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

Abstract

Acute or chronic non-neoplastic diffuse mediastinal diseases have multiple causes, degrees of severity, and a wide range of management. Some situations require emergency care while others do not need specific treatment. Although the diagnosis may be suspected on chest X-ray, it is mainly based on CT. A delayed recognition is not uncommonly observed. Some findings may prompt the radiologist to look for specific associated injuries or lesions. This pictorial review will successively describe the various non-neoplastic causes of diffuse mediastinal diseases with their typical findings and major differentials. First, pneumomediastinum that can be provoked by extra- or intra-thoracic triggers requires the knowledge of patient’s history or recent occurrences. Absence of any usual etiological factor should raise suspicion of cocaine inhalation in young individuals. Next, acute mediastinitis may be related to post-operative complications, esophageal perforation, or contiguous spread of odontogenic or retropharyngeal infections. The former diagnosis is not an easy task in the early stage, owing to the similarities of imaging findings with those of normal post-operative appearance during the first 2–3 weeks. Finally, fibrosing mediastinitis that is linked to an excessive fibrotic reaction in the mediastinum with variable compromise of mediastinal structures, in particular vascular and airway ones. Differential diagnosis includes tumoral and inflammatory infiltrations of the mediastinum.

Chest X-ray features facilitate screening for pulmonary hypertension caused by fibrosing mediastinitis

“…Previously, the imaging features of the patients with FM have been reported to include mediastinal widening, hilar enlargement, and right side parabronchial signs. 12,16 However, in this study, there were no significant differences in these parameters between the PH-FM and PH-non-FM patients. This could be ascribed to the greater incidence of hypoxia and pulmonary parenchymal abnormalities in the non-FM patients.…”

“…However, atelectasis, consolidation, nodules, calcification, interlobular septal thickening, grid-like lesions, and pleural effusion were more prevalent to patients with PH-FM, and these observations were related to the pathological process of FM. 8,12,16 The enlargements in the main pulmonary artery and RDPA were the imaging features of PH, 10 and there is no difference in these features between the two groups of patients.…”

Idiopathic fibrosing mediastinitis with esophageal varices: A case report

“…However, there may be a distinct form of FM that is idiopathic [ 6 ]. The disease causes constriction of systemic veins, pulmonary arteries and veins, the airways, and/or the esophagus, with symptoms related to the extent and location of fibrosis [ 7 ].…”

“…The most common form of FM is the focal pattern or granulomatous subtype, which is more frequently seen in histoplasmosis and less in tuberculosis or other fungal or inflammatory diseases. It usually manifests as a localized, calcified mass in the paratracheal or subcarinal regions of the mediastinum, which is mainly responsible for an SVC obstruction [ 7 ].…”

“…It may be idiopathic, occur in association with autoimmune disorders, or result from prior radiation exposure. The non-granulomatous subtype presents as rarely calcified, diffusely infiltrated soft tissue with heterogeneous contrast enhancement, and possible bronchial artery hypertrophy, unilateral pulmonary oedema, loss of lung volume, and chronic post-obstructive pneumonitis [ 7 ].…”