A case of prominent immunoglobulin G4 ‐positive lymphadenopathy in response to microscopic lung cancer

Immunoglobulin G4 (IgG4)‐related disease is established as a new clinical entity, characterized by high levels of plasma IgG4 and IgG4‐positive plasma cell infiltration. However, the elevation of plasma IgG4 and infiltration of IgG4‐positive cells have been observed in other diseases, including malignancy. We experienced a case of prominent IgG4‐positive lymphadenopathy, which was diagnosed as a reactive lesion in response to lung cancer. The...