Abstract Introduction IgG4-related disease (IgG4-RD) is a systemic fibroinflammatory disorder characterized by tumefactive lesions, dense lymphoplasmacytic infiltrates rich in IgG4-positive plasma cells, storiform fibrosis, and frequently elevated serum IgG4. We report a case of IgG4-RD presenting predominantly with pulmonary involvement, successfully treated with rituximab. Case Presentation A 57-year-old man, ex-smoker (20 pack-years, quit at 37) with colon carcinoma in situ, presented with two months of nonproductive cough and intermittent epigastric pain. He subsequently developed unintentional weight loss (9 kg), polyarthralgia, dry mouth, low-grade fever, and exertional dyspnea. While abdominal CT was performed to exclude intra-abdominal malignancy, it incidentally demonstrated a 3.38 cm, peribronchial, roughly circular consolidation with irregular border in the RLL. Chest CT revealed additional lesions in the RUL, RLL, and LUL, some with halo signs and peri-lesional cysts. Initial CT-guided and transbronchial biopsies showed chronic inflammation; bronchial washing cultures were negative. Labs revealed elevated CRP (20.36 mg/dL), ESR (90 mm/hr), ferritin (921.68 ng/mL), and serum IgG4 (383 mg/dL), with negative autoimmune serologies. Prednisolone 10 mg/day and azathioprine 50 mg/day were initiated three months after presentation. Despite partial improvement in inflammatory markers, symptoms and lesions persisted. At month five, VATS wedge resection of the RUL confirmed IgG4-RD, showing dense lymphoplasmacytic infiltrates, 40% IgG4-positive plasma cells, and storiform fibrosis. Prednisolone and azathioprine doses were increased, but disease recurred after tapering. Hydroxychloroquine, methotrexate, and mycophenolate mofetil were added without effect. Rituximab (500 mg IV on days 1 and 15, repeated six months later) resulted in symptomatic improvement, normalization of inflammatory markers, and partial radiographic resolution. Discussion Pulmonary involvement occurs in 30-40% of IgG4-RD, though isolated disease is rare. Manifestations include nodules, consolidation, interstitial opacities, and bronchial wall thickening. Corticosteroids are first-line therapy, but refractory cases may require steroid-sparing agents or B-cell-depleting therapy such as rituximab. Conclusion This case illustrates pulmonary-predominant IgG4-RD refractory to conventional therapy and successfully managed with rituximab, emphasizing the need to consider IgG4-RD in patients with persistent pulmonary lesions and elevated inflammatory markers. This abstract is funded by: None
Chang et al. (Fri,) studied this question.