Fibrosing mediastinitis (FM), also known as mediastinal fibrosis or sclerosing mediastinitis
, is a rare disorder characterized by proliferation of fibrous tissue within the mediastinum.
On the resection specimen, sclerosing mediastinitis
will usually appear quite infiltrative and show only inflammatory and sclerotic fibrocollagenous tissue.
Masses situated in all mediastinal compartments are lymphoma and sclerosing mediastinitis
Compartmental distribution of mediastinal lesions Compartment No of Cases Percentage Anterior Mediastinum 26 52 Middle Mediastinum 9 18 Posterior Mediastinum 15 30 Anterior Mediastinal Lesions distribution NO of CASES Percentage Thymic masses 7 26.
1,3,5) Retroperitoneal fibrosis, sclerosing cholangitis, Riedel thyroiditis, and sclerosing mediastinitis
are all associated with orbital pseudotumors, and they provide a basis for a unifying autoimmune or genetic cause.
The spectrum of mass-forming IgG4related sclerosing disease includes fibroinflammatory masses (some of which resemble pulmonary hyalinizing granuloma, see below); inflammatory pseudotumor, plasma cell granuloma type; and sclerosing mediastinitis
8) Some cases of sclerosing mediastinitis, which may secondarily affect the lung, have also been reported as a manifestation of IgG4 systemic sclerosing disease.
Sclerosing mediastinitis consists of a fibroinflammatory mass within the mediastinum that often secondarily obstructs the trachea and bronchi, esophagus, and veins.
Inoue et al (9) reported a case of sclerosing mediastinitis accompanied by high serum levels of IgG4.
Sclerosing mediastinitis and hyalinizing granuloma share similar histologic features and are both thought to be immunologically derived.
Sclerosing mediastinitis is a rare condition thought to result from many etiologies, an abnormal immunologic response to histoplasmosis being the most prominent one in the United States (Table 2).
Radiologically, sclerosing mediastinitis is divided between 2 types: focal, the most common, and diffuse.
3] It has also been described as part of multifocal or systemic fibrosclerosis, a disease spectrum that also includes retroperitoneal fibrosis, sclerosing mediastinitis
, Riedel thyroiditis, and orbital pseudotumor.