What is Fibrosing Mediastinitis?

Fibrosis Mediastinitis (FM) is a very rare benign, inflammatory disease that is usually chronic.¹ It is characterised by the proliferation (rapidly increasing) of fibrous tissue (a dense supporting tissue that protects the organs) in the mediastinum (the large central part of the chest.² This condition can lead to severe compression and obstruction of the surrounding structures and organs, including the airways, major blood vessels, and the oesophagus. It can affect both children and adults, however, the presentation, diagnosis, management, and outcomes differ in the different age groups.

Risk factors of FM

Pediatric patients

In children, this condition is mostly due to certain infections and non-infectious diseases. Histoplasmosis is a fungal infection caused by Histoplasma capsulatum.³ It can cause a granulomatous reaction that progresses to FM. Tuberculosis (bacterial infection) affects the lungs and could spread to other organs. Although it is less common than Histoplasmosis, it can also contribute to FM. Autoimmune conditions like Systemic Erythematous Lupus (SLE) and juvenile idiopathic arthritis can present with FM. Certain genetic factors/conditions can predispose children to develop FM, though it is usually rare.

Adult patients

In adults, the aetiology of FM is varied. Similar to pediatric patients, histoplasmosis is common in endemic regions like the United States, Latin America, and Africa. Sarcoidosis, a systemic granulomatous disease, can affect the mediastinum, presenting with respiratory symptoms and enlarged lymph nodes. Tuberculosis is a major cause of FM in adults, particularly in patients with a history of heart disease. Autoimmune conditions like SLE and rheumatoid arthritis could also affect adults. A majority of the cases remain idiopathic with no apparent cause.

Symptoms of FM

Pediatric patients

The clinical presentation of FM in children can vary depending on the extent and location of fibrous tissue proliferation. Respiratory symptoms like chronic cough, wheezing, dyspnea (difficulty in breathing), and recurrent respiratory tract infection due to airway compression are the most common presentations.⁴ It can also cause chest pain, which could be associated with inflammation and compression of the mediastinal structures. Dysphagia ( swallowing difficulty) is another major clinical presentation due to esophageal compression, which could cause feeding difficulties in younger children. The child may fail to thrive due to chronic illness and nutritional challenges.

Adult patients

In adults, symptoms of FM are often related to the involvement of the mediastinal structures. The same presentation of respiratory symptoms along with chest pain and dysphagia could also be seen in adults. Patients may also have symptoms that could be associated with an underlying systemic condition, such as joint pain or skin rashes.

Diagnosis of FM 

Pediatric patients

Diagnosing FM in children requires a combination of clinical evaluation, imaging, and laboratory tests. Imaging studies like Chest X-rays and CT scans can help visualize the extent of the fibrosis and any other associated complications. A CT scan is more sensitive in detecting any masses or structural changes. Histoplasmosis could be confirmed with fungal cultures, serological testing, and histopathological examination of biopsy samples. A tuberculin skin test and interferon-gamma release assays (IGRAs) could be used to diagnose tuberculosis. When the cause is unclear, a biopsy of the mediastinal tissue could be performed to assess the exact cause.

Adult patients

The diagnostic approach for FM in adults involves similar steps. Chest X-rays and CT scans help investigate the extent of mediastinal involvement. MRI is used in cases where detailed imaging is required. Serological tests, cultures, and molecular assays are used to identify histoplasmosis and tuberculosis. Blood tests for autoimmune markers may be performed if suspicion of an autoimmune condition arises. A biopsy of mediastinal tissue confirms the presence of fibrous tissue proliferation.

Treatment and management of FM

Pediatric patients

In children, the treatment could depend on the etiological factors that caused FM. For infections, antifungal therapy and antimicrobial are used to treat conditions like Histoplasmosis and Tuberculosis, which are leading causes of FM. The treatment could also depend on the severity of the symptoms. Surgery may be considered in cases where severe obstructions impact the airway. Surgical removal or decompression is employed to help relieve the obstruction caused by the fibrous tissues. Corticosteroid therapy can be used as a supportive therapy to manage inflammation. In FM, regular monitoring is required to evaluate the patient on the progression of this disease and their response to treatment.

Adult patients

The management of FM in adults is similar to children with a combination of medical therapy and surgical intervention. Antifungal drugs for histoplasmosis, anti-tubercular drugs for tuberculosis, and antibiotics for any associated pneumonia conditions may be administered. These therapies help treat the underlying cause. Diuretic drugs can help improve fluid retention associated with FM. Corticosteroids can be used to reduce inflammation and immunosuppressive drugs could help control and treat autoimmune diseases. Surgeries could include resection, removing a part of the affected area of the lung, dilating the obstructed oesophagus, and stents to improve the airways.

Prognosis and outcome of FM 

Pediatric patients

The progression in children is usually rapid due to the smaller anatomical structure. The prognosis and outcomes in children suffering from FM depend on the underlying cause and the treatment strategy employed to treat it. Appropriate treatment with early diagnosis and timely intervention can massively improve the outcome of the symptomatic relief as well as improve the quality of life. Some patients may require ongoing therapy and may have long-term effects. 

Adult patients

The progression is chronic and slow with periods of resolution and exacerbation. The prognosis is similar in adults, depending on the underlying aetiology and response to treatment. Preventing complications with adequate monitoring, regular follow-up, and appropriate therapy may improve the outcome significantly.

Complications of FM 

Complications in Children

Airway obstruction is the most common complication because the excessive fibrous tissue can compress the airway and cause respiratory distress, recurrent infections, and difficulty breathing. Superior vena cava syndrome is another complication caused by the compression of the blood vessels leading to venous congestion. The significant complication in children is the reduction in growth. Chronic hypoxia (insufficient oxygen) and poor perfusion can affect growth in children. Heart complications like arrhythmias, heart failure, and pericarditis could arise. Oesophageal compression can lead to poor nutrition and aspiration pneumonia. Chronic obstruction and poor drainage can give rise to recurrent respiratory tract infections which would weaken the immune system. 

Complications in adults

Similar to children, airway obstruction, vascular compression, cardiac complications, and oesophageal compression could also present in adults. Chronic compression of the pulmonary arteries increases the pressure within the vessels, causing pulmonary hypertension and heart failure. The fibrosis and inflammation lead to chronic chest pain, debilitating the patient and their quality of life.. Reduction in the blood flow and stasis in compressed vessels can increase the risk of clot formation, leading to thromboembolic events such as pulmonary embolism.

Summary

Fibrosing mediastinitis is a benign, rare fibrous tissue proliferative condition that affects the mediastinum. It presents various scenarios, affecting both children and adults. The most common presentation is symptoms of respiratory distress and oesophageal compression. The causes are varied, with acquired infection more common in adults and congenital disorders in children. The diagnosis and treatment approach are similar with distinct challenges and management considerations for both pediatric and adult patients. The mainstay of therapy is to treat the underlying causes and symptomatic relief of the clinical manifestations between age groups. A thorough diagnostic workup and curated treatment are essential for effective management. Early intervention and ongoing monitoring play a vital role in improving outcomes and quality of life for patients with FM and preventing complications.