IgG4 Related Lung Disease

A 70-year-old woman was found to have an incidental left lower lobe lung mass on chest radiograph in setting of lower respiratory tract infection symptoms. She is an exsmoker but with long history of smoking since the age of 18 years. Past medical history includes breast cancer that was treated with wide local excision and nodal dissection 7 years earlier. Apart from very short duration of lower respiratory tract symptoms patient denied history of chronic cough or hemoptysis. However, patient revealed 14 kilograms of weight loss over a period of 4 years. Further investigation with computed tomography (CT) demonstrated a 3.9 cm spiculated mass in the left lower lobe with an 8mm satellite nodule. Patient subsequently underwent a positron emission tomography (PET) scan that demonstrated an intensely avid left lower lobemasswith standardized uptake value (SUV) max of 18.82. Satellite nodule, ipsilateral hilar, and mediastinal lymph nodes showed lowgrade FDG uptake (Figures 1(a), 1(b), and 2). These findings were suggestive of primary lungmalignancy with T3, N2, and M0 disease. Patient’s serum IgG count was normal 10 g/L with normal reference range of 7.5−15.6 g/L. Serum IgG4 test was not performed. Patient underwent a CT guided biopsy of the left lower lobe mass that demonstrated inflammatory fibroblastic lesion. However due to high clinical suspicion of primary lungmalignancy, left lower lobectomy was performed. Histological examination revealed lymphoplasmacytic infiltration with mainly IgG4 positive plasma cells. Hence IgG4 related pulmonary inflammatory pseudotumour was diagnosed. 2. Discussion