Diffuse Soft-Tissue Swelling in Antinuclear Matrix Protein-2 Antibody-Associated Dermatomyositis Sine Dermatitis

Abstract

A 66-year-old man presented with progressive weakness and myalgia for 3 months, followed by anasarca and dysphagia. Physical examination showed symmetric limb-girdle weakness and generalized edema without skin rashes. Creatine kinase was 1584 U/L (normal: <308). Muscle biopsy displayed inflammatory myopathy with perifascicular pathology (Figure 1). Myositis-specific antibody panel identified positive antinuclear matrix protein 2 (NXP2) autoantibody. Results of a whole-body computed tomography scan were normal except for subcutaneous and soft-tissue edema (Figure 2).