PMC5221465_01
Computed tomography scan. Solitary pulmonary nodule with an irregular margin.
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Computed tomography (CT) of the chest revealed a 3.1-cm pulmonary nodule with an irregular margin in the right middle lobe (Fig. 1).
Histolopathological and immunohistochemical examination of tissue sections. (A) Photomicrograph showing extensive lymphoplasmacytic infiltration with storiform fibrosis (haematoxylin and eosin staining, x100). (B) Photomicrograph showing infiltration of immunoglobulin (IgG)-positive plasma cells (IgG stain, x400). (C) Photomicrograph showing infiltration of immunoglobulin G4 (IgG4)-positive plasma cells (IgG4 stain, x400).
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Obliterative arteritis and phlebitis were also noted (Fig. 2A). Immunohistochemical staining indicated diffuse infiltration of IgG4-positive plasma cells, with an IgG4-positive/IgG-positive plasma cell ratio of 0.65 and an average number of 92 IgG4-positive plasma cells per high-power field (HPF) (Fig. 2B, C).