Approaches to the diagnosis of secretory carcinoma of the salivary glands: a case series and review.

Secretory carcinoma (SC) is a salivary gland neoplasm included in the latest World Health Organization Classification of Head and Neck Tumours. Its morphologic and immunohistochemical characteristics resemble those of breast secretory carcinoma, and the tumors share the same fusion gene, ETV6::NTRK3. This chromosome translocation can be confirmed through reverse transcription-polymerase chain reaction or located using ETV6 fluorescent in situ hybridization. These techniques are expensive, and few laboratories can carry out molecular analysis. In addition, some of these tumors are related to non-NTRK fusion types and non-ETV6 translocation. Therefore, recognition of the typical histopathologic features of SC is the first step in considering this disease among the diagnostic hypotheses. In this case series, morphologic findings combined with immunohistochemical profiles were sufficient to make the correct diagnosis.