Inflammatory Myositis in a Child due to Anti-NXP2 Antibody, First Case Report from India

We present a case of a 10-year-old boy with 1-month history of proximal more than the distal weakness of all four limbs with myalgias, contractures, and bulbar symptoms on a background history of exertional myalgias for 2 years. His power was grade two-three. Investigations showed elevated creatine phosphokinase (CPK). His auto-antibody profile showed anti- nuclear matrix protein 2 (NXP2) antibody positivity. Muscle magnetic resonance imaging (MRI) showed extensive T2 fat-saturated hyperintense signal changes in the glutei, thigh, and leg muscles suggestive of active myositis. He improved significantly with immunomodulation with steroids, intravenous immunoglobulins (Iv Ig), and mycophenolate mofetil (MMF). He was continued on monthly pulse steroids and MMF. He is on regular follow-up. This is a rare case of anti-NXP2 antibody-mediated inflammatory myositis and the first report from India.