Cavitating lung disease: A novel presentation of IgG4-related disease

Objective: Rare disease Background: Immunoglobulin (Ig) G4-related disease, previously referred to as IgG4-related sclerosing disease or hyper-IgG4 disease, may occur in the lung, involving alveolar parenchyma, airways, and pleura. Various pulmonary manifestations of IgG4-related disease have been reported, but to the best of our knowledge a cavitating lung disease has not been reported previously. Case Report: We describe a 60-year-old man who presented with hemoptysis and cavitating lung disease with clinical, laboratory, and histopathologic findings compatible with IgG4-related disease. Other potential causes of cavitation were excluded. Treatment was initiated with oral prednisone and subsequently mycophenolate mofetil was added. Follow-up 1 year later shows stable pulmonary function with complete resolution of the cavitary lesions. Conclusions: We present a case of cavitating lung disease as a previously unreported manifestation of IgG4-related disease. Our patient had an excellent response to immunosuppression. An increased awareness of IgG4-related disease and its myriad of manifestations is very important for pulmonologists.