Thursday 26 August 2010
Sclerosing mediastinitis consists of a fibroinflammatory mass within the mediastinum that often secondarily obstructs the trachea and bronchi, esophagus, and veins. It mimics malignancy both clinically and radiographically.
The etiology of sclerosing mediastinitis is varied. Major causes have included infection (Histoplasma capsulatum, other fungi, tuberculosis), sarcoidosis, and trauma and may also be idiopathic.
Recent reports suggest that some idiopathic cases may be a manifestation of IgG4-related sclerosing disease.
Inoue et al. reported a case of sclerosing mediastinitis accompanied by high serum levels of IgG4. The patient was a 56-year-old woman with exertional dyspnea and a diffuse mass in the posterior mediastinum on CT scan that entrapped the esophagus, bronchi, and azygos vein. A biopsy of the mass showed numerous IgG4-positive plasma cells. Both the mass and the patient’s symptoms resolved after treatment with steroids.
Zen et al10 reported a similar case involving a 52-year-old man with a combination of retroperitoneal and mediastinal fibrosis. Like the case reported by Inoue et al, serum levels of IgG4 were elevated and a biopsy from the retroperitoneal mass showed numerous IgG4-positive plasma cells. Both retroperitoneal fibrosis and mediastinal fibrosis responded readily to treatment with steroids.
In both cases, mediastinal fibrosis occurred in the absence of autoimmune pancreatitis. I recently observed a similar case involving a 78-year-old man with a superior mediastinal mass encasing the left subclavian artery (Figure 1, h through j). The observations suggest that idiopathic cases of sclerosing mediastinitis may sometimes be a manifestation of IgG4-related sclerosing disease.
Inoue, M. , N. Nose , H. Nishikawa , M. Takahashi , Y. Zen , and M. Kawaguchi . Successful treatment of sclerosing mediastinitis with a high serum IgG4 level. Gen Thorac Cardiovasc Surg 2007. 55 (10):431–433.
Zen, Y. , A. Sawazaki , S. Miyayama , K. Notsumata , N. Tanaka , and Y. Nakanuma . A case of retroperitoneal and mediastinal fibrosis exhibiting elevated levels of IgG4 in the absence of sclerosing pancreatitis (autoimmune pancreatitis). Hum Pathol 2006. 37 (2):239–243.