Introduction:
Although neoplasms of the salivary glands are relatively rare, they are nevertheless characterized by a variety of biologies and prognoses. According to the most recent WHO classification of salivary gland tumors, these are mostly benign but they can nevertheless present with different grades of malignancy. Secretory carcinoma (SC), a malignant tumor affecting the salivary glands of the head and neck, was recently reclassified in the light of molecular analysis in 2017; before that date it was considered a mammary analogue secretory carcinoma (MASC). Acinic cell carcinoma (ACC) is a low grade salivary gland malignancy characterized by serous acinar differentiation. It is important to understand the growth patterns and the differences between SC and ACC as they are similar histologically. Unlike ACC, SC pathognomonically expresses the ETV6-NTRK3 gene fusion, a characteristic permitting pathologists to formulate the diagnosis of a SC with regards to a lesion originally considered ACC. Although both SC and ACC are characterized by a generally favorable prognosis and non-aggressive behavior, high grade SC tumors have been described, and, according to some reports, they are characterized by a higher rate of lymph node involvement and distant metastases. Since it has only recently been reclassified, SC may be confused with other tumors of the salivary glands and incorrectly diagnosed. The current work, which reports on a case of SC of the submandibular gland originally diagnosed as a low grade mucoepidermoid carcinoma, examines some of its clinical, genetic and immunohistochemical features.