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.

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.

Imaging identification of primary mammary analogue secretory carcinoma and acinic cell carcinoma in major salivary glands

OBJECTIVE

The present study aimed to characterize and differentiate the ultrasonography (US) and computed tomography (CT) features of mammary analogue secretory carcinoma (MASC) and acinic cell carcinoma (AciCC).

METHODS AND PATIENTS

A total of 83 patients with clinically proven MASC and AciCC were analyzed. The following characteristics were assessed on US, CT, and magnetic resonance imaging: lesion size, shape, margin, echogenicity, echotexture, cystic components, posterior echo, vascularity, density, degree of enhancement, enhancement pattern, signal intensity (SI) on T1- and T2-weighted images (WI), hemorrhages, and lymph node enlargement.

RESULTS

Similarities were observed between the imaging performance of MASC and AciCC. Differences between the two characteristics of shape on US and cystic components on CT were statistically significant. The proportion of MASC to regular shape on US (p = 0.006) and cystic components on CT (p = 0.027) was significantly higher than that of AciCC. Regular shape on US had the highest sensitivity in the identification of MASC and AciCC, while regular shape on US + cystic component on CT had the highest specificity.

CONCLUSIONS

The shape on US and cystic components on CT are key characteristics for distinguishing MASC and AciCC.

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 case of metachronous bilateral secretory carcinoma

Secretory carcinoma (SC) was first recognized as a distinct salivary malignancy in 2010. In the nine years since its recognition, there have been multiple reports of SC of the major and minor salivary glands, as well one case of tongue base involvement. Here we present the first reported case of bilateral SC. The first tumor, diagnosed before the recognition of SC, was classified as mucoepidermoid carcinoma. After the contralateral parotid tumor was diagnosed as SC in 2016, the two histologies were compared, and the mucoepidermoid carcinoma was reclassified as SC. In this report, we describe our patient’s clinical course and review the SC literature, with a focus on pathologic diagnosis and clinical prognosis.

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.

Atypical Presentation of Mammary Analogue Secretory Carcinoma of the Lip

Mammary analogue secretory carcinoma (MASC) of the salivary gland is a rare tumor that was first described by Skalova et al in 2010, and since then, only a few hundred cases have been reported in the literature. Prior to Skalova's report, MASC was histologically misclassified as acinic cell carcinoma (ACC), pleomorphic adenoma, mucoepidermoid carcinoma, or adenocarcinoma, not otherwise specified. Mammary analogue secretory carcinoma has a low incidence rate overall, accounting for less than 0.3% of all salivary gland tumors. Histopathologic and cytogenic analysis of MASC is identical to secretory carcinoma of the breast, leading to the proposed name by Skalova. The purpose of this case presentation is to describe an atypical presentation of MASC, to compare this case with the classic description of MASC, and to contrast the various features of MASC to ACC in order to improve the accuracy of future diagnoses and help guide treatment.

A case of mammary analogue secretory carcinoma of the parotid gland: A case report

RATIONALE

Mammary analogue secretory carcinoma is a low grade salivary gland malignancy, first described by Skalova et al in 2010. The histological, immunohistochemical, and molecular characteristics of this tumor resemble those of secretory carcinoma of the breast.

PATIENT CONCERNS

A 40-year-old male patient without any specific past history came with complaints of 4 cm-sized hard, fixed, right infra-auricular mass without tenderness. There was no enlarged or enhancing lymph node in both neck.

DIAGNOSES

Fine needle aspiration biopsy was done for right parotid mass and pathologic report was "lymphocytes only" that suggested benign or low-grade malignant parotid tumor.

INTERVENTIONS

Partial parotidectomy including mass excision was performed. Operative finding showed hard bluish mass located in deep lobe of right parotid gland.

OUTCOMES

Final pathologic report revealed secretory carcinoma of parotid gland. Homogenous eosinophilic secretions were identified inside microcystic structure. The immunophenotype was positive for epithelial membrane antigen, vimentin, S-100 protein. After 15 months of the surgery, the patient showed negative evidence of disease state.

LESSONS

We present here a case of mammary analogue secretory carcinoma of the parotid gland to help further characterize this rare tumor.

Mammary Analogue Secretory Carcinoma of the Thyroid Mimicking Locally Advanced Papillary Thyroid Carcinoma: A Rare Case Report

Mammary analogue secretory carcinoma (MASC) harboring ETV6 gene rearrangements was first described in the salivary gland with a relatively favorable prognosis and a possible molecular therapeutic target with pan-Trk inhibitors. Recently, primary MASC of the thyroid gland has been reported. We report a case of a 4.0 cm MASC arising from the left thyroid of a 58-year-old female with extrathyroidal extension. Initially, it was diagnosed by fine needle aspiration as suspicious for papillary thyroid carcinoma (PTC) and subsequently called a poorly differentiated carcinoma on resection. A final diagnosis of primary MASC of the thyroid was confirmed after an expanded immunohistochemical panel and identification of an ETV6 gene rearrangement by fluorescence in situ hybridization. Morphologically, the tumor was composed of solid, microcystic and focally papillary growth with dense fibrotic stroma and necrosis. Overlapping cytological features with PTC were identified, including foci of enlarged cells with irregular nuclear membranes/grooves. However, most of the cells contained prominent nucleoli with intraluminal and intracytoplasmic eosinophilic secretions. Immunohistochemically, the tumor cells were strongly positive for pancytokeratin, cytokeratin 7, PAX8, mammaglobin, and GCDFP-15, with rare staining for GATA3 and S100 and negative for TTF-1 and thyroglobulin. We report a rare case of a primary thyroid MASC, initially misdiagnosed as PTC. Pathologists should be aware of this entity and, given the similarities to PTC, have a high index of suspicion, prompting the addition of immunohistochemical and molecular studies. Furthermore, an accurate diagnosis is important because of the possible prognostic and treatment implications.

Mammary analogue secretory carcinoma of salivary glands: diagnostic pitfall with distinct immunohistochemical profile and molecular features

Mammary analogue secretory carcinoma (MASC) is a newly defined entity among salivary gland malignancies which has just been established in the 4^th edition of the WHO classification of head and neck tumors. MASC (synonym: secretory carcinoma) are characterized by a specific rearangement of the ETV6 gene locus. Here, we present a series of 3 MASC cases including clinical data with follow-up for up to 26 months. All tumours immunhistochemically displayed strong positivity for cytokeratin 7, and mammaglobin, focal positivity for S100, cytokeratin 5/6 and muc-4. In contrast, immunhistochemical stainings against cytokeratin 14, hormon receptors, Her2/neu, androgen receptor and prostate-specific antigen were consistently negative. FISH analysis showed translocation of the ETV6 gene locus in the majority of tumour cell nuclei. During clinical follow-up, no local relapse or metastasis was detected. As these carcinomas are clinically and radiologically indistinguishable from other salivary gland tumours and as therapeutic approaches and prognosis might differ, we need to be able to diagnose MASC correctly.

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.

Secretory carcinoma - impact of translocation and gene fusions on salivary gland tumor

Secretory carcinoma (SC), previously described as mammary analogue secretory carcinoma (MASC), is a recently described salivary gland tumor which morphologically resembles mammary secretory carcinoma. The first description of SC/MASC, reported by Skálová et al. in 2010, was as a rare salivary carcinoma imitating secretory carcinoma of the breast. SC/MASC is a unique salivary gland tumor with morphological overlap with acinic cell carcinoma (AciCC), mucoepidermoid carcinoma (MEC), and adenocarcinoma not otherwise specified (ADC-NOS). SC/MASC shares similar clinicopathological features with AciCC. As a critical difference between SC/MASC and AciCC, SC/MASC characteristically has the chromosomal translocation t(12;15)(p13;q25) which leads to a fusion gene between the ETV6 gene on chromosome 12 and the NTRK3 gene on chromosome 15. This genetic background is an important differential diagnostic finding for excluding other salivary gland tumors and may be a critical factor determining the prognosis for patients with SC/MASC. Research in recent years has provided a large body of new data on SC/MASC and suggests the possibility that the ETV6-NTRK3 translocation could be a therapeutic target. Here, we review the morphological and clinicopathological features of SC/MASC and discuss new directions for therapy.

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.

Genetic alterations in salivary gland cancers

Salivary gland cancers are an incredibly heterogeneous group of tumors that include 24 histologically distinct tumor types. The use of new genetic methods has paved the way for promising advancements in our understanding of the molecular biology underlying each type of tumor. The objective of this review was to highlight common oncogenes, tumor suppressor genes, and cytogenetic and epigenetic changes associated with the most common tumor types: mucoepidermoid carcinoma, adenoid cystic carcinoma, salivary duct carcinoma, mammary analogue secretory carcinoma, hyalinizing clear cell carcinoma, carcinoma ex pleomorphic adenoma, and acinic cell carcinoma. Recent insights into the pathogenesis of each cancer subtype have helped better define and classify these tumors. Further research in salivary gland cancers should focus on determining the key genes involved in the tumorigenesis of each distinct malignancy and identifying individualized chemotherapies directed at these targets. Cancer 2016;122:1822-31. © 2016 American Cancer Society.

What hides behind the MASC: clinical response and acquired resistance to entrectinib after ETV6-NTRK3 identification in a mammary analogue secretory carcinoma (MASC)

Here, we describe the dramatic response of a patient with an ETV6-NTRK3-driven mammary analogue secretory carcinoma to treatment with a pan-Trk inhibitor, and the development of acquired resistance linked to a novel NTRK3 mutation that interferes with drug binding. This case emphasizes how molecular profiling can identify therapies for rare diseases and dissect mechanisms of drug resistance.

Background

Mammary analogue secretory carcinoma (MASC) is a recently described pathologic entity. We report the case of a patient with an initial diagnosis of salivary acinic cell carcinoma later reclassified as MASC after next-generation sequencing revealed an ETV6-NTRK3 fusion.

Patients and methods

This alteration was targeted with the pan-Trk inhibitor entrectinib (Ignyta), which possesses potent in vitro activity against cell lines containing various NTRK1/2/3 fusions.

Results

A dramatic and durable response was achieved with entrectinib in this patient, followed by acquired resistance that correlated with the appearance of a novel NTRK3 G623R mutation. Structural modeling predicts that this alteration sterically interferes with drug binding, correlating to decreased sensitivity to drug inhibition observed in cell-based assays.

Conclusions

This first report of clinical activity with TrkC inhibition and the development of acquired resistance in an NTRK3-rearranged cancer emphasize the utility of comprehensive molecular profiling and targeted therapy for rare malignancies (NCT02097810).

Mammary analogue secretory carcinoma of salivary glands: a new entity associated with ETV6 gene rearrangement

Mammary analogue secretory carcinoma (MASC) is a recently described salivary gland tumour that harbours the recurrent ETV6-NTRK3 translocation. This is the first series of MASC cases identified in the historic cohort of carcinomas of salivary glands with clinical/pathological correlation and follow-up data. We reviewed 183 primary carcinomas of major and minor salivary glands resected at the Medical University of Gdańsk, Poland, between 1992 and 2012. Based on morphology and immunohistochemistry, cases suspicious for MASC were selected, and the diagnosis was confirmed by fluorescence in situ hybridization (FISH) for ETV6 rearrangement and by RT-PCR for the ETV6-NTRK3 fusion transcript. Seven carcinomas met the criteria of MASC, as they exhibited a typical appearance with solid/microcystic and papillary architecture and intraluminal secretions, and cells completely devoid of basophilic cytoplasmic zymogen granules indicative of true acinar differentiation. The only paediatric case was an unencapsulated tumour composed of macrocystic structures covered by a mostly single but, focally, double layer of cells with apocrine morphology. In all cases, the neoplastic cells revealed immunoreactivity for S100, mammaglobin, cytokeratin CK7, CK8, STAT5a and vimentin. FISH for ETV6 gene rearrangement was positive in six out of seven cases, and RT-PCR was positive in three cases. MASC is a new entity of malignant epithelial salivary gland tumours not included in the 2005 WHO Classification of Head and Neck Tumours. There is a growing body of evidence that it is not as rare as was assumed, as is also indicated by our series (3.8 %). In most cases, MASC shares some microscopic features with AciCC, adenocarcinoma/cystadenocarcinoma NOS and low-grade MEC. In rare cases, MASC with high-grade transformation may mimic the morphological appearances of high-grade salivary gland malignancies, such as salivary duct carcinoma.

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

The recently described mammary analogue secretory carcinoma (MASC) is a low-grade salivary gland malignancy that harbors the recurrent cytogenetic abnormality t(12;15) (p13;q25) ETV6-NTRK3. Confirmation of this is currently considered the gold standard for diagnosis. Some have postulated that morphology together with supporting immunohistochemistry is sufficient to diagnose MASC. In this study we retrospectively review a series of 19 MASCs diagnosed based on histology in conjunction with immunohistochemistry; subsequently we performed in situ hybridization using an ETV6 break-apart probe. Immunohistochemistry for S100 protein and mammaglobin as well as fluorescence in situ hybridization using the Vysis ETV6 Dual Color Break-Apart FISH Probe Kit were performed on all cases. The 19 cases were from 12 females and 7 males with ages ranging from 16 to 76 years (mean = 45 years). Sixteen cases were from the parotid gland, 1 case was from a periparotid lymph node and 2 cases were from the submandibular gland. All 19 cases demonstrated moderate to strong expression of S100 protein. Eighteen cases demonstrated strong, diffuse expression of mammaglobin, while one case had only rare tumor cells that strongly expressed mammaglobin. Eighteen of 19 cases (95 %) demonstrated the ETV6 rearrangement by fluorescence in situ hybridization. Given that morphology together with immunohistochemistry is highly correlated with the ETV6 gene rearrangement, we conclude that molecular confirmation is not required to diagnose MASC.

Mammary analogue secretory carcinoma mimicking salivary adenoma

Mammary analogue secretory carcinoma (MASC) is a recently described salivary gland tumor characterized by ETV6 translocation. It appears that prior studies have identified MASC by reviewing salivary gland carcinomas, such as acinic cell carcinoma and adenocarcinoma, not otherwise specified. To address the possibility of MASC mimicking benign salivary neoplasms we reviewed 12 salivary gland (cyst)adenomas diagnosed prior to the discovery of MASC. One encapsulated (cyst)adenoma of the parotid gland demonstrated features of MASC. The diagnosis was confirmed by fluorescence in situ hybridization with an ETV6 break-apart probe. An unusual complex pattern of ETV6 rearrangement with duplication of the telomeric/distal ETV6 probe was identified. This case illustrates that MASC may mimic salivary (cyst)adenomas. To more accurately assess true clinical and morphologic spectrum of MASC, future studies may have to include review of salivary (cyst)adenomas. The differential diagnosis of MASC may have to be expanded to include cases resembling salivary (cyst)adenomas.

Mammary analogue secretory carcinoma of salivary glands is a lipid-rich tumour, and adipophilin can be valuable in its identification

AIMS

Mammary analogue secretory carcinoma (MASC) of salivary glands shows morphological similarities to milk-secreting mammary epithelial cells. The aim of this study was to analyse the immunohistochemical expression of adipophilin (a component of milk lipid globule membranes) and of proteins related to secretory mechanisms (STAT5a and mammaglobin) in MASC and other salivary tumours.

METHODS AND RESULTS

Ten cases of MASC (all with ETV6 translocation) and 83 other salivary carcinomas were studied. In all MASC cases, adipophilin stained numerous large lipid droplets. These droplets were minute in other salivary carcinomas, except for sebaceous carcinoma. Overexpression of STAT5a was detected in all MASC cases, but only occasionally in other carcinomas. Mammaglobin expression occurred frequently in MASC (70% of cases), whereas, in other carcinomas, it was uncommon and limited. Only MASC showed cytoplasmic reactivity for p63, particularly in papillary-cystic areas. Positivity for S100, vimentin and high molecular weight keratin was observed in 100% of MASC cases.

CONCLUSIONS

MASC is a lipid-rich tumour containing large lipid droplets covered by adipophilin. This finding can be included among its defining immunohistochemical features, and possibly represents lactation-like secretory differentiation. Strong expression of STAT5a and cytoplasmic p63 in MASC reinforces this hypothesis.

Mammary analogue secretory carcinoma of the parotid gland as a secondary malignancy in a childhood survivor of atypical teratoid rhabdoid tumor

We report the first case of mammary analogue secretory carcinoma (MASC) arising as a secondary malignancy in a 14 years old child with a history of atypical teratoid rhabdoid tumor (ATRT). Although MASC and ATRT are both rare malignancies, they do not share the same genetic and molecular profiles. MASC is a salivary malignancy characterized by a t(12;15)(p13;q25) translocation, resulting in an ETV6-NTRK3 fusion product encoding for a tyrosine kinase. ATRT is a highly malignant pediatric tumor characterized by a chromosome 22 mutation in the hSNF5/INI1 gene, encoding for a chromatin remodeling protein. Additionally, although mucoepidermoid carcinoma has been described as a secondary malignancy post-therapy for head and neck tumors, MASC has only been reported as a primary malignancy. Our patient was treated with a complete resection of his left sided ATRT at age 3 followed postoperatively with chemoradiotherapy. At age 14 he underwent a parotidectomy for his 1 year history of a left sided preauricular mass and was subsequently diagnosed with MASC. We not only report a case of two rare malignancies in one patient, but also the first case of MASC arising as a secondary malignancy.

Mammary analogue secretory carcinoma: update on a new diagnosis of salivary gland malignancy

OBJECTIVES/HYPOTHESIS

To review the known histopathologic findings and clinical behavior of mammary analogue secretory carcinoma (MASC).

DATA SOURCES

PubMed.

REVIEW METHODS

Literature search using the terms "Mammary analogue secretory carcinoma," "Mammary analog secretory carcinoma," and "MASC" to identify all relevant publications.

RESULTS

MASC is an unusual and rare malignant salivary gland tumor first described in 2010. It shares histologic, immunohistochemical, and genetic features with secretory carcinoma of the breast. The clinical behavior of MASC ranges from slowly growing tumors that infrequently recur after surgical resection to aggressive tumors that cause widespread metastasis and death. Many cases of MASC were discovered in archived cases previously classified as acinic cell carcinoma, mucoepidermoid carcinoma, and adenocarcinoma not otherwise specified.

CONCLUSION

MASC is a newly recognized variant of salivary gland malignancy. Further research is needed to better delineate its overall prevalence and to define an appropriate treatment algorithm for this new clinical entity.

Mammary analogue secretory carcinoma of salivary gland origin: an update and expanded morphologic and immunohistochemical spectrum of recently described entity

Mammary analogue secretory carcinoma of salivary gland origin (MASC) is a recently described tumor with ETV6 translocation. Akin to secretory breast cancer, MASC expresses S-100 protein, mammaglobin, vimentin, and harbors a t(12;15) (p13;q25) translocation which leads to ETV6-NTRK3 fusion product. Histologically, MASC displays a lobulated growth pattern and is often composed of microcystic, tubular, and solid structures with abundant eosinophilic homogeneous or bubbly secretions. Colloid-like secretory material stains positive for periodic acid-Schiff (PAS) with and without diastase and for Alcian blue. The cells of MASC are devoid of PAS-positive secretory zymogen granules. These features help to exclude the most important differential diagnostic considerations, namely acinic cell carcinoma, low-grade cribriform cystadenocarcinoma, cystadenocarcinoma (not otherwise specified), and low-grade mucoepidermoid carcinoma. To date the presence of the ETV6-NTRK3 fusion gene has not been demonstrated in any other salivary gland tumor than MASC. It is likely that MASC is more common than currently recognized and with further studies, the clinical need for molecular studies of the ETV6-NTRK3 fusion may diminish. However, molecular testing is recommended at this time to arrive at the diagnosis of MASC.

GATA3 immunohistochemical expression in salivary gland neoplasms

GATA3 is a zinc finger transcription factor that regulates the normal development of many tissues and cell types. Recent studies have shown that immunohistochemical nuclear staining for GATA3 among tumors is highly restricted to carcinomas of breast and urothelial origin; however salivary gland tumors have not been tested. Given that breast and salivary gland tissues are very similar with respect to embryologic development and structure, we performed GATA3 staining on a spectrum of salivary gland neoplasms. GATA3 immunohistochemistry was performed on a diverse collection of 180 benign and malignant salivary gland neoplasms including 10 acinic cell carcinomas, 2 adenocarcinomas not otherwise specified, 41 adenoid cystic carcinomas, 2 epithelial-myoepithelial carcinomas, 1 low grade cribriform cystadenocarcinoma, 15 mammary analogue secretory carcinomas, 7 metastatic squamous cell carcinomas, 27 mucoepidermoid carcinomas, 2 oncocytic carcinomas, 5 oncocytomas, 34 pleomorphic adenomas, 4 polymorphous low grade adenocarcinomas, 25 salivary duct carcinomas, and 5 Warthin tumors. Staining for GATA3 was observed in 92/180 (51 %) of salivary gland tumors. GATA3 staining was observed in most of the tumor types, but diffuse immunolabeling was consistently seen in salivary duct carcinoma (25 of 25) and mammary analogue secretory carcinoma (15 of 15)-the two tumor types that most closely resemble breast neoplasia. Background benign salivary gland tissue was also usually weakly positive in both acini and ducts. GATA3 immunostaining is not restricted to tumors of breast and urothelial origin. Rather, it is expressed across many different types of salivary gland neoplasms. As a result, salivary gland origin should be considered in the differential diagnosis of a GATA3-positive carcinoma, particularly in the head and neck. Although GATA3 immunohistochemistry is not helpful in resolving the differential diagnosis between a primary salivary gland neoplasm and metastatic breast cancer, it may have some utility in subtyping salivary gland tumors, particularly salivary duct carcinoma and mammary analogue secretory carcinoma.

Unmasking MASC: bringing to light the unique morphologic, immunohistochemical and genetic features of the newly recognized mammary analogue secretory carcinoma of salivary glands

Mammary analogue secretory carcinoma (MASC) is a recently described salivary gland neoplasm that is characterized by its striking morphologic and molecular similarities to secretory carcinoma of the breast. This review highlights the characteristic clinical, histologic, immunophenotypic, and molecular features of MASC, and draws attention to the differential diagnosis of this increasingly recognized tumor.

P63 expression can be used in differential diagnosis of salivary gland acinic cell and mucoepidermoid carcinomas

Differentiation of salivary gland acinic cell carcinoma from mucoepidermoid carcinoma can be diagnostically challenging as both may have prominent mucin production. P63 is a p53 homologue required for limb and epidermal morphogenesis. It is expressed in basal and myoepithelial cells of normal salivary gland tissues. In this immunohistochemical study, we examined the expression of p63 in salivary gland acinic cell and mucoepidermoid carcinomas (MEC) and its use in differentiating these two entities. A search was performed and appropriate cases were selected from Lifespan Hospital System archives as well as the consult archives of one author (DRG). 31 salivary gland acinic cell carcinomas (ACC) and 24 MEC were examined for p63 expression by immunohistochemistry. The nuclear immunoreactivity was examined by both authors and was graded semi-quantitatively with negative being less than 10 % of cells staining. Positive staining was graded as follows: 10-25 % of tumor cells staining was weakly positive, 26-75 % of tumor cells staining was moderately positive, and 76-100 % of tumor cells staining was strongly positive. Negative nuclear staining of the tumor cells was seen in 30/31 (96 %) of salivary gland ACC while 1/31 (3 %) showed diffuse nuclear staining of the tumor cells. This latter case was later reclassified as mammary analogue secretory carcinoma following confirmatory molecular testing for the ETV6-NTRK3 fusion gene. Strong positive nuclear staining of the tumor cells was seen in 24 (100 %) of salivary gland MEC cases. P63 is an immunohistochemical stain that can potentially aid in differentiating unusual ACC with prominent mucin production from MEC of the salivary gland. According to this study, acinic cell carcinoma is always negative for p63 immunoreactivity while mucoepidermoid carcinoma is always positive.

Aspiration biopsy of mammary analogue secretory carcinoma of accessory parotid gland: another diagnostic dilemma in matrix-containing tumors of the salivary glands

Mammary analogue secretory carcinoma (MASC) is a newly described rare salivary gland tumor, which shares morphologic features with acinic cell carcinoma, low-grade cystadenocarcinoma, and secretory carcinoma of the breast. This is the first reported case of MASC of an accessory parotid gland detected by aspiration biopsy with radiologic and histologic correlation in a 34-year-old patient. Sonographically-guided aspiration biopsy showed cytologic features mimicking those of low-grade mucoepidermoid carcinoma, including sheets of bland epithelial cells, dissociated histiocytoid cells with intracytoplasmic mucinous material, and spindle cells lying in a web-like matrix. Histologic sections showed a circumscribed tumor with microcystic spaces lined by bland uniform epithelial cells and containing secretory material. The tumor cells expressed mammaglobin and BRST-2. The cytologic features, differential diagnosis, and pitfalls are discussed. The pathologic stage was pT1N0. The patient showed no evidence of disease at 1 year follow-up.

Re-evaluating historic cohort of salivary acinic cell carcinoma with new diagnostic tools

Mammary analogue secretory carcinoma (MASC) was recently identified as a distinct salivary gland neoplasm, morphologically resembling intercalated duct cell predominant acinic cell carcinoma (AciCC). To determine how frequently MASC has mimicked an intercalated duct cell predominant AciCC, we reviewed AciCC diagnosed from 1956 to 1975. Nine AciCC consecutively diagnosed in that period were identified. Based on morphologic examination, one case diagnosed as AciCC in a male patient in 1960 was re-classified as MASC [confirmed by fluorescence in situ hybridization (FISH) showing ETV6 translocation]. Another case diagnosed as AciCC of the palate in a female patient in 1975 was re-classified as mucoepidermoid carcinoma (based on the lack of acinar differentiation, presence of mucous cells, and confirmed by FISH showing MAML2 translocation). In this proof-of-principle study, we show that 1 in 9 cases historically designated as AciCC represents a MASC. "Intercalated duct cell predominant AciCC", especially among male patients, most likely represent examples of MASC. For anatomic sites outside of the parotid glands, broader differential diagnoses should be considered before accepting morphologic variants of AciCC as the final diagnosis.