KRT84 (keratin 84) is a type II intermediate filament protein with primary roles in structural organization of the epidermis, hair follicles, and nails 1. KRT84 is expressed specifically in hair fiber cuticles and is regulated by HOXC13 transcription factor during hair follicle differentiation 12. Mechanistically, KRT84 function can be modulated through lysine 48-linked polyubiquitination by the E3 ubiquitin ligase RNF187, which promotes cell proliferation when KRT84 is degraded 3. Clinically, KRT84 demonstrates significant disease relevance across multiple conditions. In oral squamous cell carcinoma (OSCC), KRT84 acts as a tumor suppressor with decreased expression correlating with advanced tumor grade, stage, and poor overall survival 4. Conversely, KRT84 was downregulated in DSG3-overexpressing oral cancer cells, linking it to altered cellular adhesion and keratinocyte differentiation processes 5. Beyond malignancy, KRT84 emerged as a circulating blood biomarker inversely correlating with aortic diameter in thoracic aortic aneurysm patients, suggesting potential diagnostic utility 6. Additionally, KRT84 was identified as a citrullinated autoantigen in rheumatoid arthritis synovial tissues with elevated autoantibodies in RA patient serum 7, and shows etiology-dependent mutation patterns in hepatocellular carcinoma 8. These findings position KRT84 as a multifunctional protein with prognostic and diagnostic biomarker potential across diverse pathologies.