Looking through the same lens - Immunohistochemistry for salivary gland tumors: A narrative review on testing and management strategies

Abstract

Salivary gland tumors are relatively uncommon neoplasms, presenting a diagnostic challenge for both clinicians and pathologists. When performing a biopsy, there is often an impasse between both specialists, with the clinician trying to remove as little tissue as possible and the pathologist in a perpetual quest for more. While immunohistochemistry (IHC), coupled with hematoxylin-eosin staining greatly helps in reaching a precise diagnosis and framing a management plan, there are no existing guidelines for the implementation of IHC panels in the diagnostic work-up of salivary gland tumors. The main objective of this review is to provide an up-to-date summary of the application of IHC in the diagnosis of salivary gland malignancies and the current treatment strategies. For this narrative review, we identified 50 meta-analyses and systematic reviews published between September 2013 and September 2023 using the PubMed and Google Scholar databases, with the keywords, “IHC in salivary gland tumors” and “immunohistochemistry in salivary gland tumors.” We excluded non-peer-reviewed articles, non-human studies, case reports, and series, and articles that were not in English or those for which the full text was not available; we included the remaining 18 articles in our qualitative data synthesis. To summarize the management strategy, we collated and included the key points from the National Comprehensive Cancer Network Clinical Practice Guidelines in Oncology (Head and Neck Cancers, Version 1), 2023 and the American Society of Clinical Oncology guidelines. Our findings reflect that IHC markers, in addition to offering significant prognostic insight and guiding surgical strategy, also help plan hormonal and targeted therapies. A thorough understanding of the clinical implications of various IHC markers ensures informed multidisciplinary communication and helps the clinician and pathologist see things from a common perspective, that is, through the same lens.