Aims: Carcinoma Ex Pleomorphic Adenoma (CXPA) is a malignant salivary gland tumour (SGTs) which is difficult to characterise due to the diversity of its histological subtypes. SGTs have attracted significant attention as there are therapeutic targets based on gene expression. Although the literature on rare and novel biomarkers is insufficient for meta-analysis, emerging research directions are important to guide further research. Methodology: Systematic review of MEDLINE, CINAHL, Embase, Scopus, Web of Science (BIOSIS), Cochrane CENTRAL, Informit, OpenDOAR, and GreyNet International from inception to 31st October 2022 for all English-language literature pertaining to 'carcinoma ex pleomorphic adenoma'. Diagnostic and prognostic biomarkers with two or less patient cohorts were reviewed. This is a subgroup study of unpublished data from a comprehensive systematic review of 495 studies. Results: Twenty-four papers with novel biomarkers met inclusion criteria. Incidence was reported in six papers. Incidence for NOTCH1 was 8.3% (n=3/32); neurotrophic tyrosine kinase receptor (NTRK) was 12.5% (n=1/8); tyrosine kinase receptor B (TrkB) was 50% (n=6/12 with salivary duct carcinoma subtype); BRCA1/2 gene mutations was 60% (n=27/45); and ALK 0% (n=0/38). Three studies in GLUT1 did not have an incidence. Structural differences were examined in 15 papers, including different extracellular matrix proteins, claudin-1, and calponin. Proteomics were examined in two papers. Differences include lower APOA1, higher SLC4A1, and higher SYCP1. Markers in malignant transformation include Cripto-1, LRPB1, MUC-1, Peroxiredoxin I, PDGF-A, and PDGF receptor. Three papers examined diagnostic biomarkers: two on fatty acid synthase enzyme, one on mammaglobin. Two papers examined predictive biomarkers for immunotherapy: one on PDL1, one on DCLK1. Conclusions: Application of rare molecular factors in CXPA is not well-clarified. Panels to identify therapeutic targets should be considered for CXPA.