Secretory carcinoma (SC), also known as mammary analogue secretory carcinoma (MASC), is a rare salivary gland neoplasm with distinctive morphology that harbors a diagnostic ETV6 gene rearrangement. MASC was first described as a type of salivary gland neoplasm in 2010 and resembles breast secretory carcinoma. It is often mistaken for other neoplasms. It usually acts as an indolent tumor but can occasionally behave in an aggressive manner. We present a rare case of a patient with an aggressive SC/MASC of maxillary gingivobuccal sulcus with microcystic, solid and papillary patterns that showed ETV6 gene rearrangement by fluorescence in situ hybridization. Next-generation sequencing revealed t(12;15)(p13;q25) ETV6-NTRK3 translocation. Because SC/MASCs harbor the ETV6-NTRK3 translocation, molecular studies and immunostains are crucial to confirm the diagnosis and direct therapy.

UNASSIGNED: Mammary analogue secretory carcinoma (MASC) is a new disease among tumours affecting the salivary glands. It was first reported in 2010, and few cases have been reported worldwide. MASC is often incorrectly diagnosed as salivary gland acinic cell carcinoma. We present here the case of a patient with an asymptomatic parotid tumour who underwent a parotidectomy of the superficial lobe.
UNASSIGNED: A 78-year-old female patient came to the clinic for a tumour of approximately 2.5 × 2.5 cm and a hard, elastic consistency that had grown insidiously in the right preauricular region. Magnetic resonance imaging of the head and neck showed a heterogeneous ovoid lesion located in the lower part of the superficial lobe of the right parotid gland, measuring 29 × 27 × 27 mm. A superficial parotidectomy was performed with the facial nerve identified and preserved. Immunohistochemistry was positive for S100, mammaglobin, periodic acid Schiff (PAS) and GATA-3. Fluorescence in situ hybridisation analysis was subsequently performed and Translocation-ETS-Leukemia Virus (ETV6) gene rearrangement observed. These findings were consistent with diagnosis of a MASC. The patient then required no new interventions or adjuvant therapy. At publication, she was free of disease and continues in clinical follow-up.
UNASSIGNED: MASC is a tumour of the saliva glands that is recently described and rare. There are no studies that describe its biological behaviour or prognosis precisely.

This is a case of a 55-year-old female with past medical history of tobacco smoking, hypertension, and lupus who presented with a left lung nodule, found on computed tomographic scan of the chest during workup for a recently diagnosed squamous cell carcinoma in a cervical lymph node. Resection of the lung nodule showed a 2.3-cm well-defined pale-tan mass, and histologic examination showed a well-circumscribed lesion with papillary, solid, and gland-like architectural patterns, with eosinophilic secretions, areas of comedonecrosis, and increased mitotic activity. Immunohistochemical stains showed the lesion to be positive for cytokeratin 7, S100 protein, and focally positive for mammaglobin. Fluorescence in situ hybridization studies confirmed rearrangement of the ETV6 gene at 12p13.2. To date, our case is the second reported case of a primary mammary-analogue secretory carcinoma arising in the lung, and the first to show evidence of tumor necrosis: an unusual feature in an unusual location.

The present study aimed to investigate the histopathological and immunohistochemical characteristics of Mammary Analogue Secretory Carcinoma (MASC) of the Salivary Gland.
METHODS: Four cases of MASC were diagnosed after microscope images review, immunohistochemsitry (IHC) for Mammaglobin protein, Gata3 protein, S-100 protein, DOG1 protein, and break-apart ETV6 fluorescence in situ hybridization (FISH) in forty salivary gland tumors.
RESULTS: We have shown a t(12;15)(p13;q25) ETV6-NTRK3 translocation in all but one case of MASC suitable for analysis. This translocation was not found in any other salivary gland tumor types including acinic cell carcinoma (AciCC, 30 cases) and mucoepidermoid carcinoma (MEC, 6 cases). In IHC, all MASC showed diffuse positivity for Mammaglobin protein, Gata3 protein and S100 protein, as the DOG1 was negative.
CONCLUSIONS: MASC is rare tumor and often misdiagnosed as other salivary tumors, but whose specific histopathological, IHC and molecular genetic characteristics can help to identify it. ETV6-NTRK3 gene translocation is easily found in MASC, but may not occur in every case.

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

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.
CONCLUSIONS: 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.

Mammary analogue secretory carcinoma (MASC) is a recently identified salivary gland neoplasm that can mimic other salivary gland tumours such as acinic cell carcinoma and cystadenocarcinoma. It is distinguished from these by differences in immunohistochemical profile and the identification of an ETV6-NTRK3 translocation (12;15)(p13;q25), which is also found in secretory carcinomas of the breast. Previous publications have suggested that MASC tumours have similar biological behaviour to acinic cell carcinoma. We report two cases of MASC that affected the upper lip, and showed an infiltrative and locally aggressive growth pattern that required several operations to ensure clearance of microscopic tumour cells.

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.

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