Diagnosis and Treatment of Secretory Carcinoma of the Oral Cavity: Report of Two Cases and Pooled Analysis of the Recent Literature

Abstract

Background: Secretory carcinoma (SC) is a malignancy of the salivary glands, which is similar to SC of the breast in terms of its association with neurotrophic tyrosine receptor kinase (NTRK) fusion-positive gene. SC is a recently described salivary gland tumor, and there are few reports describing oral minor salivary gland-derived SC. We reported two cases of SC in the oral cavity and reviewed the literature.Case presentation: The patients included a 65-year-old Japanese woman presented with a mass of the upper lip and an 84-year-old Japanese man presented with a mass on the buccal mucosa, respectively. Diagnosis was based on histomorphological and immunohistochemical findings and identification of a specific translocation of the ETS variant 6-neurotrophic receptor tyrosine kinase 3 (ETV6-NTRK3) gene fusion. Case 1 was finally diagnosed using reverse transcription-polymerase chain reaction using formalin-fixed paraffin-embedded tissue samples, while case 2 was diagnosed using fluorescence in situ hybridization analysis. Conclusion: It is highly likely for many cases of SC to be initially diagnosed as acinic cell carcinoma (AciCC) owing to their similar histological findings. The treatment strategy for minor salivary gland-originated SC is the same as that for AciCC, but SC is often highly malignant and involves a high risk of cervical lymph node metastasis. Making an accurate diagnosis in cooperation with pathologists and confirming the presence of the ETV6-NTRK3 fusion gene using genetic analysis is important.