Mammary analogue secretory carcinoma of salivary glands: a new entity associated with ETV6 gene rearrangement
Abstrakt
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 suspiciou 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 carcinomasmet the criteria ofMASC, as they exhibited a typical appearance with solid/microcystic and papillary architecture and intraluminal secretions, and cells completely evoid of basophilic cytoplasmic zymogen granules indicative f true acinar differentiation. The only paediatric case was n unencapsulated tumour composed of macrocystic tructures covered by a mostly single but, focally, double layer f cells with apocrine morphology.
In all cases, the neoplastic ells revealed immunoreactivity for S100, mammaglobin, ytokeratin CK7, CK8, STAT5a and vimentin. FISH for TV6 gene rearrangement was positive in six out of seven ases, and RT-PCR was positive in three cases.
MASC is a ew entity of malignant epithelial salivary gland tumours not ncluded in the 2005 WHO Classification of Head and Neck umours. There is a growing body of evidence that it is not as are as was assumed, as is also indicated by our series (3.8%). n most cases, MASC shares some microscopic features with ciCC, adenocarcinoma/cystadenocarcinoma NOS and lowgrade EC.
In rare cases, MASC with high-grade transformation ay mimic the morphological appearances of highgrade alivary gland malignancies, such as salivary duct arcinoma.