IgG4 related pleural disease: Recurrent pleural effusion after COVID-19 vaccination.

IgG4-related disease is characterized by a systemic fibroinflammatory process associated with substantial infiltration by plasma cells with IgG4 in the organs. Our patient presented with pleural effusion, and was diagnosed with IgG4-related lung disease (IgG4-RLD) after he received two doses of the Pfizer COVID-19 vaccine. The patient developed dyspnea and hypoxia 2 weeks after receiving the second dose of the Pfizer COVID-19 vaccine.