Secretory carcinoma in the parotid gland: A case report.

Secretory carcinoma (SC) is a rare salivary gland neoplasm characterized by the ETV6::NTRK3 gene fusion, and it has been recognized as a distinct entity in the World Health Organization Classification of Head and Neck Tumors since 2017. Case 1 involved a 21-year-old Japanese man who presented with a 1-year history of a slow-growing, painless mass in the right parotid gland. Ultrasonography and magnetic resonance imaging demonstrated a well-circumscribed, homogeneous tumor measuring 16x12x10 mm. The patient underwent superficial parotidectomy. Case 2 involved a 79-year-old Japanese man who noticed a mass in the right parotid region 3 weeks before presentation. Imaging studies revealed a tumor with irregular margins and heterogeneous internal features, measuring 21x16x15 mm. The patient underwent total parotidectomy with selective neck dissection. Histological examination revealed features consistent with SC in both cases. Immunohistochemically, the tumor cells were positive for S-100 protein, mammaglobin and cytokeratin 7. The diagnosis was further supported by detection of the ETV6::NTRK3 gene fusion using reverse transcription-polymerase chain reaction and Sanger sequencing. Both patients received postoperative radiotherapy at a total dose of 60 Gy. No evidence of local recurrence or distant metastasis has been observed during the follow-up period of 7 years in case 1 and 3 years in case 2.