A Case of Secretory Carcinoma of the Submandibular Gland Harboring an ETV6-X Fusion Gene

Secretory carcinoma (SC) is a low-grade salivary gland carcinoma similar to secretory breast carcinoma harboring the ETV6-NTRK3 fusion gene, that was first proposed as a distinct disease entity in 2010 by Skálová et al. SC has heterogeneous histopathological manifestations, so that definitive diagnosis of the tumor by histopathological examination is difficult. Many fusion partners of ETV6 are known in other malignant tumors. In the case of SC also, previously unknown fusion partners of ETV6 (ETV6-X) have been reported recently. Herein, we report a case of SC of the submandibular gland harboring an ETV6-X fusion gene. A 32-year-old man presented to our department with a mass in his right submandibular region that he had first noticed one month earlier. We diagnosed the mass as a submandibular gland tumor and performed submandibular gland excision. The postoperative histopathological findings led to suspicion of the tumor as a SC. Subsequently, FISH analysis led to a confirmed the diagnosis of SC with an ETV6-X fusion gene. No evidence of recurrence was noted during postoperative follow-up of the patient for 20 months without any further therapy. Because of the difficulty in the histological diagnosis and absence of any availability of established treatments for tumors harboring the NTRK family genes, it is important to perform genetic examination for confirmatory diagnosis in patients with suspected SC.