Salivary Gland Neoplasms: Does Morphological Diversity Reflect Tumor Heterogeneity

Salivary gland tumor classification encompasses a vast list of benign and malignant neoplasms. Their morphological diversity is recognized not only between different entities but also within individual tumors. Tumor categories as described by the World Health Organization reflect, in part, a true genetic heterogeneity (e.g., translocations involvingCRTC1andCRTC3-MAML2 genes in mucoepidermoid carcinoma andMYB-NFIB fusion in adenoid cystic carcinoma). Carcinoma ex pleomorphic adenoma shows diversity in its histological appearance, but recurrent rearrangements onPLAG1 andHMGA2 are common to its benign precursor. More recently, new categories have been defined, like secretory carcinoma with the t(12;15) (p13;q25)ETV6-NTRK3 translocation and clear-cell carcinoma withEWSR1-ATF1fusion. Recent studies on cribriform adenocarcinoma of minor salivary gland origin and epithelial-myoepithelial carcinoma point to a correlation with their morphological features. All of these advances show that the search of a histogenetic and genetic basis for salivary gland tumors is helping to clarify morphological categories and unraveling new ones. Nevertheless, currently morphology is still the hallmark of tumor classification and the gold standard. The therapeutic options for advanced tumors remain very limited but the discovery of translocation-generated gene fusions and increased knowledge of the genomic information of salivary gland tumors is creating opportunities for the development of specific t...
Source: Pathobiology - Category: Pathology Source Type: research