Acinic cell carcinoma (AciCC) is a common salivary gland malignancy, typically composed of neoplastic acinic cells with zymogen granules. The vast majority of cases are driven by a t(4;9)(q13;q31) leading to enhancer hijacking and upregulation of the NR4A3 gene. However, a minority of cases do not display NR4A3 overexpression on immunohistochemical examination and are negative for the rearrangement involving the NR4A3 gene when tested by FISH. Such cases overexpress NR4A2, and the protein product is detectable by immunohistochemistry. In this study, we aimed to assess the utility of NR4A2 and NR4A3 immunohistochemistry in the differential diagnosis of salivary gland tumors. Eighty-five cases of classic low-grade ACiCC, as well as 36 cases with high-grade transformation (HGT) and 7 high-grade AciCC cases were included in the analysis. NR4A3 was at least focally positive in 105/128 (82%) cases. Out of the 23 cases that were immunohistochemically negative for NR4A3, 6 displayed nuclear immunopositivity with the NR4A2 antibody. The NR4A3 rearrangement was confirmed by FISH in 38/52 (73%) cases. In addition, this is the first report of an NR4A2 rearrangement being detected by FISH in 2 AciCC cases that were negative for the NR4A3 rearrangement. Our analysis confirms that the majority of AciCC, including high-grade cases and cases with HGT, are immunopositive for NR4A3, and suggests that NR4A3 immunohistochemistry is a powerful tool in the differential diagnosis of salivary gland tumors. However, its utility is limited in sub-optimally fixed samples which often display weaker and focal positivity. Our study also indicates that in a minority of cases, AciCC might be negative for NR4A3 immunostaining, because the pathogenic genetic event in these cases is instead a rearrangement involving the NR4A2 gene.

• Keywords
• 9)(q13, Acinic cell carcinoma, High-grade transformation, NR4A2, NR4A3, Salivary gland, q31) translocation, t(4,
• MeSH
• Carcinoma, Acinar Cell * diagnosis   genetics   metabolism   MeSH
• Cell Nucleus pathology   MeSH
• DNA-Binding Proteins metabolism   MeSH
• Immunohistochemistry MeSH
• Nuclear Receptor Subfamily 4, Group A, Member 2 metabolism   MeSH
• Humans MeSH
• Biomarkers, Tumor analysis   MeSH
• Salivary Gland Neoplasms * diagnosis   genetics   pathology   MeSH
• Receptors, Thyroid Hormone metabolism   MeSH
• Salivary Glands pathology   MeSH
• Receptors, Steroid * genetics   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• DNA-Binding Proteins MeSH
• Nuclear Receptor Subfamily 4, Group A, Member 2 MeSH
• Biomarkers, Tumor MeSH
• NR4A2 protein, human MeSH Browser
• NR4A3 protein, human MeSH Browser
• Receptors, Thyroid Hormone MeSH
• Receptors, Steroid * MeSH

This review gives a brief history of the development of head and neck pathology in Europe from a humble beginning in the 1930s to the explosive activities the last 15 years. During the decades before the introduction of immunohistochemistry in the 1980s, head and neck pathology grew as a subspeciality in many European countries. In the late 1940s, the Institute of Laryngology and Otology with its own pathology laboratory was founded in London, and in 1964 the World Health Organization (WHO) International Reference Centre for the Histological Classification of Salivary Tumours was established at the Bland-Sutton Institute of Pathology, also in London. International collaboration, and very much so in Europe, led to the publication of the first WHO Classification of Salivary Gland Tumours in 1972. In the 1960s, a salivary gland register was organised in Hamburg and in Cologne the microlaryngoscopy was invented enabling microscopic endoscopic examination and rather shortly afterwards a carbon dioxide laser attached to the microscope became established and laryngeal lesions could be treated by laser vaporisation. During the last three decades, the use of immunohistochemistry supplemented with cytogenetic and refined molecular techniques has greatly facilitated the pathological diagnostics of head and neck lesions and has had a huge impact on research. Collaboration between different European centres has drastically increased partly due to establishment of scientific societies such as the Head and Neck Working Group (HNWG) within the European Society of Pathology and the International Head and Neck Scientific Group (IHNSG). A very large number of European pathologists have contributed to the 2nd, 3rd and 4th WHO books, and are involved in the upcoming 5th edition. Accredited educational meetings and courses are nowadays regularly arranged in Europe. Numerous textbooks on head and neck pathology have been written and edited by European pathologists. The increased collaboration has created larger series of tumours for research and new entities, mainly defined by their genetic abnormalities, are continuously emerging from Europe, particularly regarding salivary gland neoplasms and "undifferentiated" sinonasal tumours. These findings have led to a better and more precise classification and open the possibilities for new treatment strategies.

• Keywords
• Cancer, Head and neck pathology, History of European head and neck pathology, Laryngeal neoplasms, Salivary neoplasms, Sinonasal neoplasms,
• MeSH
• Humans MeSH
• Head and Neck Neoplasms * diagnosis   MeSH
• Salivary Gland Neoplasms * MeSH
• Salivary Glands MeSH
• World Health Organization MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Geographicals
• Europe MeSH

Diagnosis of salivary gland neoplasms is often challenging due to their high morphological diversity and overlaps. Several recurrent molecular alterations have been described recently, which can serve as powerful diagnostic tools and potential therapeutic targets (e.g. NTRK or RET fusions). However, current sequential molecular testing can be expensive and time consuming. In order to facilitate the diagnosis of salivary gland neoplasms, we designed an all-in-one RNA-based next generation sequencing panel suitable for the detection of mutations, fusions and gene expression levels (including NR4A3) of 27 genes involved in salivary gland neoplasms. Here we present the validation of the "SalvGlandDx" panel on FFPE histological specimen including fine needle aspiration (FNA) cell block material, against the standard methods currently used at our institution. In a second part we describe selected unique cases in which the SalvGlandDx panel allowed proper diagnosis and new insights into special molecular characteristics of selected salivary gland tumors. We characterize a unique salivary gland adenocarcinoma harboring a ZCCHC7-NTRK2 fusion, a highly uncommon spindle cell and pseudoangiomatoid adenoid-cystic carcinoma with MYBL1-NFIB fusion, and a purely oncocytic mucoepidermoid carcinoma, whereas diagnosis could be made by detection of a CRTC3-MAML2 rearrangement on the cell block specimen of the FNA. Further, a rare case of a SS18-ZBTB7A rearranged low-grade adenocarcinoma previously described as potential spectrum of microsecretory adenocarcinoma, is reported. In addition, features of six cases within the spectrum of polymorphous adenocarcinoma / cribriform adenocarcinoma of salivary gland including PRKD1 p.E710D mutations and novel fusions involving PRKAR2A-PRKD1, SNX9-PRKD1 and ATL2-PRKD3, are described.

• Keywords
• Biopsy, Comprehensive, FNA, Molecular, Salivary gland neoplasm, Testing,
• MeSH
• Biopsy MeSH
• Oncogene Proteins, Fusion genetics   metabolism   MeSH
• In Situ Hybridization, Fluorescence MeSH
• Immunohistochemistry methods   MeSH
• Humans MeSH
• Mutation MeSH
• Biomarkers, Tumor * MeSH
• Cell Line, Tumor MeSH
• Salivary Gland Neoplasms diagnosis   drug therapy   genetics   MeSH
• Neoplasm Staging MeSH
• Gene Expression Profiling * methods   MeSH
• Neoplasm Grading MeSH
• High-Throughput Nucleotide Sequencing * methods   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Oncogene Proteins, Fusion MeSH
• Biomarkers, Tumor * MeSH