Abstract
Immunoglobulin G4 (IgG4)-related lung disease is a disease in which IgG4-positive plasma cells and lymphocytes infiltrate lung tissues along with immunohistochemically evident fibrous interstitial proliferation in the background, in addition to hyper-IgG4 disease. The diagnosis of this disease can be difficult. Here, we report 2 cases with IgG4-related lung disease that was difficult to differentiate from malignant tumors because both cases had pulmonary lesions showing high standardized uptake values (SUV) on positron emission tomography (PET). Case 1: A 75-year-old man under treatment for autoimmune pancreatitis and diabetes mellitus was noted to have multiple nodular opacities in both lungs and a mass density in the right paravertebral region on computed tomography (CT). As high SUVmax was noted for both lesions on exploration by fluorodeoxyglucose (FDG)-PET/CT, an advanced malignant tumor was diagnosed and a video-assisted thoracoscopic (VATS) biopsy was performed and diagnosed IgG4-related lung disease. Case 2: A 48-year-old woman consulted our clinic with a chief complaint of bloody sputum. Chest CT revealed a mass density with 12-, 13-, and 16-mm spiculations in the S2 segment of the right upper lobe and irregular thickening of the pleura including the paravertebral region. The lesion was a mass showing high SUV in the S2 segment on FDG-PET. Malignancy was suspected from the imaging findings, and a VATS biopsy was performed and diagnosed IgG4-related lung disease. Actively undertaking VATS biopsy in cases with this disease is valuable for making the differential diagnosis between malignant tumors and IgG4-related lung disease, since the diagnosis can be difficult in some patients showing high SUV.
Highlights
Immunoglobulin G4 (IgG4)-related lung disease is a disease in which IgG4-positive plasma cells and lymphocytes infiltrate lung tissues along with immunohistochemically evident fibrous interstitial proliferation in the background, in addition to hyper-IgG4 disease [1]
We present 2 cases in our experience in which malignant lesions were suspected on diagnostic imaging but IgG4-related lung disease was diagnosed based on video-assisted thoracoscopic (VATS) biopsy
Case 1 A 75-year-old Japanese man presenting with no respiratory symptoms, who was being treated elsewhere for autoimmune pancreatitis and diabetes, was referred to our clinic because of abnormal opacities noted on computed tomography (CT) of the chest
Summary
Immunoglobulin G4 (IgG4)-related lung disease is a disease in which IgG4-positive plasma cells and lymphocytes infiltrate lung tissues along with immunohistochemically evident fibrous interstitial proliferation in the background, in addition to hyper-IgG4 disease [1]. FDG-PET/CT scans disclosed a nodular lesion measuring 35 × 13 mm in size in the right S7 segment with a maximum standardized uptake value (SUV max) of 8.4, multiple lesions in both lungs, and high-SUV areas in the hilar lymph nodes (Figure 2). The mass lesions in the S2 segment appeared as increased uptake with values of 3.4, 5.1 and 5.2 SUV, respectively, on FDG-PET scan (Figure 6). Blood chemical laboratory data showed no abnormal value and no elevations of tumor markers, a lung biopsy was performed under VATS to determine a treatment policy as malignancy was Figure 2 FDG-PET view. FDG-PET/CT scans disclosed a nodular lesion measuring 35 × 13 mm in size in the right S7 segment with a maximum standardized uptake value (SUVmax) of 8.4. The serum IgG4 level was slight elevated at 150 mg/dL, and a diagnosis of IgG4-related lung disease was made
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