Salivary Gland Neoplasms: Does Morphological Diversity Reflect Tumor Heterogeneity

Abstract

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 involving CRTC1 and CRTC3-MAML2 genes in mucoepidermoid carcinoma and MYB-NFIB fusion in adenoid cystic carcinoma). Carcinoma ex pleomorphic adenoma shows diversity in its histological appearance, but recurrent rearrangements on PLAG1 and HMGA2 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 with EWSR1-ATF1 fusion. 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 targeted therapies.

Cell adhesion molecules’ altered profile in benign and malignant salivary gland tumors. The paradigm of beta4-integrin, desmoglein-2, ICAM-1 and CD44s

“…Instead of the limited expression of HCAM (CD44s) in myoepithelial and rarely in ductal cells that observed by Xing et al [26], many other studies have detected a more intense expression for HCAM (CD44s) and its isoforms in salivary gland tissues [27,36,37,51]. Similarly, we found strong membranous immunoreactivity in acinar cells (mainly serous), which decreased in intercalated and striated ductal cells.…”

Clear Cell Morphology in a Salivary Gland Tumor - Clearly a Morphological Dilemma

“…Among oncocytic major salivary gland tumors, 84% occurs in the parotid gland with male to female ratio of 1:1. [4,5] Nisha J Marla* and Poorni Bharathi T Most salivary gland tumors can be diagnosed purely on hematoxylin and eosin stained slides but clear cell tumors are an exception and generally require special stains, immunohistochemistry and even electron microscopy. Warthin's tumor without significant lymphoid cells can be misinterpreted as an Oncocytoma.…”

“…The cytoplasm shows granular positivity with phosphotungstic acid hematoxylin (PTAH) stain and antimitochondrial antibody, and large numbers of mitochondria are seen on ultrastructural examination. [3,4] Here we report a rare case of Clear cell salivary oncocytoma.…”

Evaluation of Fascin Expression in Selected Salivary Gland Tumors (An immunohistochemical study)

“…Alaa E.Ebrahim (1) , Nadia A. Radi (2) and Eman A. Abo Hager (3) (102) Alaa E. Ebrahim, et al ADJ-for Grils, Vol. 6, No.…”

“…Salivary gland tumors are a set of diseases which represent important lesions of oral and maxillofacial pathology (1) .They represent the main histologically heterogeneous group of human tumors with probably the greatest morphological diversity and cellular features and considering a specific tumor into a single category is neither always dependable nor straightforward (2) . So any mistakes in the diagnosis are…”