A case of IgG4-related lung disease associated with multicentric Castleman's disease and lung cancer.

A 67-year-old man with submaxillary lymphadenopathy diagnosed as reactive follicular hyperplasia of the lymph node was referred to us for pulmonary evaluation. Pathological findings of the lung and hilar lymph node biopsies showed the histological feature of Castleman's disease (CD). Interestingly, infiltrated plasma cells had strong immunoreactivity for IgG4. In addition, this patient had coexisting lung cancer. We believe this is the first described case of IgG4-related lung disease associated with multicentric CD (MCD) and lung cancer. To establish a therapeutic strategy for IgG4-related lung disease, the association between IgG4-related disease and MCD needs to be clarified.