A Case of IgG4-Related Lung Disease Presenting as Interstitial Lung Disease

Abstract

Intrathoracic involvement of immunoglobulin G4 (IgG4)-related disease has recently been reported. However, a subset of the disease presenting as interstitial lung disease is rare. Here, we report a case of a 35-year-old man with IgG4-related lung disease with manifestations similar to those of interstitial lung disease. Chest computed tomography showed diffuse ground glass opacities and rapidly progressive pleural and subpleural fibrosis in both upper lobes. Histological findings showed diffuse interstitial lymphoplasmacytic infiltration with an increased number of IgG4-positive plasma cells. Serum levels of IgG and IgG4 were also increased. The patient was diagnosed with IgG4-related lung disease, treated with anti-inflammatory agents, and showed improvement. Lung involvement of IgG4-related disease can present as interstitial lung disease and, therefore, should be differentiated when evaluating interstitial lung disease.

Keywords: IgG4; Lung Diseases; Lung Diseases, Interstitial.

Figure 1

Chest radiography showed bilateral subpleural irregularities, ill-defined ground glass opacities, and reticular opacities in both upper lung fields with volume loss of both upper lobes.

Figure 2

Chest computed tomography demonstrated subpleural fibrosis in both upper lobes, diffuse ground glass opacities and bronchiectasis in the left upper lobe (A), and focal ground glass opacities in the superior segment of the left lower lobe (B), and the lateral segment of the right middle lobe (C).

Figure 3

Histological examination showed diffuse cellular interstitial infiltration with mild peribronchiolar lymphoid follicles and pleural and subpleural fibrosis (A, B) (A, H&E stain, ×12.5; B, H&E stain, ×40). Infiltrated cells were mostly lymphocytes and plasma cells (C, H&E stain, ×200). Immunohistochemical staining for IgG4 revealed many IgG4-positive plasma cells which measured 11 to 12 cells/high power field on average (D, ×200).

Figure 4

After anti-inflammatory therapy with prednisolone and azathioprine for 3 months, chest radiography showed improvement of reticular opacities and ground glass opacities in the left upper lung field. There was no significant interval change of subpleural fibrosis in both upper lung fields.