmic colloid-like secretions were observed. The final pathology confirmed the diagnosis of MASC with immunohistochemically neoplastic cells staining positive for S-100 and mammaglobin. The patients were asymptomatic at their 12-month follow up. More studies are needed to identify the typical behaviour of this tumour and establish the standard treatment regimen. This study aims to reinforce the awareness of this tumour by analysing its clinicopathologic features, immunophenotype, and diagnosis.

Ancillary testing in salivary gland cytology: A practical guide

Salivary gland cytology is challenging, and historically the role of ancillary testing has been limited. However, numerous molecular/genetic advances in the understanding of salivary gland neoplasms during the last decade have facilitated the development of many useful diagnostic markers, such as PLAG1 and HMGA2 immunohistochemistry for pleomorphic adenoma and ETV6 fluorescence in situ hybridization for secretory carcinoma. Numerous salivary gland neoplasms are characterized by specific molecular/genetic alterations, many of which can be identified on cytologic preparations by karyotype analysis, fluorescence in situ hybridization, or immunohistochemical surrogates. Next-generation sequencing also has potential diagnostic applications, although to the authors' knowledge it currently has no routine role in salivary cytology. The primary goal of salivary fine-needle aspiration (FNA) is to facilitate appropriate clinical management. Ancillary testing has greatly enhanced the ability for accurate classification as per The Milan System for Reporting Salivary Gland Cytopathology and allows for the definitive diagnosis of many salivary FNA specimens, and also may resolve diagnostic uncertainty for FNAs that may be classified in The Milan System for Reporting Salivary Gland Cytopathology categories of salivary gland neoplasm of uncertain malignant potential or suspicious for malignancy. This review provides an updated discussion of the molecular/genetic features of the more commonly encountered salivary neoplasms by FNA, and discusses the application of available diagnostic immunohistochemical and molecular tests in salivary gland cytology.

Molecular Profiling of Salivary Gland Intraductal Carcinoma Revealed a Subset of Tumors Harboring NCOA4-RET and Novel TRIM27-RET Fusions: A Report of 17 cases

Intraductal carcinoma (IC) is the new World Health Organization designation for tumors previously called "low-grade cribriform cystadenocarcinoma" and "low-grade salivary duct carcinoma." The relationship of IC to salivary duct carcinoma is controversial, but they now are considered to be distinct entities. IC is a rare low-grade malignant salivary gland neoplasm with features similar to mammary atypical ductal hyperplasia or ductal carcinoma in situ, that shows diffuse S100 protein and mammaglobin positivity and is only partially defined genetically. (Mammary analogue) secretory carcinoma harboring ETV6-NTRK3, and in rare cases ETV6-RET fusion, shares histomorphologic and immunophenotypical features with IC. Recently, RET rearrangements and NCOA4-RET have been described in IC, suggesting a partial genetic overlap with mammary analogue secretory carcinoma. Here, we genetically characterize the largest cohort of IC to date to further explore this relationship. Seventeen cases of IC were analyzed by next-generation sequencing using the FusionPlex Solid Tumor kit (ArcherDX). Identified fusions were confirmed using fluorescence in situ hybridization break apart and, in some cases, fusion probes, and a reverse transcription polymerase chain reaction designed specifically to the detected breakpoints. All analyzed cases were known to be negative for ETV6 rearrangement by fluorescence in situ hybridization and for ETV6-NTRK3 fusion by reverse transcription polymerase chain reaction. Next-generation sequencing analysis detected a NCOA4-RET fusion transcript joining exon 7 or 8 of NCOA4 gene and exon 12 of RET gene in 6 cases of intercalated duct type IC; and a novel TRIM27-RET fusion transcript between exons 3 and 12 in 2 cases of salivary gland tumors displaying histologic and immunohistochemical features typical of apocrine IC. A total of 47% of IC harbored a fusion involving RET. In conclusion, we have confirmed the presence of NCOA4-RET as the dominant fusion in intercalated duct type IC. A novel finding in our study has been a discovery of a subset of IC patients with apocrine variant IC harboring a novel TRIM27-RET.

Clinical characteristics of acinic cell carcinoma and secretory carcinoma of the parotid gland

PURPOSE

Mammary analogue secretory carcinoma (SC) of the parotid gland is a relatively uncommon cancer associated with the ETV6-NTRK3 fusion product similar to breast cancer. The clinical characteristics and outcome of treatment were reviewed for patients with this tumor at our hospital.

METHODS

In this retrospective case series, 24 patients with a diagnosis of acinic cell carcinoma (AcCC) of the parotid gland were classified as having either SC or AcCC based on analysis of the ETV6-NTRK3 fusion gene. These two groups were compared with respect to their clinical and imaging characteristics (MRI/US), cytologic findings, accuracy of fine-needle aspiration cytology and frozen section, treatment outcomes, and immunohistochemical findings.

RESULTS

Based on re-classification by ETV6-NTRK3 fusion gene analysis, the diagnosis was SC in 14 patients and AcCC in 10 patients. The SC group had a significantly higher proportion of male patients and was also significantly younger than the AcCC group. Imaging studies revealed that SC was significantly more likely to show internal heterogeneity. Correct grading of both tumors was comparable by fine needle aspiration, with the rate being 60% for AcCC and 50% for SC. Diagnosis by frozen section biopsy diagnosis obtained the correct grade in 90% of the AcCC group and 93% of the SC group.

CONCLUSIONS

In 24 patients previously diagnosed with AcCC, re-analysis of the ETV6-NTRK3 fusion product indicated that 14 patients actually had SC. Although AcCC and SC show similarities of their biological aggressiveness and prognosis, patients with SC were significantly more likely to be male and younger.

Mammary analogue secretory carcinoma presenting as a cystic parotid mass

We present a case of a 63-year-old male with an 8-year history of a left-sided cystic facial mass which recurred despite multiple drainage procedures. Imaging findings showed a cystic mass in the left parotid gland and it was surgically resected. Pathology confirmed it to represent a mammary analogue secretory carcinoma, a relatively newly described entity. This case illustrates that mammary analogue secretory carcinoma can masquerade as a cyst within the parotid gland.

Immunohistochemistry with a pan-TRK antibody distinguishes secretory carcinoma of the salivary gland from acinic cell carcinoma

AIMS

Secretory carcinoma (previously known as mammary analogue secretory carcinoma) is characterised by ETV6 rearrangements, most often ETV6-NTRK3 fusion. Given its histological overlap with other salivary gland tumours, secretory carcinoma can be difficult to diagnose without genetic confirmation. A recently developed pan-TRK antibody shows promise for identifying tumours with NTRK fusions. The aim of this study was to evaluate the utility of pan-TRK immunohistochemistry in distinguishing secretory carcinoma from mimics.

METHODS AND RESULTS

We examined whole-tissue sections from 86 tumours, including 14 secretory carcinomas (12 parotid primaries and one buccal primary, and one metastasis; five with ETV6 rearrangement confirmed by fluorescence in-situ hybridisation, and one with ETV6-NTRK3 fusion and one with ETV6-RET fusion detected by targeted sequencing), 14 acinic cell carcinomas, 18 polymorphous adenocarcinomas, 20 low-grade mucoepidermoid carcinomas, and 20 pleomorphic adenomas. Immunohistochemistry was performed with a pan-TRK rabbit monoclonal antibody. Pan-TRK staining was detected in nine (64%) secretory carcinomas, all with a nuclear pattern and four with diffuse staining (>50% of cells). Among other tumour types, pan-TRK immunoreactivity was observed in all (100%) pleomorphic adenomas (particularly myoepithelial cell-rich, myxoid areas), 15 (83%) polymorphous adenocarcinomas, and four (20%) low-grade mucoepidermoid carcinomas, all with predominantly membranous/cytoplasmic immunoreactivity; only six cases showed focal (<10%) nuclear staining. All acinic cell carcinomas were entirely negative.

CONCLUSIONS

Although pan-TRK expression is not entirely sensitive or specific for secretory carcinoma, nuclear staining distinguishes secretory carcinoma from mimics. Acinic cell carcinomas are negative for pan-TRK, though membranous expression of TRK is common in other salivary gland neoplasms. The lack of pan-TRK immunoreactivity in a subset of secretory carcinomas may suggest non-NTRK fusion partners.

The significance of the morphological and immunological characteristics in the diagnosis of parotid mammary analogue secretory carcinoma: five case reports and a review of the literature

Mammary analogue secretory carcinoma (MASC) of the salivary glands is rarely reported. In this article, the histopathological features of 5 cases of parotid MASC were retrospectively analyzed. AB/PAS and immunohistochemical staining of S-100, mammaglobin and P63 was performed, which were validated by the ETV6-fluorescent FISH detection of NTRK3 gene. The tumors were composed of two kinds of tumor cells. One kind of cells was rich in cytoplasms, transparent or vacuole-like, partial basophilic double tropism, but another type of cellular cytoplasm was acidophilic. The karyotype was consistent between two types of tumors in the vacuolar pattern. Although the tumor cells were arranged in different forms, the cystic (capsule or microcapsule) structures were constantly observed. Two kinds of tumor cells produced different secretions, which were distributed among the tumor cells. Tumor tissues were divided by hardened collagen interstitial, even in the infiltration lesion, collagen and tumor cells mass was also inseparable. The expression of mammaglobin and S-100 significantly differed between the two types of tumor cells. These characteristics contribute to the differential diagnosis of MASC. ETV6-NTRK3 gene detection can be applied in the diagnosis of atypical cases, but it should not be done routinely.

Secretory Carcinoma of the Parotid: Making the Correct Diagnosis of a Rare Salivary Gland Carcinoma When Molecular Biology Testing Is Not Available

Secretory carcinoma (SC) is a recently described entity occurring in the salivary glands. Before its description, SC was frequently classified as acinic cell carcinoma (ACC) or adenocarcinoma, not otherwise specified. Its particular histopathological and immunohistochemical characteristics are reminiscent of breast secretory carcinoma. Moreover, it displays a characteristic t(12;15) (p13;q25) translocation that results in the ETV6-NTRK3 gene fusion. This translocation has not been reported in any other salivary gland carcinoma. Identification of the t(12;15) (p13;q25) translocation is the gold standard for diagnosis, although some cases that do not present this specific translocation have already been reported. In such cases, diagnosis is challenging. In addition, some diagnostic pathology laboratories lack the resources to perform the molecular analysis to diagnose SC. In this scenario, morphology and immunohistochemistry are fundamental. Therefore, we report a case emphasizing the typical morphology of SC and its immunochemical profile to establish a final diagnosis without molecular biology tests. This case aims to demonstrate the importance of recognizing the typical presentation of a rare tumor so that clinicians will be informed or reminded of it and consider this entity among the differential diagnoses, when necessary. Moreover, in low-resource settings where molecular analysis is not available, being familiar enough with the histology of this tumor and using the immunoprofile as a key tool for differential diagnosis would be of great importance in establishing the correct diagnosis. The differential diagnosis includes, above all, acinic cell carcinoma and other salivary neoplasms such as intraductal carcinoma, low-grade mucoepidermoid carcinoma, and adenocarcinoma, not otherwise specified, which is actually a rule-out diagnosis.

Novel gene fusions in secretory carcinoma of the salivary glands: enlarging the ETV6 family

Secretory carcinoma (SC) of the salivary gland is a low-grade malignancy associated with a well-defined clinical, histologic, immunohistochemical, and cytogenetic signature. Although the t(12;15) (p13;q25) translocation resulting in an ETV6-NTRK3 gene fusion is well documented, advances in molecular profiling in salivary gland tumors have led to the discovery of RET as another ETV6 gene fusion partner in SC. Here, we applied an RNA-based next-generation sequencing (NGS) approach for fusion detection on 14 presumed SC. The cases included 7 SC with classic ETV6-NTRK3 gene fusion and 3 SC harboring ETV6-RET gene fusion. In addition, 2 cases revealed a NCOA4-RET gene fusion and were subsequently reclassified as intraductal carcinomas. One case with an unusual dual-pattern morphology revealed a novel translocation involving ETV6, NTRK3, and MAML3 gene rearrangements. Interestingly, no ETV6-NTRK3 or ETV6-RET SC was ever documented to have this unique dual-pattern morphology or harbor a MAML3 mutation. The remaining case had no detected chromosomal abnormalities. Advances in molecular profiling of SC have led to the discovery of novel fusion partners such as RET and now MAML3. Further molecular characterization of salivary gland neoplasms is needed as these mutations may present alternative therapeutic targets in patients with these tumors.

Secretory carcinoma of the major salivary gland: Provincial population-based analysis of clinical behavior and outcomes

BACKGROUND

Our aim was to identify the number of cases of secretory carcinoma (SC) of the major salivary gland in a population-based cohort and review its clinical behavior with long-term follow-up.

METHODS

All malignant salivary gland tumors (MSGTs) diagnosed between 1980 and 2014 were assessed for histological features compatible with SC and 140 were selected for further analysis.

RESULTS

Twenty two new cases of SC were identified, 19 of which were originally classified as acinic cell carcinoma, and 3 as adenocarcinoma, not otherwise specified (NOS). Lymph node involvement was less common in SC tumors (5%) than in the control group (11%). Disease recurrence was seen less frequently in SC (9%) than the control group (20%). Mean disease-free survival was 192 months for SC compared with 162 months for controls (P = 0.15).

CONCLUSION

The clinical course of SC is typically indolent with a low risk of relapse not significantly different from other low-grade MSGT.

Secretory carcinoma: the eastern Canadian experience and literature review

Background

Secretory Carcinoma (SC) is a recently described malignancy affecting salivary glands of the head and neck, with a paucity of evidence regarding the natural history, morbidity, and mortality. This study aimed to investigate the current treatment options utilized for SC, as well as its presentation and outcomes.

Methods

This study is a retrospective case series and includes patients diagnosed with SC at four Maritime Canadian institutions. Literature review of patient outcomes following treatment of SC is also included.

Results

Thirteen patients were identified. Parotid was the most common subsite (69%), followed by minor salivary gland (23%) and submandibular gland (8%). All patients were S100 positive and had at least one additional positive confirmatory stain, including mammaglobin, CK7, or vimentin. Two patients had N2b disease. All patients were treated with primary surgery, and four were offered adjuvant radiotherapy. There was one instance of locoregional recurrence, and one of metastasis. Three patients displayed perineural invasion on pathology, and one patient displayed lymphovascular invasion.

Conclusion

Secretory Carcinoma remains understudied regarding its natural history, presentation, and treatment options. This study is the largest single case series in Canada, and highlights the young age and possible aggressiveness of SC. As well, we provide the most comprehensive literature review to date, with a focus on treatment and outcomes for this disease entity.

Electronic supplementary material

The online version of this article (10.1186/s40463-018-0315-6) contains supplementary material, which is available to authorized users.

Updates in Salivary Gland Fine Needle Aspiration Biopsy: The Use of the Milan System and Ancillary Testing

Salivary gland fine needle aspiration biopsies remain common specimens seen by most cytology services. The diagnostic diversity and overlap between many of the lesions seen with these biopsies impart many challenges for the cytopathologist, rendering most specific diagnoses impossible with cytology alone. Here, the use of the Milan System for the classification of salivary gland fine needle aspiration biopsy FNAB is discussed, together with the potential use of ancillary testing in arriving at definitive diagnoses.