IgG4-related disease: a great mimicker of lung cancer.

IgG4-related disease is a rheumatological disorder, affecting multiple organ systems, and displaying dense lymphoplasmacytic inflammatory infiltrate and storiform fibrosis on histology. The pulmonary manifestations of IgG4-related disease are varied. Most commonly, bronchovascular consolidation and perilymphatic parenchymal thickening occur. IgG4-related disease can present as a solitary parenchymal mass and is often mistaken for a primary pulmonary or haematological malignancy. This report presents a case of IgG4-related disease in a patient with 6 months reported haemoptysis symptomatology and CT findings of perihilar lymphadenopathy, multiple pulmonary parenchymal nodules and a single parenchymal mass. Clinician cognisance of the histopathological presentation of IgG4-disease is important. It should be considered as a differential in patients for which investigations have ruled out malignancy, as it is responsive to glucocorticoids in the majority of cases.