Salivary gland neoplasms are a morphologically heterogenous group of lesions that are often diagnostically challenging. In recent years, considerable progress in salivary gland taxonomy has been reached by the discovery of tumor type-specific fusion oncogenes generated by chromosome translocations. This review describes the clinicopathologic features of a selected group of salivary gland carcinomas with a focus on their distinctive genomic characteristics. Mammary analog secretory carcinoma is a recently described entity characterized by a t(12;15)(p13;q25) translocation resulting in an ETV6-NTRK3 fusion. Hyalinizing clear cell carcinoma is a low-grade tumor with infrequent nodal and distant metastasis, recently shown to harbor an EWSR1-ATF1 gene fusion. The CRTC1-MAML2 fusion gene resulting from a t(11;19)(q21;p13) translocation, is now known to be a feature of both low-grade and high-grade mucoepidermoid carcinomas associated with improved survival. A t(6;9)(q22-23;p23-34) translocation resulting in a MYB-NFIB gene fusion has been identified in the majority of adenoid cystic carcinomas. Polymorphous (low-grade) adenocarcinoma and cribriform adenocarcinoma of (minor) salivary gland origin are related entities with partly differing clinicopathologic and genomic profiles; they are the subject of an ongoing taxonomic debate. Polymorphous (low-grade) adenocarcinomas are characterized by hot spot point E710D mutations in the PRKD1 gene, whereas cribriform adenocarcinoma of (minor) salivary glands origin are characterized by translocations involving the PRKD1-3 genes. Salivary duct carcinoma (SDC) is a high-grade adenocarcinoma with morphologic and molecular features akin to invasive ductal carcinoma of the breast, including HER2 gene amplification, mutations of TP53, PIK3CA, and HRAS and loss or mutation of PTEN. Notably, a recurrent NCOA4-RET fusion has also been found in SDC. A subset of SDC with apocrine morphology is associated with overexpression of androgen receptors. As these genetic aberrations are recurrent they serve as powerful diagnostic tools in salivary gland tumor diagnosis, and therefore also in refinement of salivary gland cancer classification. Moreover, they are promising as prognostic biomarkers and targets of therapy.

Coordinator of the International Head and Neck Scientific Group Padua Italy

Department of Anatomical Pathology University of Calgary Foothills Medical Centre Calgary AB Canada

Department of Biomedical Sciences and Medicine Centre for Biomedical Research University of Algarve Faro Portugal

Department of Oncology and Radiotherapy Oncological Clinic Faculty of Medicine in Plzen Charles University

Department of Oncology Section Head and Neck Oncology KU Leuven Leuven Belgium

Department of Otolarygology Head and Neck Surgery Kobe University Graduate School of Medicine Kobe Japan

Department of Pathology Allegiance Health Jackson MI

Department of Pathology and Genetics Sahlgrenska Cancer Center University of Gothenburg Gothenburg Sweden

Department of Pathology University of Arkansas for Medical Sciences Little Rock AR

Department of Pathology University of Texas Southwestern Medical Center Dallas TX

Departments of Pathology

European Salivary Gland Society Geneva Switzerland

Molecular and Genetic Laboratory Biopticka Lab Ltd Plzen Czech Republic

Otorhinolaryngology

Otorhinolaryngology Head and Neck Surgery University Hospitals Leuven

University of Udine School of Medicine Udine Italy

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