Immunoglobulin G4-related disease mimicking lymphoma in a Chinese patient.

Immunoglobulin G4-related disease (IgG4-RD) is a systemic disorder characterized by multiorgan fibrosis with IgG4-producing plasma cells, increased IgG4 serum concentration, and responsiveness to steroid therapy. IgG4-RD tends to form tumefactive lesions. As a result, patients are often suspected of having a malignancy such as lymphoma. In this article, a patient with IgG4-RD and the deep vein thrombosis who was initially suspected of lymphoma is reported. The 63-year-old man presented with painless salivary swelling and multi-lymphadenopathy, progressively swelling and pain in the left leg. Salivary biopsy showed IgG4+ plasma cells >50 per high-power field and IgG4+/IgG+ plasma cell ratio >40 %. The serum IgG4 level was 4.28 g/L (range 0.03-2.01 mg/dL). Ultrasonography showed that the inferior vena cava was partially occluded, and thrombosis in the left iliac vein. Computed tomography scan revealed plaque-like tissue surrounding the inferior vena cava and abdominal aortic, which is typical for the diagnosis of retroperitoneal fibrosis. The patient was effectively treated with corticosteroids, interventional therapy, and anticoagulant therapy which resulted in a reduction in the swelling of the lymph nodes and left leg. Patient with IgG4-RD and deep vein thrombosis is rare and could be misdiagnosed easily as malignant disease. Accurate diagnosis is critical for disease management.