RT Journal Article SR Electronic T1 Case presentation: Should we always treat IgG4-related lung disease? JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP P1038 VO 44 IS Suppl 58 A1 Erik Baltaxe A1 Tiberiu Shulimzon A1 Amir Onn A1 Michael J. Segel YR 2014 UL http://erj.ersjournals.com/content/44/Suppl_58/P1038.abstract AB Introduction:IgG4-related lung disease (IgG4-RLD) is part of a spectrum of inflammatory diseases that share similar pathological features and elevated serum IgG4. Recently chest involvement in IgG4-RLD has been characterized clinically and radiologically. Most reports advocate prompt immunosuppressive therapy and describe a fast and good response. We report 3 cases of untreated IgG4-RLD that on follow-up have been clinically asymptomatic and radiologically stable or improved.Cases presentation:Case 1: 44 yr old female with cough and shortness of breath. Chest CT showed mediastinal lymphadenopathy and bilateral alveolar and peribronchovascular infiltrates. Core needle biopsy showed a thickened lung interstitium, dense lymphoplasmocytic infiltrate, vasculitis and 30-40 IgG4+ cells/hpf. Serum IgG4: 573 mg/dl. On follow-up symptoms resolved spontaneously and radiological findings have partially regressed. Case 2: 21 yr old male with productive cough and pleuritic chest pain. Chest CT showed a RUL solid mass with spiculated margins. Pathology from lobectomy showed lymphoplasmocytic infiltration without vasculitis. 20–25% IgG4+ cells. Serum IgG4: 416 mg/dl. Now asymptomatic. Case 3: 58 yr old male presented with an incidental finding on chest CT of pleural thickening. PET-CT showed retroperitoneal fibrosis, mesenteric panniculitis and aortitis. Pathology from a thoracic core needle biopsy showed densely fibrotic paucicellular pleura, and dense lymphoplasmocytic infiltrates in the lung. No IgG4+ cells. No asbestos bodies or silica particles. Serum IgG4: 177 mg/dl. Asymptomatic on follow-up.Conclusion:Immunosuppressive therapy may not be warranted in all cases of IgG4-RLD.