A case of mammary analogue secretory carcinoma of the salivary gland (MASC) diagnosed originally as acinic cell carcinoma

Abstract

Background : We report the case of a 24- year-old male with mammary analogue secretory carcinoma arising from the right accessory parotid gland, which had initially been diagnosed both cytologically and histologically as acinic cell carcinoma.
Case : Morphological similarities between the resected tumor and mammary secretory carcinoma, such as the abundant secretory material within the follicular structures, prompted us to examine the resected tissue for the ETV6-NTRK3 chimeric fusion gene, which confirmed the diagnosis of MASC. Although we reviewed the cytological findings of this tumor as compared to those of acinic cell carcinoma, there were no definitive characteristic cytological findings other than the mucous globular structures and scant zymogen granules.
Conclusion : For a conclusive diagnosis for MASC, we should perform RT-PCR for confirming the presence of the fusion gene generated by chromosomal translocation after careful evaluation of the mammary secretory carcinoma-like morphology and immunohistochemistry.