IgG4-related Pleural Disease Presenting as a Massive Bilateral EffusionIshida, Atsuko MD*; Furuya, Naoki MD*; Nishisaka, Takashi MD†; Mineshita, Masamichi MD*; Miyazawa, Teruomi MD, PhD*Journal of Bronchology & Interventional Pulmonology: July 2014 - Volume 21 - Issue 3 - p 237–241 doi: 10.1097/LBR.0000000000000082 Case Reports Abstract Author Information A 74-year-old woman with massive bilateral pleural effusion, which was exudative in nature, and with mononuclear cell predominance underwent a pleuroscopy. Parietal pleura were thickened and partly reddish in color. Biopsy specimens taken from the parietal pleura revealed lymphoplasmacytic inflammation with fibrosis. As her performance status rapidly worsened with thoracentesis, we performed bilateral pleurodesis using talc. Pathologic evaluation of the pleural biopsy specimen with immunohistochemical staining revealed 91 IgG4-positive plasma cells per high-power field and an IgG4/IgG ratio of 91%. Thus, the diagnosis of pleuritis from IgG4-related disease was established. Our case suggests that IgG4-related disease is one of the causes of pleural effusion, and it should be included in the differential diagnosis of unexplained pleuritis. *Department of Internal Medicine, Division of Respiratory and Infectious Diseases, St Marianna University School of Medicine, Kawasaki †Department of Pathology, Hiroshima Prefectural Hospital, Hiroshima, Japan Disclosure: There is no conflict of interest or other disclosures. Reprints: Teruomi Miyazawa, MD, PhD, 2-16-1 Sugao, Miyamae-ku, Kawasaki, Japan 216-8511 (e-mail: email@example.com). Received July 9, 2013 Accepted April 29, 2014 © 2014 by Lippincott Williams & Wilkins.