What Is Transthyretin Amyloidosis?

Pulmonary amyloidosis is a group of clinical syndromes with different manifestations. The common feature is that extracellular amyloid deposits can invade various organs throughout the body. Bronchial-pulmonary amyloidosis can be part of the systemic primary amyloidosis Can also be secondary to chronic infectious diseases, familial or senile cardiac amyloidosis. Virchow called the disease amyloid for the first time in 1854, and it had the same dyeing properties as cellulose. It is metachromatic to crystal violet and can be stained purple by periodic acid-Schiff's (PAS) and is contaminated by Congo red.

Pulmonary amyloidosis

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Pulmonary amyloidosis is a group of clinical syndromes with different manifestations. The common feature is that extracellular amyloid deposits can invade various organs throughout the body. Bronchial-pulmonary amyloidosis can be part of the systemic primary amyloidosis Can also be secondary to chronic infectious diseases, familial or senile cardiac amyloidosis. Virchow called the disease amyloid for the first time in 1854, and it had the same dyeing properties as cellulose. It is metachromatic to crystal violet and can be stained purple by periodic acid-Schiff's (PAS) and is contaminated by Congo red.

The clinical manifestations of bronchopulmonary amyloidosis vary depending on the type of lesion and the affected organ. The following is classified by organ:

1. Laryngeal amyloidosis Laryngeal is the most common site of focal amyloidosis in the respiratory tract, and it is reported to account for about 75%. Laryngeal amyloidosis accounts for about 1% of benign laryngeal tumors, and more than 250 cases have been reported so far. The age of onset was 9 to 90 years (mean 48 years), and the male to female ratio was 1: 1. False vocal cords are the most commonly affected sites, and vocal cords and epiglottis are also frequently affected. The main symptom is hoarseness, which can be accompanied by bleeding and even cause a lethal upper respiratory tract

The cause of bronchopulmonary amyloidosis has not been fully elucidated. At present, it is thought that the focal tracheobronchial and pulmonary nodular amyloidosis, which accounts for the vast majority of the disease, are mainly of type A1, and the amyloid is mainly derived from immunoglobulin. Excessive deposition of amyloid in the bronchial lung may be related to the following factors:

1. An abnormal immune response occurs in bronchial-associated lymphoid tissue (BALT). Plasma cells from B lymphocytes show excessive monoclonal proliferation and mutation at the local level, generating excessive abnormal immunoglobulins and fragments that are structurally abnormal or exceed the body's ability to clear, Its degradation products form corresponding light chain fragments, which are deposited as amyloid in bronchial lung tissue. Some authors believe that macrophages are important sites for the conversion of immunoglobulin polypeptide precursors into amyloid structures, so plasma and macrophages often infiltrate the peripheral region of amyloidosis. Case reports of plasmacytoma and lymphoma complicated by amyloidosis support this theory, and clinical cases of plasmacytoma or lymphoma transformed into amyloid tumor (amyloidtumor) can be seen.

2. Due to inflammatory lesions in the lungs that increase vascular permeability, a large number of related protein precursors in circulating blood leak out from the blood vessels and deposit in the lungs. The aggregation and activation of plasma cells and phagocytic cells reflects the local inflammatory response. In some cases, bronchial pulmonary amyloid-containing serum monoclonal proteins support this theory. The production and deposition of amyloid appears to be regulated by T lymphocytes. Those with thymic hypoplasia who are congenital with low immune function are prone to amyloidosis. The time required to induce amyloidosis in thymic resected animals is significantly shorter than in normal animals. Local T-lymphocyte function is reduced and B-lymphocyte function is increased, and the pH value is reduced, which is conducive to amyloid deposition. Diffuse interstitial or alveolar septal amyloidosis can be derived from AL, AA protein, or thyroxin. As one of the manifestations of systemic amyloidosis, its etiology and pathogenesis may have the following:

3. Primary systemic amyloidosis or combined with multiple myeloma, malignant proliferation of bone marrow plasma cells (plasma cell disease), leading to subclinical or clinical multiple myeloma with AL fibril deposition in the lung.

4. Rarely secondary to chronic infection (tuberculosis, pyogenic osteomyelitis, leprosy), chronic inflammation (rheumatoid arthritis, Crohn's disease) or malignant tumors (Hodgkin's disease, kidney cancer). At this time, the serum acute response protein increased significantly, and the serum amyloid-associated (SAA) protein also continued to increase. AA protein is the degradation product of SAA protein, causing secondary or inflammation-related amyloidosis. It has been reported that AA protein mainly comes from irritated macrophages. It is present in trace amounts in normal human blood and has a molecular weight of about 8,500. It can be produced in large quantities in chronic infections and inflammatory diseases.

5. Family autosomal dominant hereditary and senile amyloidosis, amyloids mainly come from plasma thyroxin. Its structure is changed, and valine is replaced by methionine, so it has amyloidogenicity. 95% of thyroxine is derived from the liver and is mainly deposited in the central nervous system, myocardium, and interstitial lung. It is believed that diffuse pulmonary interstitial amyloidosis is mainly the result of leakage and deposition of circulating blood-related protein precursors from blood vessels, and is partly related to increased vascular permeability caused by inflammation. The leaked protein fragments are degraded and combined with the extracellular matrix to form amyloid fibrils. Monoclonal protein precursors can be found in patients' blood, and the lesion area can be free of plasma cell infiltration, etc., supporting this argument.

May have cough, wheezing, hemoptysis, hoarseness, and dyspnea, and purulent sputum after secondary infection.

Bronchial-pulmonary amyloidosis is a diverse group of clinical syndromes. It can be diagnosed according to fiberoptic bronchoscopy biopsy, open chest lung biopsy and other methods, so as to achieve the purpose of symptomatic treatment.

X-ray examination:

There are various manifestations, no obvious abnormal manifestations in the early stage, diffuse reticular nodular infiltration, miliary change or nodular type can be seen in the future, single or multiple circular shadows, and even mildly divided leaves can be With hilar or mediastinal lymph

Swelling may also have calcifications. Stenosis or obstructive pneumonia of the lung lobe or segment can be seen during bronchoconstriction.

Pulmonary function tests:

It can be in the normal range, or it can show restricted ventilation and reduced diffusion.

Biopsy:

Bronchial and lung tissues have amyloidosis, which can involve tissues and organs such as rectal mucosa, skin and subcutaneous fat or gums. Diagnosis is mainly based on transbronchial lung biopsy and thorax lung biopsy. Some patients are confirmed by autopsy after death.

(1) Those who are secondary to chronic infection should actively treat the infection;

(2) Try glucocorticoids;

(3) Other immunosuppressive agents can also be tried;

(4) those with limited lesions can be treated surgically;

(5) Microwave or laser treatment under endoscope.

The above treatments are only effective in some cases, and only refer to the relief of symptoms.