ETV6–NTRK3-positive parotid mammary analogue secretory carcinoma: a case report

Introduction: Mammary analogue secretory carcinoma (MASC) is a recent discovered entity of salivary glands tumors, reported for first time in 2010. The presence of a translocation encodes the ETS variant transcription factor 6–neurotrophic tyrosine receptor kinase (ETV6–NTRK3) gene fusion differences MASC from other tumors. Case presentation: A 68-year-old male showed a non-painful right parotid enlargement, came from dermatology service, and followed by some facial squamous cell carcinomas. A computed tomography (CT) scan showed a 1.7×1.6 cm right parotid enlargement in superficial lobe. The patient underwent a right superficial parotidectomy. The final pathology confirmed the presence of ETV6–NTRK3-positive MASC. Complete right deep parotidectomy and functional cervical emptying were performed. Discussions and Conclusions: It is necessary to establish an appropriated differential diagnosis between salivary gland tumors. MASC is a low-grade malignancy cancer that sometimes can evolve to a high-grade tumor that might produce local and distance dissemination. Most times, these tumors are only treated by surgical resection and evaluating by a multidisciplinary team the need of more treatments. In our case, the patient showed a primary parotid tumor, removed surgically with free edges, and being identified as MASC. We decided to underwent neck dissection and discovered a second MASC focus on cervical salivary gland; however, there was no nodal dissemination. The patient remains disease-free after 14 months from last surgery. It is important to keep studying genetic therapy targets to ETV6–NTRK3 to obtain a new therapy line to treat those cases that require.