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

Abstract

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.

A Case of Primary Mammary Analog Secretory Carcinoma (MASC) of the Thyroid Masquerading as Papillary Thyroid Carcinoma: Potentially More than a One Off

“…Our patient's tumor behaved aggressively, a highly unusual course for salivary MASC which exhibits overall low local recurrence and distant metastsis rates [2]. Thus compared to our patient's tumor, the majority of MASC arising in the salivary glands behave as low grade carcinomas.…”

“…Other than one possible prior case, it has not been reported as arising in the thyroid. MASC of the salivary glands is rare and represents approximately 4 % of primary salivary gland carcinomas [2]. The tumor may be mistaken for numerous other salivary gland tumors including benign tumors such as pleomorphic and monomorphic adenomas and carcinomas such as acinic cell carcinoma, mucoepidermoid carcinoma, adenocarcinoma NOS, salivary duct carcinoma, clear cell cribriform carcinoma and cystadenocarcinoma, among others.…”

Cytogenetic and immunohistochemical characterization of mammary analogue secretory carcinoma of salivary glands

“…There have been 11 reported cases in patients under 18 years of age [6,13,26,[29][30][31][32][33][34][35][36]. One of our cases with rearranged ETV6 involved a 12-year-old female making this the youngest reported MASC in literature.…”

Mammary analogue secretory carcinoma: A rare salivary gland tumour

“…[3] The majority of MASC cases were previously diagnosed as 'zymogen-poor' acinic cell carcinoma, but also have similar features to low-grade cribiform cystadenocarcinoma, adenocarcinoma not otherwise specified, and low-grade muco-epidermoid carcinoma. [9,10] Acinic cell carcinoma of the breast is composed of cells arranged in microcystic, solid and microglandular areas, and resembles acinic cell carcinoma of the salivary glands. The immunohistochemical and clinicopathological findings of salivary acinic cell carcinoma are similar to those of breast secretory carcinomas.…”