One case of facial salivary gland secretory carcinoma and a literature review.

Background: To explore the clinical and pathological characteristics, as well as the immunophenotypes, of facial salivary gland secretory carcinoma and to improve the understanding of this disease. Method: Clinical data of a case of facial salivary gland secretory carcinoma occurring on the face were summarized. HE and immunohistochemical staining were performed to observe its morphological and immunophenotypic characteristics, and relevant literature was reviewed. Result: The patient was an elderly male. Facial Color Doppler ultrasound showed that a slightly hypoechoic solid mass was observed between the fat layer and muscle layer of the left cheek. Under the microscope, the tumor cells exhibited eosinophilic staining and displayed cystic and papillary infiltrative growth, with papillary structures lined by spiculated cells. In some areas, the tumor cells appeared solid and microcystic. The tumor was encapsulated and presented a cystic appearance. It grew in a lobulated and nest-like pattern, with fibrous capsules separating the lobules, and exhibited papillary, microcystic, and tubular growth patterns. The nuclei were round or oval, arranged in an orderly manner, with vacuolated cytoplasm, fine chromatin, and centrally located nucleoli. Immunohistochemistry showed S100 (+), MUC4 (+), and DOG1 (-). The molecular test results showed that NTRK3 gene translocation was positive. Conclusion: Facial salivary gland secretory carcinoma (SC) is a rare, low-grade malignant salivary gland tumor, mainly occurring in the parotid gland. ETV6-NTRK3 gene translocation is the most reliable basis for diagnosing SC. Combining morphological diagnosis with gene testing is not difficult.