[A case of systemic IgG4-related disease with bilateral pleural effusions]

An 85-year-old man was admitted for non-productive cough and bilateral pleural effusion on a chest X-ray film. Although his pleural effusion was exudative and showed an increased number of lymphocytes and a high level of adenosine deaminase, Mycobacterium tuberculosis infection, even with a microbiological culture, PCR and interferon-gamma release assay, was unverifiable. Cytology of his pleural effusion demonstrated plasmacytoid-like large atypical cells. Immunological tests showed high levels of IgG and IgG4 in both his serum and pleural effusion. A fluorodeoxyglucose-positron emission tomography (FDG-PET) scan showed uptake of FDG in orbital lesions, salivary glands, gastric wall, biliary system and lymph nodes (cervical, supraclavicular, axillary, hilar, mediastinal, along the lesser gastric curvature). Histological examination of an orbital pseudotumor and gastric mucosal biopsy revealed that numerous numbers of mostly IgG4 positive plasma cells, had accumulated. Based on these findings, systemic IgG4-related disease was diagnosed. Corticosteroid therapy was started and the volume of pleural effusion markedly declined. We report a rare case of IgG4-related disease accompanied by pleural effusion with a high level of ADA.