Multimodality Imaging of Focal and Diffuse Fibrosing Mediastinitis

Abstract

Fibrosing mediastinitis is a rare benign but potentially life-threatening process that occurs because of proliferation of fibrotic tissue in the mediastinum. The focal subtype is more common and typically is associated with an abnormal immunologic response to Histoplasma capsulatum infection. Affected patients are typically young at presentation, but a wide age range has been reported, without a predilection for either sex. The diffuse form may be idiopathic or associated with autoimmunity, usually affects middle-aged and/or elderly patients, and is more common in men. For both subtypes, patients present with signs and symptoms related to obstruction or compression of vital mediastinal structures. The most common presenting signs and symptoms are cough, dyspnea, recurrent pneumonia, hemoptysis, and pleuritic chest pain. Patients with the diffuse subtype may have additional extrathoracic symptoms depending on the other organ systems involved. Because symptom severity is variable, treatment should be individualized with therapies tailored to alleviate compression of the affected mediastinal structures. Characteristic imaging features of fibrosing mediastinitis include infiltrative mediastinal soft tissue (with or without calcification) with compression or obstruction of mediastinal vascular structures and/or the aerodigestive tract. When identified in the appropriate clinical setting, these characteristic features allow the radiologist to suggest the diagnosis of fibrosing mediastinitis. Careful assessment is crucial at initial and follow-up imaging for exclusion of underlying malignancy, assessment of disease progression, identification of complications, and evaluation of treatment response.

Imaging features and differential diagnoses of non-neoplastic diffuse mediastinal diseases

“…Fibrosing mediastinitis (FM), also known as sclerosing mediastinitis, is a condition related to an abnormal immunologic reaction that results in the proliferation of fibro-inflammatory tissue in the mediastinum and/ or hila [12]. It leads to a variable constriction of systemic veins, pulmonary arteries and veins, the airways and/or the esophagus, with a morbidity related to location and extent of fibrosis.…”

“…It leads to a variable constriction of systemic veins, pulmonary arteries and veins, the airways and/or the esophagus, with a morbidity related to location and extent of fibrosis. The pleura, pericardium, and coronary arteries may also be involved [12].…”

“…The diffuse or non-granulomatous subtype accounts for about 10 to 20% of cases of fibrosing mediastinitis. It may be idiopathic or can originate in association with autoimmune disorders, methysergide exposure, or prior radiation exposure [12]. Fibrosing processes in other locations, such as retroperitoneal fibrosis, may also be encountered [12].…”

“…It may be idiopathic or can originate in association with autoimmune disorders, methysergide exposure, or prior radiation exposure [12]. Fibrosing processes in other locations, such as retroperitoneal fibrosis, may also be encountered [12]. This subtype, which affects multiple mediastinal compartments and which is sometimes diagnosed after considerable delay, manifests as diffusely infiltrated soft tissue, rarely calcified, with heterogeneous enhancement after intravenous administration of contrast material.…”

“…10) [13], and hemoptysis may occur due to hypertrophy of the systemic arteries. With regard to airway involvement, the trachea and the main, lobar, and/or segmental bronchi may be involved and are characterized by volume loss, chronic post-obstructive pneumonitis, endoluminal mucus plugs, or bronchiectasis [12]. Although surgical biopsies are more appropriate, the role of percutaneous CT-guided core tissue biopsies should be emphasized.…”