Deep Pathological Phenotyping of Dermatomyositis with Different Autoantibodies

Objective: Dermatomyositis with different myositis-specific autoantibodies has distinctive clinical presentations. Pathological variation of patients with different antibodies has not been fully understood. Methods A retrospective review of muscle pathological features was performed in dermatomyositis patients with known myositis-specific antibodies. Results A total of 46 dermatomyositis patients with one myositis-specific autoantibody (anti-MDA5 11, anti-Mi-2 10, anti-NXP2 13, anti-TIF1γ 8, anti-SAE 4) were included and the pathological severity score was evaluated. Patients with anti-Mi-2 demonstrated higher pathological severity scores and apparent sarcolemmal complement deposition, which was in consistency of more severe muscle weakness and higher level of muscle enzymes. In contrast, patients with anti-MDA5 generally had minimal pathological changes in muscle with less inflammatory cell infiltration, fewer membrane attack complex deposition, and milder myxovirus resistance protein A upregulation. Patients with anti-SAE had more inflammatory cell infiltration and MAC deposition compared to anti-MDA5 group. Muscle pathological scores varied largely in patients with anti-NXP2 and anti-TIF1γ. Conclusion The muscle pathological features varies among dermatomyositis with different autoantibodies, which further indicates the heterogeneity of dermatomyositis.