In case 2, the man's 71-year-old father, who had been receiving long-term statins (>10 years), ezetimibe (>1 year), and recent proprotein convertase subtilisin/kexin type 9 inhibitor (1 month), had Achilles tendon thickening but no FDG uptake despite age and coronary artery disease history.<h4>Discussion</h4>These findings show that xanthomas exhibit persistent metabolic activity despite short-term lipid lowering, whereas prolonged therapy may attenuate inflammation. Here, PCSK9 is linked to xanthoma.