PMC9079228_01
A chest radiograph revealing left pleural effusion.
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Chest radiography revealed moderate left pleural effusion (Fig. 1).
18F-fluorodeoxyglucose (FDG) positron emission tomography and computed tomography showing accumulation of FDG in the mediastinum.
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Fluorodeoxyglucose (FDG) positron emission tomography imaging revealed FDG accumulation in the mediastinal and cervical lymph nodes (Fig. 2).
Contrast-enhanced computed tomography showing the absence of lymphadenopathy or pleural thickening in the mediastinum.
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Neither lymphadenopathy nor pleural thickening was detected on contrast-enhanced computed tomography of the neck to the pelvis (Fig. 3).
Histological examination of biopsy specimens from the left pleura showing lymphoplasmacytic infiltration. (A): Hematoxylin-eosin (H&E) staining, x 40; (B): Immunohistochemical staining for immunoglobulin (Ig)G4, x 40; (C): immunohistochemical staining for IgG, x 40.
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The histological analysis revealed dense lymphocytic infiltrates and mild eosinophilic infiltrates with no malignancy or granuloma (Fig. 4A). IgG4 of 724 mg/dL, and serum immunoglobulin E level of 5309 mg/dL. Immunohistochemical staining revealed 286 IgG4-positive plasma cells/high-power field in the pleural membranes (Fig. 4B); the ratio of IgG4-to IgG-positive plasma cells (IgG4/IgG) was 46% (Fig. 4B and C), which met the diagnostic criteria for IgG4-RD.