What is Fibrosing Mediastinitis?

Fibrosing Mediastinitis is a condition where scar tissue grows and develops in the space between the lungs due to an excessive immune response following an infection. This excessive scar tissue causes the blockage of bronchial tubes and compresses the blood vessels in the lungs. This condition may be life-threatening¹ and causes symptoms like breathing difficulties and pain.. Unfortunately, there is currently no cure for fibrosing mediastinitis. 

Fibrosing mediastinitis may be a fatal disease if left untreated.² It is therefore important to educate people who are at risk of developing fibrosing mediastinitis. This includes patients who have weaker immune systems, chronic obstructive pulmonary disease (COPD) and diabetes.³ Additionally, patients need to be educated on the treatment of FM before starting treatment. Key points to ensure that symptoms are minimised include medication use, side effects and when to seek further medical help.

This article will discuss the cause of fibrosing mediastinitis, its symptoms and the diagnosis of the disease. Finally, it will cover the types of treatment and management options. 

Cause

There are two main types of fibrosing mediastinitis, granulomatous and non-granulomatous. Although they can both be caused by an excessive immune reaction,⁵ they have slightly different triggers. Tuberculosis and histoplasmosis infections are known as triggers for granulomatous FM. Meanwhile, sudden autoimmune syndromes, medicines and radiation are known to be triggers for non-granulomatous FM.⁶

Symptoms

The symptoms of fibrosing mediastinitis ^3,7 can be present a few years before diagnosis, which includes: 

• Shortness of breath
• Fever
• Fibrosis or inflammation in other parts of the body
• Recurrent pulmonary infections and pneumonia
• Fatigue
• Coughing with blood 
• Chest pain 
• Pleural effusion
• Difficulty in swallowing
• Swelling of the face 

In particular, symptoms like chest pain, swelling in the face, pulmonary infections and pneumonia are usually caused by the critical narrowing of the vessels in the chest. This includes blood vessels like the superior vena cava, pulmonary arteries, and pulmonary veins. This causes superior vena cava (SVC) syndrome, where the vena cava is blocked and blood fails to return to the heart. Symptoms like cough, shortness of breath, coughing of blood, and pleural effusion are usually caused by obstruction of the airways.

Surgical management of fibrosing mediastinitis

Fibrosing mediastinitis does not have a standard treatment regimen. One of the known ways to relieve the condition includes surgical interventions. Surgeries to reduce symptomatic obstruction, bleeding and abnormal connection between the oesophagus and trachea are often performed. Depending on the symptoms and areas affected, the patient would undergo different types of surgeries. This includes procedures like mediastinal decompression, thoracotomy, airway reconstruction, peripheral artery bypass and more.⁸ Unfortunately, most surgical procedures have a relatively high operative mortality.⁹ Endobronchial stenting is also a common surgery performed on patients, it is mainly used to treat obstructed airways. Silicone stents are fitted to prevent tissue ingrowth and mucus accumulation in the lungs. In general, 5 out of 7 patients show improvements over time and are allowed the removal of the stents.¹⁰ Vascular stenting relieves the blockage in the superior vena cava, pulmonary artery and pulmonary vein.¹¹ In a case study where 40 patients with fibrosing mediastinitis are treated with vascular stenting, there is a success rate of 87%.¹¹

Medical management of fibrosing mediastinitis

One of the other possible methods of management may be medical treatments. However, compared to other methods, the effectiveness of medical management is not well-researched. Most of the data are based on small case reports.¹² There are reports of patients using antifungal and anti-inflammatory drugs like prednisone, tamoxifen, non-steroidal anti-inflammatory medication (indomethacin), and immunosuppressants (azathioprine and cyclosporin).⁵ These treatments tackle the exaggerated immune response by eliminating the infection source.¹³ In most cases, data shows that the majority of antifungals are largely ineffective. However, the drug itraconazole may still be used if the fibrosing mediastinitis is caused by a very recent infection. Steroids are also ineffective, but in certain rare cases, if fibrosing mediastinitis is caused by sarcoidosis, steroids may be an effective medication.¹⁴ Despite the lack of data on the effectiveness of drugs in treating fibrosing mediastinitis, the medical community needs to perform further research for possible drug solutions. In 2014, there was a study where rituximab was used on high-risk patients showing progressive and bilateral fibrosing mediastinitis. It was found that there was a decrease in inflammation, a decrease in symptoms and then a stabilisation of the disease in 15 patients.¹⁵ This discovery allowed rituximab to be administered as a treatment. 

Chest pain and other symptoms caused by the blocking and compression of blood vessels are treated with vasodilator drugs. This treats pulmonary hypertension. However, these drugs only treat specific symptoms and are known to be largely ineffective for fibrosing mediastinitis.¹⁶ Sometimes, antibodies can be used in cases when fluid retention occurs and causes complications such as pneumonia.⁴

Possibility of further research

As the knowledge on FM is currently limited, surgical methods are typically employed but they carry the cost of a high mortality rate. It is therefore important for more research into medical management of the disease. It is commonly known that there is an association of fibrosing mediastinitis with excessive immune response and bacteria Histoplasmosis. Possible drugs that target these immunological pathways could be developed to reduce the harm caused by this disease or possibly cure the disease. Other techniques such as CBT have been employed in the multi-targeted approach for managing FM.¹⁷

Additionally, there is a lack of data on the success rate of specific therapies for fibrosing mediastinitis as most patients are treated with a variety of therapeutic methods. Specific research done on individual methods may be beneficial for future treatments. As fibrosing mediastinitis is a rare disease, information on the long-term impact and survival of patients is still limited. It may be useful to set up a registry globally to optimise treatment and management methods to help these patients. 

Summary

Fibrosing mediastinitis is a rare, complicated and potentially life-threatening disease. Although there is currently no cure for the disease, it is important for patients not to give up hope and actively seek medical help to reduce the high mortality of the condition. Under proper management and treatment, it is likely that patients can live a relatively normal life with a good quality of life. There is room for the medical science community to focus on further research into the other possible management of FM.