Primary bronchopulmonary amyloidosis

Primary bronchopulmonary amyloidosis is a primary disease characterized by the deposition of amyloid in the lung parenchyma, vascular walls, respiratory tract mucosa, pleura, and mediastinal lymph nodes.

The cause, pathogenesis of amyloidosis and its classification are described in the article “ What causes amyloidosis? ”

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Pathomorphology of primary bronchopulmonary amyloidosis

The following clinical forms of primary amyloidosis of the bronchopulmonary system are distinguished:

• localized amyloidosis of the trachea, bronchi;
• diffuse amyloidosis of the trachea, bronchi;
• localized (solitary) pulmonary amyloidosis;
• diffuse alveolar-septal amyloidosis;
• pleural amyloidosis;
• amyloidosis of mediastinal lymph nodes;
• combined forms.

Amyloid deposits in the trachea and bronchi appear as multiple grayish-white smooth nodules up to 1 cm in diameter, and the entire wall of the bronchus can be infiltrated, leading to its narrowing.

In the solitary form of pulmonary amyloidosis, there are one or more foci of amyloid deposits (pseudotumor formations). This form is observed very rarely. Diffuse pulmonary amyloidosis is much more common. It is characterized by the deposition of amyloid in the interalveolar septa, around capillaries, arteries, veins, resulting in their narrowing and desolation with the subsequent development of pulmonary hypertension and the formation of chronic pulmonary heart disease. Amyloid deposits in the bronchopulmonary system are detected using histochemical studies.

Symptoms of primary bronchopulmonary amyloidosis

Localized amyloidosis of the larynx, trachea and bronchi has the following characteristic clinical manifestations:

• a hacking, dry, often painful cough;
• often hemoptysis;
• hoarseness of voice;
• labored, wheezing breathing;
• atelectasis of the corresponding area of the lung due to bronchial obstruction. Clinically, this is manifested by dullness of percussion sound with the absence or sharp weakening of vesicular breathing, as well as relapses of inflammation in the atelectatic area of the lung; this is accompanied by a cough with the separation of purulent sputum;
• wheezing (due to narrowing of the affected bronchus).

Localized (solitary) amyloid deposits in the lung parenchyma do not manifest themselves clinically (with large deposits, dullness of percussion sound is possible) and are diagnosed only radiologically.

Diffuse pulmonary amyloidosis is accompanied by the following symptoms:

• cough, unproductive or with the separation of mucous sputum, with the addition of a secondary infection in the bronchi - mucopurulent sputum;
• slowly but steadily progressing shortness of breath, first with exertion, then at rest;
• recurrent hemoptysis, usually moderate in severity;
• chest pain that intensifies with breathing and coughing (if the pleura is involved in the pathological process);
• difficulty swallowing (with damage to the intrathoracic lymph nodes and compression of the esophagus);
• weakened vesicular breathing, a slight silent crepitation may be heard mainly in the lower parts of the lungs. In case of bronchial damage and development of bronchial obstruction, dry wheezing rales are heard;
• diffuse gray cyanosis (with the development of severe respiratory failure);
• muffled heart sounds, with the development of chronic pulmonary heart disease - emphasis of the second heart sound on the pulmonary artery;
• pain in the right hypochondrium and enlargement of the liver - observed with decompensated pulmonary heart disease.

Laboratory data

1. General blood analysis - no significant changes, sometimes an increase in ESR, thrombocytosis is determined. When infectious and inflammatory processes are added, leukocytosis appears with a shift in the leukocyte formula to the left.
2. General urine analysis - no deviations from the norm in most patients, sometimes slight proteinuria is noted.
3. Biochemical blood test - hypergammaglobulinemia, hypercholesterolemia are characteristic, an increase in the activity of aminotransferases, alkaline phosphatase is often noted, with decompensated pulmonary heart disease and an enlarged liver, an increase in the bilirubin level is possible.
4. Immunological studies often reveal a decrease in the number of T-suppressor lymphocytes, an increase in B-lymphocytes, immunoglobulins of the IgM and IgG classes, and the possible appearance of circulating immune complexes.

Instrumental research

1. X-ray examination of the lungs. Solitary amyloidosis of the lungs manifests itself as rounded darkenings with clear contours with a diameter of 1 to 5 cm. Calcium may be deposited in foci of solitary amyloidosis, which is accompanied by a more intense shadow in the focus of compaction.

Diffuse amyloidosis of the bronchi is characterized by an increase in the bronchial pattern due to the thickening of the bronchial walls. Diffuse amyloidosis of the lungs is manifested by an increase in the pulmonary pattern or diffuse small focal darkening.

In amyloidosis of the pleura, its thickening is observed; in amyloidosis of the intrathoracic lymph nodes, their enlargement is clearly visible, and they can sometimes become calcified.

2. Endoscopic examination of the trachea and bronchi reveals a characteristic picture: edematous mucous membrane with coarse folds (cobblestone appearance) with protruding yellowish papules. Biopsy of the mucous membrane allows for a more precise diagnosis of amyloidosis.
3. Study of the ventilation function of the lungs.

In amyloidosis of the trachea and bronchi, obstructive respiratory failure (reduced FEV1) develops, and in diffuse amyloidosis of the lungs, restrictive type (reduced VC) develops. Solitary amyloidosis of the lungs may not manifest itself in disorders of the ventilation function of the lungs.

4. ECG - with the development of pulmonary hypertension (with the diffuse form of pulmonary amyloidosis) and the formation of chronic pulmonary heart disease, signs of myocardial hypertrophy of the right atrium and right ventricle appear.
5. Examination of biopsies of the mucous membrane of the bronchi, trachea, and lungs.

Biopsy of the mucous membrane of the trachea, bronchi, open or transbronchial lung biopsy is a reliable method for verifying the diagnosis. Amyloidosis is characterized by a sharply positive staining with Congo red, and microscopy in polarized light reveals an amorphous substance with birefringent amyloid fibers of a greenish color.

The prognosis for primary bronchopulmonary amyloidosis is considered relatively favorable; life expectancy after diagnosis can be 30-40 years. The main complications are bronchopulmonary infectious and inflammatory diseases, respiratory failure, and chronic pulmonary heart disease.

Screening program for primary bronchopulmonary amyloidosis

1. General blood and urine tests.
2. Biochemical blood test: determination of total protein, protein fractions, cholesterol, triglycerides, aminotransferases, alkaline phosphatase, bilirubin.
3. Immunological studies: determination of the content of B- and T-lymphocytes, subpopulations of T-lymphocytes, immunoglobulins, circulating immune complexes.
4. X-ray of the lungs.
5. Fiberoptic bronchoscopy, tracheoscopy.
6. ECG.
7. Spirometry.
8. Examination of biopsies of the trachea, bronchi, and lungs.