SERPINB2 and dermatomyositis: Reduced angiogenesis‐related SERPINB2+ monocytes (37.12% vs. 46.69% in NC) predicted better outcomes in IMNM (p = 0.006, HR = 0.264), whereas decreased HIF3A+CECs (14.29% in DM vs. 16.95% in NC), essential for endothelial barrier maintenance, negatively correlated with myofiber necrosis (p = 0.016, rho = −0.168) and were predictive of improved outcomes in DM (p = 0.014, HR = 0.412).