Molecular and immunohistochemical markers in appendiceal mucinous neoplasms: A systematic review and comparative analysis with ovarian mucinous neoplasms and colorectal adenocarcinoma.

INTRODUCTION Appendiceal mucinous neoplasms (AMNs) represent a rare and diagnostically challenging group of tumors. This systematic review aims to summarize the reported molecular and immunohistochemical markers (IHC) associated with AMNs and compare them with ovarian mucinous neoplasms (OMNs) and colorectal adenocarcinoma (CRC). METHODS A comprehensive search was performed in PubMed/MEDLINE/PMC, Scopus, Embase, and Web of Science databases to identify studies looking at IHC and molecular markers in AMNs. Chi-squared and Fisher's exact tests were utilized to compare the marker expression across different tumor types. RESULTS We identified 27 articles reporting several potential biomarkers for distinguishing between different subtypes of AMNs. Mutations in KRAS, GNAS, and RNF43 emerged as notable biomarkers, with KRAS mutations being the most prevalent across all subtypes. Additionally, p53 IHC overexpression was associated with higher tumor grades. When comparing AMNs with OMNs, we observed a higher prevalence of CK20, CDX2, SATB2, and MUC2 IHC expression, as well as KRAS and GNAS mutations, in AMNs. Conversely, CK7 and PAX8 IHC expression were more prevalent in OMNs. Comparing AMNs with CRCs, we found a higher prevalence of TOPO1 and PTEN IHC expression, as well as KRAS and GNAS mutations, in AMNs. Conversely, nuclear β-catenin IHC expression, as well as TP53, APC, and PIK3CA mutations, were more prevalent in CRCs. CONCLUSION This systematic review identified possible markers for distinguishing AMNs and differentiating between AMNs, OMNs, or CRCs.