A new location for pediatric immunoglobulin G4 related disease: the biceps muscle.

BACKGROUND Immunoglobulin G4 (IgG4)-related disease (IgG4-RD) is a systemic disorder of unknown etiology characterized by elevated serum IgG4 and tissue infiltration of IgG4-positive plasma cells. The disease was described in the pancreas, aorta, thyroid, salivary glands, periorbital tissues, kidneys, pericardium and lymph nodes. CASE Here in, we report a first pediatric case report of IgG4-related disease who presented with a mass in skeletal muscle i.e., biceps muscle. CONCLUSION To the best of our knowledge, the involvement in skeletal muscle has previously not been reported in children.