PMC6812137_01
Chest X-ray (a), computed tomography (CT) (b), and fluorodeoxyglucose positron emission tomography/CT (FDG-PET/CT) imaging (c) on admission. Chest X-ray showed left pleural effusion. Neck to pelvis CT imaging revealed swelling of the mediastinal and inguinal lymph nodes, as well as left pleural effusion with local pleural thickness (yellow arrows). FDG-PET/CT imaging showed FDG accumulation in the mediastinal lymph node, left inguinal lymph node, and left pleura (yellow arrows). . (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)
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Chest radiograph showed left pleural effusion (Fig. 1a). Neck to pelvis computed tomography (CT) revealed swelling of the mediastinal and inguinal lymph nodes as well as left pleural effusion with local pleural thickness (Fig. 1b). Fluorodeoxyglucose (FDG) positron emission tomography imaging showed accumulation of FDG in the mediastinal lymph node, left inguinal lymph node, and left pleura (Fig. 1c).
Histological findings of pleura and inguinal lymph node biopsy specimens. (a): Histological analysis of the pleura revealed dense lymphocyte and plasmacyte infiltration, accompanied by fibrosis [hematoxylin and eosin (H&E) staining, magnification: x10 (upper left), x400 (upper right)]. Immunohistochemical analysis showed a large number of IgG4+ cells (50 cells or more per high-power field) in the pleura; the IgG4+/IgG+ cell ratio exceeded 40% [immunohistochemical (IHC) staining, magnification: x200 (IgG staining; lower left, IgG4 staining; lower right)]. (b): Histological analysis of the inguinal lymph node revealed dense lymphocyte and plasmacyte infiltration, accompanied by fibrosis [H&E staining, magnification: x10 (upper left), x400 (upper right)]. Immunohistochemical analysis showed a large number of IgG4+ cells (50 cells or more per high-power field) in the inguinal lymph node; the IgG4+/IgG+ cell ratio exceeded 40% [IHC staining, magnification: x400 (IgG staining; lower left, IgG4 staining; lower right)].
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Therefore, we performed surgical biopsies of the pleura and left inguinal lymph node (Fig. 2).
(a): Clinical course after the patient was referred to our hospital. Serum IgG and IgG4 decreased without treatment. (b): Chest X-ray appearance at the time the patient was referred to our hospital (left), and after 4 years of observation (right). (c): Computed tomography imaging at the time the patient was referred to our hospital (i, ii), and after 4 years of observation (iii, iv). Mediastinal lymph nodes (i, iii) and left inguinal lymph nodes (ii, iv) are shown as yellow arrows.
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We then considered initiation of corticosteroid therapy; however, pleural effusion decreased without intervention, and dyspnea improved during the active surveillance period (Fig. 3a). The serum IgG/IgG4 levels gradually decreased (Fig. 3b) and the swelling of the mediastinum and inguinal lymph nodes also subsided (Fig. 3c).