Fibrosing Mediastinitis

Fibrosing mediastinitis
- rare condition characterized by
- docal or
- diffuse fibrosis in the mediastinum

Fibrosing mediastinitis. High-power photomicrograph (original magnification, ×100; hematoxylin-eosin stain) demonstrates paucicellular, eosinophilic mature collagen, findings typical of fibrosing mediastinitis.
Rossi et al Radiographics
https://pubs.rsna.org/doi/10.1148/radiographics.21.3.g01ma17737
Rossi et al Radiographics

Histoplasmosis

Fibrosing mediastinitis due to histoplasmosis in a 36-year-old woman with dyspnea.
Contrast-enhanced CT scan (mediastinal window) shows a right hilar and subcarinal soft-tissue mass obstructing the right pulmonary artery (R) and superior pulmonary vein (arrowhead). More caudal images (not shown) demonstrated obstruction of the inferior pulmonary vein. Note punctate subcarinal calcification (arrow). A = aorta, S = superior vena cava.
Rossi et al Radiographics

CT scan (lung window) shows marked thickening of interlobular septa (arrows) in the right lung.
Rossi et al Radiographics

Sclerosing diffuse large B-cell lymphoma
High-power photomicrograph (original magnification, ×400) of a specimen stained with immunohistochemistry for CD20 (B-cell marker) shows positive cytoplasmic staining.
Rossi et al Radiographics

CT Appearance

Fibrosing mediastinitis
Radiopaedia
Case courtesy of Darel E Heitkamp, Radiopaedia.org, rID: 13520

Encasement of Structures
Bronchus

CT scan (lung window) shows an outpouching (arrowhead) of the anterior esophageal lumen adjacent to the stent that was confirmed to represent a bronchoesophageal fistula at a barium swallow examination (not shown). Note lingular consolidation, which most likely represents pneumonia. The patient subsequently underwent esophagectomy and anterior gastric interposition.
Rossi et al Radiographics

SVC

Superior vena cava syndrome due to fibrosing mediastinitis treated with balloon dilation and endovascular stent placement.
Contrast material-enhanced CT scan (mediastinal window) shows the infiltrating soft-tissue mass (solid arrows) with dense calcification in the right paratracheal region. Note obstruction of the superior vena cava, enhancement of multiple mediastinal collateral veins (arrowheads), and the densely calcified pulmonary nodule (open arrow).
Rossi et al Radiographics

Frontal superior vena cavagram shows a balloon-tipped catheter traversing a distal stenosis (arrows) of the superior vena cava. Note the mediastinal collateral veins (arrowheads). The patient underwent balloon dilation of the superior vena cava stenosis followed by placement of a metallic mesh stent.
Rossi et al Radiographics

Pulmonary Arteries and Veins

Frontal pulmonary arteriogram shows mild, smooth narrowing of the right pulmonary artery (P) and marked narrowing of the truncus anterior (arrows) and right interlobar pulmonary artery (arrowhead).
a metallic mesh stent.
Rossi et al Radiographics

Idiopathic fibrosing mediastinitis in a 30-year-old man with superior vena cava syndrome.
Contrast-enhanced CT scan (mediastinal window) obtained at a more caudal level shows encasement and narrowing of the right superior pulmonary vein (arrowheads).
a metallic mesh stent.
Rossi et al Radiographics

Idiopathic fibrosing mediastinitis in a 30-year-old man with superior vena cava syndrome.
Frontal pulmonary arteriogram shows smooth long-segment narrowing (arrows) of the right main pulmonary artery (M).
a metallic mesh stent.
Rossi et al Radiographics

Aorta

Idiopathic fibrosing mediastinitis in a 43-year-old woman with chronic cough and dyspnea. CT scan (mediastinal window) shows a soft-tissue attenuation mass diffusely infiltrating the middle and posterior mediastinum, encasing the descending aorta (a), and extending into both pleural spaces. Note extensive calcification within the pleura.
Rossi et al Radiographics

Esophagus

Idiopathic fibrosing mediastinitis in a 27-year-old woman with dysphagia and Riedel thyroiditis. Oblique barium esophagogram shows narrowing (arrows) and mucosal irregularity of the distal third of the esophagus. Note a superior esophageal diverticulum (D).
a metallic mesh stent.
Rossi et al Radiographics

Cause
- idiopathic:
- ? IgG4-related disease 17
- ? abnormal immune response to a
Infection
- - fungal
    - Histoplasma capsulatum infection (histoplasmosis)
      - localised pattern
  - bacterial infection
    - TB
Inflammatory Disease
- - - sarcoidosis
    - radiation therapy
Malignancy
- - - intrathoracic malignancy
Metabolic
- - - drugs: e.g. methysergide therapy 8

Associations
- - - Reidel thyroiditis
    - rheumatoid arthritis (RA)
    - systemic lupus erythematosus (SLE) 7
    - Behçet disease
    - retroperitoneal fibrosis
- results
  - excessive growth of fibrous tissue in the mediastinum,
    - - focal: ~80%
      - diffuse: ~20%
Clinical
- Symptoms of fibrosing mediastinitis can include
  - chest pain,
  - cough,
  - compression of the
    - - superior vena cava,
      - pulmonary veins or arteries,
      - central airways, or
      - esophagus
  - resulting in
    - shortness of breath, and
    - difficulty swallowing.
    - obstruction or
Diagnosis
- CT
  - Mediastinum
    - diffuse
    - focal
    - middle mediastinum
    - mediastinal mass
    - hilar mass
      - loss of fat planes
      - encasement of structures
        
        trachea
        
        arteries
        
        veins
        
        bronchial arteries due to vascular compromise
      - calcifications of the
        
        mass or associated
        
        lymph nodes:
        
        histoplasmosis
- Parenchymal changes secondary to
  - compression of
    - veins or lymphatics
      - prominent interstitial pattern
      - crazy paving secondary lymphatic or venous obstruction

- MRI scans, and
- biopsy

soft-tissue attenuation which obliterates normal mediastinal fat planes and encases or invades adjacent structures: diffuse form

MRI
- Fibrous tissue with inflammation and therefore
  - T1: dark
    - isointense to muscle
    - heterogeneous
  - T2: variable with both
    - dark
    - light intensities
    - T1 C+ (Gd):
      - heterogeneous enhancement
Treatment and prognosis
- slowly progressive
- unpredictable course, with both
  - spontaneous remission or
  - exacerbation

It usually tends to . There are three possible avenues for treatment: systemic antifungal or corticosteroid treatment, surgical resection, and local therapy for complications.

Treatment
- limited
- Antifungalsm
- Steroids (diffuse disease more responsive)
- managing symptoms and
  - preventing complications,
    - medication to reduce inflammation and pain,
    - interventions to
      - relieve compression

Links and References

Radiographics