Mammary analogue secretory carcinoma (MASC): A literature review and report of two cases

Abstract

Introduction: Mammary analogue secretory carcinoma (MASC) is a rare salivary gland tumour. It is generally a low-grade lesion that presents as a slow growing painless swelling with an indolent course with good survival. Diagnosis is typically via the highly specific ETV6- NTKR3 gene fusion with the translocation t(12;15)(q13;q25). Method: A literature review was conducted through PubMed, Cochrane, and Medline. We also present two cases. Results: Although typically regarded as a low-grade lesion, highgrade features, such as nodal metastases, more solid and trabecular architecture with necrosis, and the ETV6-X fusion gene, have been described. Our cases were diagnosed through morphologic and immunohistochemical features despite absence of the classic fusion gene. Conclusion: MASC can be diagnosed in absence of the highly specific ETV6-NTKR3 in presence of certain morphologic and immunohistochemical features. Although it is a typically low-grade lesion, several high-grade features have been described that may require further treatment. Keywords: head and neck neoplasms; salivary gland; parotid gland; salivary gland neoplasms; parotid neoplasms; immunohistochemistry; mammary analogue secretory carcinoma.