Idiopathic Fibrous Mediastinitis

Abstract

Fibrous mediastinitis has been recognized as a disease entity for more than half a century. At the turn of the century and in subsequent decades it paralleled then prevalent and notoriously sclerogenic tuberculous and syphilitic infections. In recent decades, similar exuberant fibrous processes are observed, but some are of rather nebulous origin and are therefore considered idiopathic. Obstruction of the superior vena cava is the hallmark of this disease. It has been estimated that 10 to 23 per cent of such obstructions are due to fibrous mediastinitis. Of 20 Mayo Clinic patients with the so-called idiopathic variety diagnosed on the basis of surgical exploration or necropsy, 12 had either complete or partial superior vena caval obstruction, four had involvement of the tracheobronchial tree, two had esophageal obstruction, one died of stenosis of the pulmonary vein, and one had fibrosis as an incidental finding at necropsy. Grossly the process usually assumes the form of a diffuse and adherent woody mass of fibrosis, but occasionally a circumscribed localized type is also encountered, which can be removed surgically with relative ease. Histologically, nothing more is seen than an inflammatory mass of fibrous tissue in various stages of maturity, ranging from young fibroblastic tissue intermixed with inflammatory cells to ancient and hyalinized collagen. The process is most probably an exaggerated reparative fibroblastic reaction secondary to mediastinal adenopathy or to direct spread of inflammation from infections of the upper and lower parts of the respiratory tract. Less commonly it may result from hemorrhage, from rheumatic fever or unknown acute mediastinitis. All of this appears to take place in a patient with great proclivity to form excessive fibrous tissue such as may be observed in other phases of surgery in the form of exuberant scars and adhesions. Surgical treatment is concerned mainly with superior vena caval obstruction, the effective relief of which still awaits further perfecting of grafting material and procedures. The over-all prognosis is good, as the disease progresses very slowly and the complication results usually from the slow contraction of scar tissue. Exception is made in stenosis of the pulmonary vein: all six patients so affected died of this complication.