Salivary gland secretory carcinoma with an ETV6::RET fusion: A case report

The present study reports the case of a 25-year-old male patient with salivary gland secretory carcinoma (SC) with the ETV6::RET gene fusion. The patient presented with a left parotid mass and was treated using a superficial parotidectomy. Histological analysis of the tumor demonstrated a combination of cystic, follicular and trabecular patterns in cells, with eosinophilic secretions and a vacuolated cytoplasm. Tumor cells exhibited infiltrative growth into muscle and nerve tissues, accompanied by central stromal hyalinized sclerosis. Immunohistochemically, the tumor cells were positive for S-100, mammaglobin and GATA binding protein 3, and negative for DOG1. The results of the present case demonstrated that the patient possessed SC with the ETV6::RET gene fusion. Following the operation, the patient underwent radiotherapy, leading to a disease-free state at the last follow-up at 1 year and 3 months following surgery. A comprehensive review of 21 SC cases with this gene fusion, including the case reported in the present study, demonstrated that invasive growth, neural and lymphovascular invasion and hyalinized sclerosis were frequently seen on histology, and 11 cases (52%) exhibited advanced-stage disease (>T3 or M1). Thus, salivary gland SC with an ETV6::RET fusion may show infiltrative growth and may be more aggressive compared with salivary gland SC with an ETV6::NTRK3 fusion, which is often associated with an indolent clinical course. Therefore, confirmation of the genetic profile of SC is crucial for the prediction of patient prognosis and administration of an effective therapeutic course.