Secretory Carcinoma with ETV6-NTRK3 Gene Fusion and Lymph Node Metastasis in Maxillary Gingiva: A Case Report with Pathological and Molecular Correlative Studies.

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.