What is fibrosing mediastinitis?

The mediastinum is the area between your lungs. Fibrosing mediastinitis (FM) is characterised by fibrosis of the mediastinum which means inflammation has caused tissue to harden and overgrow.¹ More positive news is that FM is benign, meaning the growth causing inflammation is not cancerous.²

FM is progressive, which is understandably difficult to hear. This means that it is expected for the conditions to become worse and will likely further complicate your quality of life. Over time, the excessive growth in fibrous tissue means benign tumours will eventually begin to compress vital structures within the mediastinum. These structures include:³

• Oesophagus (food tube)
• Heart
• Thymus (helps the immune system)
• Trachea (windpipe)
• Critical blood vessels around the heart

This has challenging complications which involve disruption to blood flow and breathing.¹

The cause of FM is not exactly understood, but most cases of FM are thought to be caused by a heightened immune response when exposed to a fungus called Histoplasma capsulatum which leads to histoplasmosis. The route of infection is through inhalation and the fungus is found in soil primarily in the central and eastern United States.¹

Autoimmune diseases have been associated with those who suffer from FM. The following autoimmune disorders listed have been reported in patients suffering from FM:^1,4

• Behcet disease
• Vasculitis
• Rheumatic fever

FM can also be associated with other disorders, including sclerosing cholangitis, retroperitoneal fibrosis and Riedel thyroiditis.

What is the lymphatic system?

FM causes complications in the lymphatic system, so it is important to understand the lymphatic system's role in managing the complications you may find yourself dealing with when suffering from FM.

The lymphatic system is made up of water fluid, which protects your body from the invasion of pathogens. In this case, pathogens are going to represent viruses and bacteria. The lymphatic system surrounds almost all organs within the body, and it contains white blood cells, which are responsible for removing those harmful pathogens.

Within the lymphatic system, there are tiny organs called lymph nodes. These are responsible for trapping the pathogens that have been detected. The mediastinum, where FM affects, is the most critical area for lymphatic drainage, so inflammation here has multiple different complications.⁵

What does fibrosing mediastinitis look like for you?

The initial infection

Since the cause of FM is not fully understood yet, we do know that an infection causing a cluster of immune cells is a pathway leading to FM. The example that you will most likely come across is histoplasmosis. After an infection, our body will begin what is called an immune response. This means that inflammatory cells will populate the infection site in an attempt to stop the infection from spreading and becoming worse.⁶ You will find that, in most cases, this will lead to the healing of the tissue that was inflamed; however, in FM, the tissue does not heal correctly, which leads to a build-up of collagen and excessive production of fibroblasts. Fibroblasts are the main cells that makes up our bodily tissue.⁷ This means the mediastinum tissue will become thick and scarred.

Complications on surrounding mediastinal structures

Over time, the progressive fibrosis within the mediastinum will negatively impact the surrounding structures. This includes tissue growth and compression on the airways, blood vessels of the heart and even nerve damage. There are signs that will allow you to manage this challenging condition. Symptoms are as follows:

• Blood vessel compression can lead to superior vena cava syndrome, which has signs such as facial swelling, cyanosis and enlargement of the neck or chest veins.⁸ You need to be aware of further complications from this, which will most likely be high blood pressure (hypertension)⁹
• Airway compression can lead to breathing difficulty (dyspnea), a cough and recurrent chest infections. If the compression is present around the oesophagus (food tube), you may experience dysphagia, which is when you struggle to swallow¹⁰
• Nerve damage can occur from excessive tissue compression, which has slightly more challenging complications.¹¹ This includes vocal cord paralysis and sometimes paralysis of the diaphragm (a muscle involved in breathing). It may come as a slight relief that nerve damage is more uncommon compared to the other symptoms presented to you here
• Impaired lymphatic drainage can have significant and wide-ranging implications, as the lymphatic system plays a crucial role in maintaining fluid balance, immune function, and the removal of waste products from tissues

Lymphatic complications in fibrosing mediastinitis

Lymphedema

This is another word for chronic swelling which can occur all over the body. Similarly to the complications stated so far, it is not uncommon for your lymph nodes and vessels to become compressed.¹¹ Over time lymphedema may lead to increased infection and further thickening of your skin. Chronic lymphedema may also lead to venous insufficiency, where your veins will begin to struggle to return the blood to your heart which may result in further swelling and discomfort.¹²

Since this is undoubtedly greatly uncomfortable, there are added impacts of lymphedema. Over time you are going to become more frustrated over the discomfort and change of appearance. This may also reduce your mobility,¹³ so it is essential that you are able to manage the symptoms from an early stage. You also have the help of therapy which could allow you to have as much of a positive and effective outlook on FM as possible. 

Increased risk of infections

Since the lymphatic system acts like your blood flow, lymph fluid is, therefore, always flowing. A blockage from fibrosis can result in the lymph fluid becoming stagnant,¹⁴ creating the perfect environment where bacteria can grow. As a result, you are at a greater risk of recurrent infection.¹⁵ Common infections associated with the lymphatic system are cellulitis and lymphangitis.

Preparing you for what this means regarding your long-term effects is important. With the immune system closely linked to the lymphatic system, your body will see a dramatic toll on the ability to fight off infections. Blockages in the lymphatic system drainage mean you may experience a delay in starting an immune response.¹⁶ It would therefore be expected for you to not only be ill more often but for longer periods. Consequently, I want to repeat that psychological effects are likely to come with this since it is understandably challenging to deal with such impacts on your quality of life.

Lack of lymph drainage,¹⁴ would also open the possibility of a build-up in waste products. This would result in an abundance of waste within your bodily tissue, and so, regrettably, this may lead to tissue damage and dysfunction.¹⁷

Knock-on effects on other body systems

• The lymphatic system is involved in the absorption of fats and fat-soluble vitamins from the digestive system. Impairment can affect your ability to absorb nutrients and may result in nutritional deficiencies¹⁷
• Cardiovascular implications (involving the heart and blood vessels) can evolve since the lymphatic system maintains a balance of fluid.¹⁴ between your blood and bodily tissues. If the lymphatic drainage is disturbed, certain conditions, such as heart failure, can develop

Summary

Let’s recap

FM is a rare condition involving excessive scarring and tissue thickening after an infection in the mediastinum, which is the area between the lungs. There is great difficulty coming to terms with the fact that FM is progressive, meaning the symptoms and complications associated with FM are going to get worse. This will result in greater impacts on quality of life, so it is important to manage the symptoms and prepare for them as much as possible.

In most cases, infection is from a fungus called Histoplasma capsulatum, leading to histoplasmosis. You can also suffer from autoimmune disorders like Behcet disease and vasculitis, which can also trigger FM. Most of your most challenging symptoms will occur around your chest area, such as difficulty breathing and discomfort from compression of vital structures like the windpipe and major heart blood vessels. Less common symptoms to consider include nerve damage, such as vocal cord paralysis.

More importantly, the lymphatic system will become greatly disrupted if you do not manage your symptoms effectively, which can have several knockoff effects, such as further risk of infection and chronic swelling (lymphedema). This may further prevent your body from effectively draining lymph. Early intervention and therapy are crucial for managing symptoms and maintaining a positive outlook.