Mammaglobin and S-100 immunoreactivity in salivary gland carcinomas other than mammary analogue secretory carcinoma

ETV6 Molecular Heterogeneity in Salivary Secretory Carcinoma: A Case Series Report and Literature Review

BACKGROUND

ETV6 gene rearrangement is the molecular hallmark of secretory carcinoma (SC), however; the nature, frequency, and clinical implications of atypical ETV6 signal patterns by fluorescence in situ hybridization (FISH) has not yet been systematically evaluated in salivary gland neoplasms.

METHODS

The clinical, histopathologic, immunohistochemical and molecular features of seven salivary SCs, including four cases with atypical ETV6 FISH patterns, were retrospectively analyzed along with a critical appraisal of the literature on unbalanced ETV6 break-apart in SCs.

RESULTS

The patients were four males and three females (31-70 years-old). Five presented with a painless neck mass and two patients with recurrent disease had a history of a previously diagnosed acinic cell carcinoma of the buccal mucosa. Histologically, there were varied combinations of microcystic, papillary, tubular, and solid patterns. All tumors were diffusely positive for S100 and/or SOX10, while 2 cases also showed luminal DOG1 staining. Rearrangement of the ETV6 locus was confirmed in 5/7 cases, of which 3 cases showed classic break-apart signals, 1 case further demonstrated duplication of the ETV6 5`end and the other loss of one copy of ETV6. Two cases harbored ETV6 deletion without rearrangement. Two of the 4 cases with atypical ETV6 FISH patterns represented recurrent tumors, one with widespread skeletal muscle involvement, bone and lymphovascular invasion. Surgical treatment resulted in gross-total resection in all 7 cases, with a median follow up of 9.5 months post-surgery for primary (n = 3) and recurrent disease (n = 1).

CONCLUSION

Duplication of the distal/telomeric ETV6 probe represented the most common (26/40; 65%) variant ETV6 break-apart FISH pattern in salivary SC reported in the literature and appears indicative of an aggressive clinical course.

Clinicopathological Features of 26 Intraoral Polymorphous Adenocarcinomas from a Single Brazilian Institution

PURPOSE

This study describes a large, well-documented case series of salivary gland polymorphous adenocarcinomas (PAC) from a single Brazilian center.

METHODS

Demographic data, clinical presentation, histopathological and immunohistochemical features from 26 cases of PAC were analyzed and discussed in detail.

RESULTS

Most patients were females (n = 21), with a ratio of 1:4.2 (male: female) with a mean age of 58.8 years (ranging from 36 to 84 years). The most common clinical presentation was a fibrocollagenous, firm nodular lesion, with a mean size of 2.46 cm (ranging from 0.5 to 3 cm). Most lesions occurred on the palate (n = 16), followed by buccal mucosa (n = 3), upper lip (n = 3), buccal vestibule (n = 2) and alveolar ridge (n = 1). Histologically, various growth patterns were observed, including tubular, solid, cribriform, papillary, and cystic. Additionally, glomeruloid slit-like structures, mucous, and clear cells were noted. Surface papillary epithelial hyperplasia was observed in a few cases. Nine cases exhibited myxoid and collagenous areas, while two cases showed fusiform areas and another case demonstrated squamous differentiation. Clear cell predominance was noted in two cases, and peri- and intraneural invasion was seen in eight cases. Immunohistochemical analysis revealed positivity for S-100, p63 and CK7, and negativity for p40 in all cases. The Ki-67 proliferation index was markedly low in most cases, with a mean of 2.5%.

CONCLUSION

We have provided a broad, detailed description of the clinical and microscopic features of PAC in a large, Brazilian cohort. These findings, in a resource-limited area, may be quite useful for establishing a proper diagnosis.

PON3::LCN1 and HTN3::MSANTD3 Gene Fusions With NR4A3/NR4A2 Expression in Salivary Acinic Cell Carcinoma

Acinic cell carcinoma of the salivary gland (AciCC) is a low-grade carcinoma characterized by the overexpression of the transcription factor nuclear receptor subfamily 4 group A member 3 (NR4A3). AciCC has been the subject of a few molecular research projects. This study delves into AciCC's molecular landscape to identify additional alterations and explore their clinical implications. RNA sequencing and immunohistochemical staining for markers NR4A3/NR4A2, DOG-1, S100, and mammaglobin were utilized on 41 AciCCs and 11 secretory carcinoma (SC) samples. NR4A3 was evident in 35 AciCCs, while the residual 6 were NR4A3-negative and NR4A2-positive; SC samples were consistently NR4A3-negative. A novel fusion, PON3 exon 1- LCN1 exon 5, was detected in 9/41 (21.9%) AciCCs, exhibiting a classical histologic pattern with serous cell components growing in solid sheets alongside the intercalated duct-like component. Clinical follow-up of 39 patients over a median of 59 months revealed diverse prognostic outcomes: 34 patients exhibited no disease evidence, whereas the remaining 5 experienced poorer prognosis, involving local recurrence, lymph node, and distant metastasis, and disease-associated death, 4 of which harbored the PON3::LCN1 fusion. In addition, the HTN3::MSANTD3 fusion was recurrently identified in 7/41 AciCC cases. SC patients lacked both fusions. Immunohistochemistry uncovered differential expression of DOG-1, S100, and mammaglobin across samples, providing nuanced insights into their roles in AciCC. This study accentuates PON3::LCN1 and HTN3::MSANTD3 fusions as recurrent molecular events in AciCC, offering potential diagnostic and prognostic utility and propelling further research into targeted therapeutic strategies.

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.

Recent developments in the pathology of primary pulmonary salivary gland-type tumours

Primary pulmonary salivary gland-type tumours are rare neoplasms that are thought to arise from seromucinous glands that are located in the submucosa of large airways. These neoplasms have clinical and pathologic features that are distinct from other pulmonary neoplasms. The majority of primary pulmonary salivary gland-type tumours are malignant, with the most common entities being mucoepidermoid carcinoma, adenoid cystic carcinoma, and epithelial-myoepithelial carcinoma. Less commonly seen are myoepithelial carcinoma, hyalinizing clear cell carcinoma, acinic cell carcinoma, secretory carcinoma, salivary duct carcinoma, intraductal carcinoma, and polymorphous adenocarcinoma. Benign salivary gland-type tumours of the lung include pleomorphic adenoma and sialadenoma papilliferum. Morphologic, immunophenotypic, and molecular features of these neoplasms are largely similar to salivary gland tumours elsewhere, and therefore the exclusion of metastatic disease requires clinical and radiologic correlation. However, the differential diagnostic considerations are different in the lung. The distinction of salivary gland-type tumours from their histologic mimics is important for both prognostication and treatment decisions. Overall, salivary gland type-tumours tend to have a more favourable outcome than other pulmonary carcinomas, although high-grade variants exist for many of these tumour types. Recent advances in our understanding of the spectrum of salivary gland-type tumours reported in the lung and their diversity of molecular and immunohistochemical features have helped to refine the classification of these tumours and have highlighted a few differences between salivary gland-type tumours of the lung and those primary to other sites.

Bronchial oncocytic carcinoma in an adult: a case report and literature review

BACKGROUND

Lung salivary-type tumors originating from bronchial submucosal glands are rare, only four types of salivary gland-type tumors are listed in 2015 WHO classification of lung tumors. Here, we report a rare case of oncocytic carcinoma (OC) in the right main bronchus.

CASE PRESENTATION

A 34-year-old man presented to our hospital with a two-month history of recurrent hemoptysis and with one month of inspiratory dyspnea. Pulmonary function tests showed mild restrictive ventilatory dysfunction and severe diffusion dysfunction. Furthermore, the flow volume loop showed a variable extra-thoracic obstruction. Computed tomography (CT) of the chest revealed that a polypiform nodule of 13 mm in diameter was at the proximal right main bronchus. Testing for purified protein derivative was positive (category 2). The nodule was resected under bronchoscopy. The bronchial aspirate was negative for mycobacterium tuberculosis and tumor cells. The biopsy sample showed a solid and acinar predominant pattern with abundant eosinophilic cytoplasm. The bronchial mucosa was destroyed and replaced by tumor cells. The loose edematous stromal reaction could be seen in a local area. Immunohistochemically, tumor cells were positive for CK, EMA, Vimentin, CD117, CK7, S100, Mammaglobin and SOX10. Only scattered tumor cells were stained by basal cell markers, including CK5/6, P40 and P63. Electron microscopy revealed numerous swelling mitochondria with lacking mitochondrial cristae in tumor cells. Fluorescence in situ hybridization (FISH) testing for MAML2 and ETV6 rearrangement were negative. Next-generation sequencing analysis of 520 genes in the tissue biopsy specimen showed no somatic mutation. The diagnosis of OC was made. Subsequently, the patient underwent a right upper lobectomy with sleeve resection of the main bronchus and lymph dissection. No recurrent evidence was seen during two years of chest CT follow-up.

CONCLUSIONS

To our knowledge, this is the first case of primary OC in the bronchus. This patient has no recurrence during two years of follow-up, indicating that primary OC in the bronchus has the same favorable prognosis as in salivary glands. Moreover, complete excision and thorough sampling to know the invasive growth pattern is important to reach the correct diagnosis.

Identification of LMO2 as a new marker for acinic cell carcinoma of salivary gland

Background

The distinction between acinic cell carcinoma (ACC) and secretory carcinoma (SC) of the salivary gland is hampered by the lack of specific diagnostic markers. It is known the cytoplasm of glandular cells in the salivary gland immunohistochemically expresses LIM Domain Only 2 (LMO2). Herein, we aim to evaluate the expression status of LMO2 in a large cohort of tumors of the salivary gland, with an emphasis on its significance in the distinction of ACC and SC.

Methods

Immunohistochemical stains were performed to evaluate the expression of LMO2 in normal tissues and tumors of salivary gland.

Results

LMO2 was expressed in normal serous acinar cells of the salivary gland. We also found the cytoplasmic immunostaining of LMO2 was specific and sensitive for the recognition of ACCs including those with morphological overlaps with SCs, whereas the cytoplasmic expression of LMO2 was not detected in SCs.

Conclusions

LMO2 is useful for the recognition of ACC and is of potential value in distinguishing ACC from SC.

Cytopathological Findings of Secretory Carcinoma of the Salivary Gland and the Diagnostic Utility of Giemsa Staining

Secretory carcinoma is a salivary gland neoplasm first described as a mammary analogue secretory carcinoma by Skalova and redesignated as a secretory carcinoma in the 2017 World Health Organization Classification of Head and Neck Tumors. Secretory carcinoma diagnosis is reliant on specific cytological and histological findings and the detection of an ETV6-NTRK3 fusion gene. Here, we examined the clinical and cytopathological features of four cases of secretory carcinoma occurring in three males and a female, aged between 39 and 74 years. All four tumors involved the parotid gland, and were found to have the ETV6-NTRK3 fusion gene. Fine-needle aspiration-based cytology smears of all tumors displayed papillary and/or dendritic pattern clusters, some of which were associated with blood vessels. The neoplastic cells displayed enlarged nuclei with fine chromatin and small, distinct, single nucleoli. Furthermore, several neoplastic cells with a characteristic vacuolated cytoplasm were identified in each specimen. Giemsa staining revealed cytoplasmic vacuolation, intracytoplasmic metachromatic secretions and/or various sized metachromatic granules, and a background of metachromatic mucin in all four specimens. Given this, we conclude that these cytological findings, especially those of the Giemsa staining, might be helpful in the diagnosis of secretory carcinoma.

Practical immunohistochemistry in the classification of salivary gland neoplasms

Diagnosis of salivary gland neoplasms can be challenging for surgical pathologists due to low incidence of tumors as well as overlapping histologic features. On small biopsy, the most important information to be conveyed for clinical management is the distinction between a benign/low grade tumor and a high grade carcinoma. This review will discuss the differential diagnosis of salivary gland tumors based on four broad morphologic patterns: basaloid/tubular/cribriform, (micro)cystic/secretory/mucinous, solid-nested/clear-spindled, and oncocytic/oncocytoid. With the assistance of immunohistochemistry, demonstration of the number of cell types (mainly epithelial versus myoepithelial/basal) can further subclassify tumors within these morphologic categories. Additional tumor-specific immunomarkers are useful in some cases. Underlying tumor-specific genetic anomalies can be of value, however, immunohistochemical correlates are only available for some. When used judiciously, in the correct morphologic context, and with knowledge of their limitations, immunohistochemical stains can aid in differentiating tumors with similar morphology.

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.

Proliferative Activity of Myoepithelial Cells in of Mucoepidermoid Carcinoma

AIM: The aim of the study is to investigate the role of myoepithelial cells in the pathogenesis of mucoepidermoid carcinoma (MEC) using the double immunohistochemical staining; α _smooth muscle actin (_α-SMA)as specific marker for the myoepithelial cell differentiation and proliferative cell nuclear antigen (PCNA) as a marker for proliferative activity of myoepithelial cells. MATERIAL AND METHODS: Retrospective study of twenty salivary gland specimens (ten MEC and ten normal salivary glands) were studied using double immunohistochemical labeling for α _smooth muscle actin α-SMA) and proliferative cell nuclear antigen (PCNA). The SPSS statistical package was used for data analysis (IBM SPSS Statistics for Windows, Version 20.0, Released 2011, IBM Corp, and Armonk, NY, USA). RESULTS: In mucoepidermoid carcinomas, no positivity of α-SMA was seen in neoplastic cells (Frequent test), and it was just observed in the stroma of tumor, in the walls of blood vessels whereas, PCNA was positive, especially in high-grade tumors. In contrast, in normal salivary glands, the proliferating myoepithelial cells are stained by both α-SMA and PCNA. CONCLUSIONS: We believe that the myoepithelial cells have no a role in the development of mucoepidermoid carcinoma.

Differential diagnosis and treatment of salivary secretory carcinoma and acinic cell carcinoma

Secretory carcinoma (SC) and acinic cell carcinoma (AciCC) are two rare tumors originating in the salivary gland of the head and neck. Before the World Health Organization (WHO) classified SC as a new entity in 2017, the majority of SC cases were incorrectly diagnosed as AciCC. Indeed, they are similar in biological behaviors, clinical manifestations and histomorphological features. Especially, SC and zymogen granule-poor AciCC are difficult to differentiate, which brings a tough challenge in clinical diagnosis. This article provides an updated understanding of the differential diagnosis in SC and AciCC from two main perspectives: histopathology and molecular genetics. The targeted therapies for both tumors are also mentioned. It aims to give some hints in clinical diagnosis and treatment, in hopes that patients with adequate diagnosis could obtain the opportunityformore effective treatment.

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.

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.

Secretory carcinoma of salivary type in a lymph node presenting as a neck cyst diagnosed by cytology: A case report

Secretory carcinoma (SC) is a relatively recently described salivary gland adenocarcinoma characterized by ETV6-NTRK3 gene fusion and, in most cases, indolent clinical behavior. Morphologically, the tumor shows a glandular architecture and the presence of monophasic tumor cells with vacuolated cytoplasm, low-grade nuclear atypia, and mucin production, with possibly a tubular, papillary, or cystic arrangement. In this article, we describe a case of a 52-year old man with SC involving a neck lymph node clinically manifesting as a slowly growing cystic neck mass without recent proof of the primary tumor, but with a history of a parotid gland "cystadenopapilloma," which had been removed 35 years prior. A fine-needle aspiration biopsy revealed a diagnosis of SC. Subsequent histopathological examination after lymph node dissection confirmed the diagnosis. The tumor showed typical features of SC, including immunohistochemical positivity for NTRK and NTRK3 gene rearrangement, detected using in situ hybridization. We discuss that the tumor may be a late metastasis occurring 35 years after resection of undiagnosed salivary SC or a primary SC arising from heterotopic salivary tissue within a lymph node. Differential diagnostic considerations and review of relevant literature are included.

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.

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.

Immunohistochemical expression of mammaglobin in salivary duct carcinomas de novo and salivary duct carcinoma ex pleomorphic adenoma

Mammaglobin is expressed in breast and salivary gland secretory carcinomas; however, its expression in salivary duct carcinomas (SDCs) still not well established. Therefore, the aim of this study was to investigate the presence and distribution of mammaglobin immunoexpression in SDC ex-PA in different phases of the adenoma to carcinoma sequence evaluating its possible involvement in carcinogenesis and tumor progression, as well as to determine its expression in SDC de novo. Mammaglobin immunohistochemistry was performed in 84 SG tumors, including 41 pleomorphic adenomas (PA) without malignant transformation, 13 intracapsular SDC ex-PA, 5 frankly invasive SDC ex-PA, 25 SDC de novo and 10 secretory carcinomas. The reactions were qualitatively analyzed and digitally scored. Positive immunostaining for mammaglobin was observed in 37 out of 84 SG tumors evaluated (44.1%), but strong staining was consistently seen only in secretory carcinomas, SDC de novo and frankly invasive SDC ex-PA, while it was weaker in intracapsular SDC ex-PA and PA. In PA, mammaglobin expression was significantly associated with recurrence. This study has confirmed that the mammaglobin is commonly expressed in SDC de novo and secretory carcinomas. Its expression was higher in SDC ex-PA than in PA, suggesting that mammaglobin may play a role in its malignant transformation.

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 key radiologic and cytomorphologic features of oncocytic and oncocytoid lesions of the salivary gland

Oncocytic and oncocytoid lesions represent a distinct subset of salivary gland lesions. True oncocytic lesions of the salivary gland are entirely composed of oncocytes. These are characterized by the presence of abundant eosinophilic granules due to the presence of abundant cytoplasmic mitochondria. Oncocytic lesions of the salivary gland include oncocytosis, oncocytoma, and oncocytic carcinoma. In addition to the true oncocytic lesion, there exists another group of salivary gland lesions, which demonstrate cells with abundant and occasionally granular cytoplasm. These are often termed as "oncocytoid" lesions. The recently proposed Milan System for reporting salivary gland cytology clearly states that fine-needle aspiration specimens representing oncocytic/oncocytoid lesions of salivary gland cannot effectively distinguish between a nonneoplastic lesion, benign and malignant neoplasms. Therefore, most lesions lacking classic cytomorphologic features will be classified under the umbrella diagnostic term of "Salivary Gland Neoplasm of Uncertain Malignant Potential" (SUMP). In this review, we discuss and illustrate key clinicopathologic and radiologic features that can help the practicing cytopathologist narrow down the differential and provide the best management based diagnosis.

The Role of Ancillary Techniques in Salivary Gland Cytopathology Specimens

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

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.

Comparison of p63/p40 Expression With Myoepithelial Markers in Minor Salivary Gland Tumors

The present study aimed to compare the expression of p63/p40 with smooth muscle actin (SMA) and vimentin (VIM) by myoepithelial cells in minor salivary gland tumors. Fifty-two formalin-fixed paraffin-embedded samples of minor salivary gland tumors derived from intercalated duct (pleomorphic adenoma [PA], adenoid cystic carcinoma [ACC], epithelial-myoepithelial carcinoma [EMC], polymorphous adenocarcinoma [PAC], and secretory carcinoma [SC]) and 3 samples of minor salivary gland tumors derived from excretory duct (mucoepidermoid carcinoma [MEC]) were evaluated by means of immunohistochemistry. The data were analyzed qualitatively. The results indicated that p63 and p40 expression were detected in myoepithelial cells present in PA, ACC, and EMC. However, both proteins were also observed in squamous areas of PA and all cases of MEC. SMA were noticed in some myoepithelial cells of PA, ACC, and EMC. Expression of SMA was negative in the other salivary gland tumors evaluated. VIM was constantly expressed by myoepithelial cells in PA, ACC, and EMC. VIM was also observed in cells of PAC and SC, but not in squamous areas of PA and MEC. In conclusion, p63 expression is almost comparable with VIM in detecting myoepithelial cells, an immunolabeling pattern not followed by p40, and consequently, caution has to be taken during the interpretation of salivary gland tumor exhibiting an p63/p40 phenotype in order to avoid a misdiagnosis.

The screening and electron microscopy observation of mammary analogue secretory carcinoma in Chinese

Mammary analogue secretory carcinoma of salivary gland (MASC) is a tumor with histopathologic and immunophenotypic features mimicking secretory carcinoma of the breast harboring the ETV6 split. The expression of mammaglobin, S-100, Ki-67, P63 and ETV6 split were detected in twelve cases of acinar cell carcinoma and fourteen cases of mammary analogue secretory carcinoma of salivary gland by immunohistochemistry and fluorescence in situ hybridization respectively. The expression of ETV6 gene split was detected in fourteen mammary analogue secretory carcinomas of salivary gland with positive expression of mammaglobin. Eight of mammary analogue secretory carcinomas of salivary gland also tested positive for the ETV6 gene split via fluorescence in-situ hybridization (FISH). The concordance rate of the immunohistochemistry and FISH was 72.3%. Mammaglobin and ETV6 gene split detection could help to distinguish mammary analogue secretory carcinoma of salivary gland. The mammary analogue secretory carcinoma of salivary gland specimens were also examined under transmission electron microscope. And apical junctional complexes were observed in the loosely connected tumor cells.

Clinicopathological characteristics and outcome of 31 patients with ETV6-NTRK3 fusion gene confirmed (mammary analogue) secretory carcinoma of salivary glands

OBJECTIVES

In 2010, a new subtype of salivary gland cancer (SGC), (mammary analogue) secretory carcinoma (SC), was defined, characterized by the ETV6-NTRK3 fusion gene. As clinical behavior and outcome data of this histological subtype tumor are still sparse, we aimed to describe the clinicopathological course and outcome of a series of translocation positive SC patients.

PATIENT AND METHODS

We re-evaluated the pathological diagnosis of a subset of SGCs, diagnosed in 4 of 8 Dutch head and neck centers. Subsequently, tumors with a morphological resemblance to SC were tested for the ETV6-NTRK3 fusion gene using RT-PCR. Furthermore, patients prospectively diagnosed with SC were included. The clinical characteristics and outcomes were retrieved from the patient files.

RESULTS

Thirty-one patients with ETV6-NTRK3 fusion gene positive SC were included. The median age was 49 years, 17 patients (55%) were male. Eighteen tumors (58%) arose in the parotid gland. One patient presented with lymph node metastasis. All patients underwent tumor resection and 4 patients had a neck dissection. Four patients had re-resection and 15 patients (48%) received postoperative radiotherapy. One patient developed a local recurrence, no regional recurrences or distant metastases were observed. After a median follow-up of 49 months the 5- and 10-year overall survival were 95%, the 5- and 10-year disease free survival were 89%.

CONCLUSION

The clinical course of SC is favorable with a low rate of locoregional recurrence and excellent survival. Given the low incidence of nodal metastases, elective neck treatment, i.e. surgery and/or radiotherapy, does not seem to be indicated.

Primary mammary analogue secretory carcinoma of the lung: a case report

Mammary analogue secretory carcinoma (MASC) is a recently discovered salivary gland tumor described mostly in the major salivary glands and occasionally in the skin. We report a primary endobronchial tumor with histology, immunophenotype, and ETV6 rearrangement characteristic of MASC in a 62-year-old woman. The diagnosis was initially made on a transbronchial biopsy with fluorescence in situ hybridization confirmation of ETV6 rearrangement. The patient underwent lobectomy demonstrating a large endobronchial mass. To our knowledge, this is the first report of MASC arising as a primary pulmonary tumor. This tumor was unusual in that it is the largest (8.5 cm) MASC ever reported, showed an increased mitotic count (6/10 high-power fields) without high-grade cytology, and presented with advanced-stage disease that included visceral pleural invasion and lymph node metastasis.

A systematic review including an additional pediatric case report: Pediatric cases of mammary analogue secretory carcinoma

IMPORTANCE

Mammary Analogue Secretory Carcinoma (MASC) is a newly characterized salivary gland carcinoma resembling secretory carcinoma of the breast. Prior to being described, MASC was most commonly misdiagnosed as Acinic Cell Carcinoma. Though MASC is predominantly an adult neoplasm, cases have been reported in the pediatric population. Reporting and summarizing of known cases is imperative to understand the prognosis and clinical behavior of MASC.

OBJECTIVE

EVIDENCE REVIEW: Web of Science, Medline, EMBASE, and The Cochrane Library were searched for studies that included pediatric cases of MASC. Data on clinical presentation, diagnosis and management, and pathology were collected from all pediatric cases.

FINDINGS

CONCLUSIONS AND RELEVANCE: Since the first case of MASC in the pediatric population was described in 2011, only 12 cases, including this one, have been described in the literature. With this paucity of information, much remains unknown regarding this new pathologic diagnosis. The collection of clinical outcomes data of children with MASC is needed to better understand the behavior of this malignancy as well as determine optimal treatment regimens.

Clinicopathologic and molecular characterization of mammary analogue secretory carcinoma of salivary gland origin

BACKGROUND

Mammary analogue secretory carcinoma (MASC) is a newly recognized salivary gland tumor that harbors a characteristic balanced chromosomal translocation t (12; 15) (p13; q25) resulting in an ETV6-NTRK3 fusion gene.

METHODS

Retrospective study of 111 salivary gland carcinomas revealed 37 cases with secretory features and growth patterns resembling secretory carcinoma of breast. These 37 cases were originally diagnosed as acinic cell carcinoma, adenocarcinoma not otherwise specified and cystadenocarcinoma. Positive immunostaining for S-100 protein and mammaglobin, followed by detection of ETV6 gene rearrangement by FISH and/or ETV6-NTRK3 fusion transcript by RT-PCR were used to identify MASCs.

RESULTS

In the cohort of 37 salivary carcinomas with secretory features we have identified 10 cases of MASC. All 10 MASCs were positive for mammaglobin, S-100 protein and SOX10, while staining for DOG1 and p63 protein were mostly absent. In 7/10 cases, both FISH and RT-PCR were positive while three remaining cases showed break of ETV6 gene by FISH analysis and the RT-PCR was negative. Clinical follow-up data were obtained in 6 out of 10 patients with MASC. In 3 patients cervical lymph node metastases developed, one patient with high grade transformed MASC died with multiple distant bone metastases, and local recurrence was observed in three patients.

CONCLUSION

Our clinicopathological data are in keeping with previous studies; in most cases, MASC is a low-grade malignancy with overall favorable prognosis. In rare cases, however, MASC with high-grade transformation may behave aggressively, and these patients could benefit from targeted biological treatment using tyrosine kinase inhibitors.

Combined DOG1 and Mammaglobin Immunohistochemistry Is Comparable to ETV6-breakapart Analysis for Differentiating Between Papillary Cystic Variants of Acinic Cell Carcinoma and Mammary Analogue Secretory Carcinoma

BACKGROUND

We investigated the reliability of combined DOG1 and mammaglobin immunohistochemistry compared with ETV6 fluorescence in situ hybridization (FISH) in the assessment of salivary tumors previously diagnosed as acinic cell carcinoma (ACC). Ultrastructural features of cases reclassified as mammary analogue secretory carcinoma (MASC) were assessed by transmission electron microscopy (TEM).

METHODS

Immunohistochemical (IHC) reactivity to DOG1 and mammaglobin was validated against FISH targeting the ETV6 gene in all 14 cases.

RESULTS

Three cases with papillary cystic histomorphology previously diagnosed as ACC were revised to MASC. TEM features of the ETV6 rearrangement-positive MASC cases showed large numbers of secretory granules with extrusion into the intercellular spaces, well-developed endoplasmic reticulum, lipid-laden vacuoles, well-formed microvilli, and large lining cystic spaces.

CONCLUSIONS

Combined DOG1 and mammaglobin immunohistochemistry is comparable to ETV6 -breakapart analysis for differentiating between papillary cystic variants of ACC and MASC.

New Developments in Salivary Gland Pathology: Clinically Useful Ancillary Testing and New Potentially Targetable Molecular Alterations

Accurate diagnosis of salivary gland tumors can be challenging because of the many diagnostic entities, the sometimes extensive morphologic overlap, and the rarity of most tumor types. Ancillary testing is beginning to ameliorate some of these challenges through access to newer immunohistochemical stains and fluorescence in situ hybridization probes, which can limit differential diagnostic considerations in some cases. These ancillary testing strategies are especially useful in small biopsy samples, including aspiration cytology. Molecular techniques are also expanding our understanding of salivary gland tumor pathology and are helping to identify potential targets that may improve treatment for some of these tumors. Here, we summarize the clinical use of new immunohistochemical markers in our practice and review the current understanding of chromosomal rearrangements in salivary gland tumor pathology, emphasizing the prospects for exploiting molecular alterations in salivary gland tumors for diagnosis and targeted therapy. We find that immunohistochemistry and fluorescence in situ hybridization are powerful tools toward the diagnosis of salivary gland tumors, especially when used in a systematic manner based on morphologic differential-diagnostic considerations. As new targeted therapies emerge, it will become increasingly vital to incorporate appropriate molecular testing into the pathologic evaluation of salivary gland cancers.

Mammary Analogue Secretory Carcinoma

Mammary analogue secretory carcinoma (MASC) is a recently described salivary gland tumor that shares the same histologic appearance and ETV6 gene (12p13) rearrangement as secretory carcinoma of the breast. Prior to its recognition, MASC cases were commonly labeled acinic cell carcinoma and adenocarcinoma, not otherwise specified. Despite distinctive histologic features, MASC may be difficult to distinguish from other salivary gland tumors, in particular zymogen-poor acinic cell carcinoma and low-grade salivary duct carcinoma. Although characteristic morphologic and immunohistochemical features form the basis of a diagnosis of MASC, the presence of an ETV6-NTRK3 gene fusion is confirmatory. Given its recent recognition the true prognostic import of MASC is not yet clearly defined.

Ultrastructural Characterization of Mammary Analogue Secretory Carcinoma of the Salivary Glands: A Distinct Entity from Acinic Cell Carcinoma?

Mammary analogue secretory carcinoma (MASC) of the salivary glands is a recently described neoplasm of the salivary glands with a characteristic morphology complemented by a specific cytogenetic translocation and gene rearrangements. Although immunophenotypic and cytogenetic differences allow for a more reliable distinction, ultrastructural features can also provide important information about the relationship between MASC, classic acinic cell carcinoma (AciCC), and AciCC intercalated duct cell-predominant variant. Following approval from the hospital's institutional review board, 7 cases of MASC, 8 cases of classic AciCC, and 4 cases of AciCC intercalated duct cell-predominant variant were retrieved from the pathology files of Massachusetts General Hospital from 2012 to 2015. Electron microscopy was performed using formalin-fixed, paraffin-embedded tissue. Ultrastructural features of all 19 neoplasms of the salivary glands were recorded. The predominant cell-types observed in MASC are those with intercalated/striated duct cell differentiation. These features include prominent invaginations of the cell surface studded with microvilli, and some intra- and intercellular lumina also with a microvillous surface. Classic AciCC dominant cell-type recapitulates acinar cell differentiation. These cells contain large intracytoplasmic zymogen-like granules. AciCC intercalated duct cell-predominant variant showed both cell populations in various proportions with the intercalated/striated duct cell type usually being the dominant one. MASC presents with distinctive ultrastructural features that allows its proper differentiation from classic AciCC. However, significant ultrastructural features overlaps between both AciCC intercalated duct cells-predominant and classic AciCC and MASC. These findings indicate a very close proximity between these tumors.

Newly described salivary gland tumors

This review concentrates on three salivary gland tumors that have been accepted in the recent literature as new neoplastic entities: mammary analog secretory carcinoma (MASC), sclerosing polycystic adenoma (SPA) and cribriform adenocarcinoma of tongue and other minor salivary glands (CAMSGs). MASC is a distinctive low-grade malignant salivary cancer that harbors a characteristic chromosomal translocation, t(12;15) (p13;q25) resulting in an ETV6-NTRK3 fusion. SPA is a rare lesion often mistaken histologically for low-grade salivary carcinoma. Previously thought to be a reactive fibroinflammatory process, but recent evidence of clonality, recurrences in up 30%, and dysplastic foci suggest it may be truly neoplastic. CAMSG is a distinct tumor entity that differs from polymorphous low-grade adenocarcinoma (PLGA) by location (ie, most often arising on the tongue), by prominent nuclear clearing, alterations of the PRKD gene family and clinical behavior with frequent metastases at the time of presentation of the primary tumor. Early metastatic disease seen in most cases of CAMSG associated with indolent behavior makes it a unique neoplasm among all low-grade salivary gland tumors. Salivary glands may give rise to a wide spectrum of different tumors. They are often diagnostically challenging as morphological features often overlap between different entities. Although conventional morphology in combination with immunohistochemical findings still provide the most important clues for diagnosis, recent advances in molecular pathology offer new diagnostic tools in investigating the differential diagnosis, as well as providing potentially valuable prognostic indicators. In the last two decades, several new salivary gland tumor entities have been described, namely MASC, SPA and CAMSGs.

A New Hitherto Unreported Histopathologic Manifestation of Mammary Analogue Secretory Carcinoma: "Masked MASC" Associated With Low-grade Mucinous Adenocarcinoma and Low-grade In Situ Carcinoma Components

We present a salivary gland tumor of the parotid gland in a 54-year-old woman, which contained a minor mammary analogue secretory carcinoma (MASC) component (20%) intermixed with a morphologically entirely different mucinous adenocarcinomatous component that comprised 80% of the tumor mass and a morphologically nondescript low-grade intraductal carcinoma (in situ) component. On fluorescence in situ hybridization, a break in the ETV6 gene was documented in the mucinous adenocarcinomatous, the conventional MASC, and the intraductal (in situ) components. RT-PCR failed to reveal an ETV6-NTRK3 fusion. The entire conventional MASC and only rare mucinous adenocarcinoma tumor cells were mammaglobin positive, whereas the low-grade intraductal carcinoma (in-situ) component was negative. S-100 protein stained only the MASC component.

The unique luminal staining pattern of cytokeratin 5/6 in adenoid cystic carcinoma of the breast may aid in differentiating it from its mimickers

Adenoid cystic carcinoma (AdCC) of the breast is an uncommon but distinct neoplasm composed of a dual cell population polarized around true glandular (luminal) spaces and pseudolumina. The aim of this study was to clarify whether various immunohistochemical markers (CK7, EMA, CD117, p63, calponin, CD10, S100, CK5/6, CK14, vimentin, and type IV collagen) can distinguish between the two cell types in classical AdCC (n = 14) and in collagenous spherulosis (n = 5). The sensitivity and specificity of these 11 markers to distinguish luminal from abluminal cells were evaluated using a curve created by plotting the true-positive rate (sensitivity) against the false-positive rate (1 - specificity) at threshold settings of 0, 10, 50, and 70 %. The most sensitive and specific markers for luminal cells in AdCC were CK7 and EMA; those for abluminal cells were type IV collagen, p63, and vimentin. CD10 and S100 did not act as abluminal markers in AdCC. CK5/6, one of the basal/myoepithelial markers, was expressed more frequently in luminal than in abluminal cells of AdCC. Thus, CK5/6 immunostaining resulted in a reverse expression pattern, analogous to what we recently documented in clear cells in mammary adenomyoepithelioma. In conclusion, compared with myoepithelial/abluminal cells of normal breast or collagenous spherulosis, the neoplastic abluminal cells of classical AdCC are characterized by enhanced vimentin and attenuated CD10 and S100. Furthermore, the luminal cells of AdCC show a unique aberrant staining pattern for CK5/6 that may aid in the differential diagnosis.

Mammary analogue secretory carcinoma of parotid: Is preoperative cytological diagnosis possible?

Mammary analogue secretory carcinoma is a recently recognized tumor of salivary gland with characteristic t(12;15)(q13;q25) that results in ETV6-NTRK3 fusion product. Distinguishing mammary analogue secretory carcinoma from other salivary gland tumors is important. Present study highlights cytologic findings in three cases of mammary analogue secretory carcinoma of parotid which facilitate preoperative diagnosis with the aid of ancillary diagnostic techniques. Fine needle aspiration cytology of parotid was performed on three cases after clinical examination. Immunocytochemistry for mammoglobin and S100 were performed. Parotidectomy was done in all cases. The corresponding hematoxylin and eosin stained slides and blocks of all cases were studied. Molecular analysis was done in one of the cases. Cases 1 and 3 revealed uniform atypical epithelial cells arranged in branching papillary pattern with few cells in microcystic pattern. Case 2 showed atypical cells arranged mainly in loose clusters and few singly dissociated. Individual cells revealed round nuclei, vesicular chromatin, prominent nucleoli and abundant finely vacuolated cytoplasm with metachromasia prominent in May-Grunwald-Giemsa smear (case 3). Characteristic hob-nail cells covering papillae were observed in cases 1 and 3. Immunocytochemistry showed strong positivity for mammoglobin and S100 thereby confirming the diagnosis of mammary analogue secretory carcinoma preoperatively. The diagnosis was in concordance with surgical specimen. Also, characteristic ETV6-NTRK3 translocation was confirmed in case 1. Increased awareness and high index of suspicion is necessary for the upfront diagnosis, more so for the papillary variant of mammary analogue secretory carcinoma. Immunocytochemistry aids in confirming this preoperative diagnosis, based on which treatment can be planned. Diagn. Cytopathol. 2016;44:519-525. © 2016 Wiley Periodicals, Inc.

Mammary Analogue Secretory Carcinoma of Salivary Glands: Molecular Analysis of 25 ETV6 Gene Rearranged Tumors With Lack of Detection of Classical ETV6-NTRK3 Fusion Transcript by Standard RT-PCR: Report of 4 Cases Harboring ETV6-X Gene Fusion

ETV6 gene abnormalities are well described in tumor pathology. Many fusion partners of ETV6 have been reported in a variety of epithelial and hematological malignancies. In salivary gland tumor pathology, however, the ETV6-NTRK3 translocation is specific for mammary analogue secretory carcinoma (MASC), and has not been documented in any other salivary tumor type. The present study comprised a clinical and molecular analysis of 25 cases morphologically and immunohistochemically typical of MASC. They all also displayed the ETV6 rearrangement as visualized by fluorescent in situ hybridization but lacked the classical ETV6-NTRK3 fusion transcript by standard reverse-transcriptase-polymerase chain reaction. In 4 cases, the classical fusion transcript was found by more sensitive, nested reverse-transcription-polymerase chain reaction. Five other cases harbored atypical fusion transcripts as detected by both standard and nested reverse-transcription-polymerase chain reaction. In addition, fluorescent in situ hybridization with an NTRK3 break-apart probe was also performed; rearrangement of NTRK3 gene was detected in 16 of 25 cases. In 3 other cases, the tissue was not analyzable, and in 2 further cases analysis could not be performed because of a lack of appropriate tissue material. Finally, in the 4 remaining cases whose profile was NTRK3 split-negative and ETV6 split-positive, unknown (non-NTRK) genes appeared to fuse with ETV6 (ETV6-X fusion). In looking for possible fusion partners, analysis of rearrangement of other kinase genes known to fuse with ETV6 was also performed, but without positive results. Although numbers were small, correlating the clinico-pathologic features of the 4 ETV6-X fusion tumors and 5 MASC cases with atypical fusion transcripts raises the possibility of that they may behave more aggressively.