[A case of pulmonary inflammatory pseudotumor accompanied with increased serum immunoglobulin G levels and autoimmune pancreatitis].

A 77-year-old man with increased serum immunoglobulin G levels and autoimmune pancreatitis was found to have a chest X-ray abnormality. The chest X-ray and CT films showed a mass shadow in the right lower lobe and lymphadenopathy. Since transbronchial tumor biopsy did not obtain diagnostic material, CT-guided cutting needle biopsy was performed. The microscopic findings showed plasma cells and lymphocytes infiltrating the pleura and alveolar interstitium. A diagnosis of inflammatory pseudotumor was suspected, but it was difficult to exclude malignancy. Therefore, wedge resection of the right lower lobe including the mass and incisional biopsy of mediastinal lymph nodes were performed. Histopathologic examination of the resected specimen revealed inflammatory pseudotumor that was predominantly composed of mature plasma cells infiltrating in the bronchiolar wall, peribronchiolar interstitial tissue, alveolar wall, visceral pleura, the diaphragmatic area of the parietal pleura and mediastinal lymph nodes. Immunohistochemical staining revealed many IgG4-positive plasma cells diffusely infiltrated in the resected mass and lymph nodes. In this case, there is a possibility that patient developed autoimmune pancreatitis, pulmonary inflammatory pseudotumor and lymphadenopathy as part of systemic IgG4-related