Alveolar microlithiasis of the lungs: causes, symptoms, diagnosis, treatment

Alveolar microlithiasis of the lung is a disease characterized by the deposition in the alveoli of substances consisting of mineral compounds and proteins. The disease is rare, occurs at any age, but mostly at the age of 20-40 years. Women are more often ill.

The cause, pathogenesis, pathomorphology of alveolar microlithiasis of the lungs

The cause and pathogenesis are unknown. In many patients the hereditary factor and the influence of occupational hazards are important.

The essence of the disease is hyperproduction and accumulation of protein in the alveoli, in which microcrystals of carbonate and calcium phosphate are deposited, which disrupts the processes of ventilation and perfusion, leads to the development of interstitial fibrosis and respiratory failure.

The characteristic pathomorphological signs of the disease are:

• increased density of lung tissue, especially lower lobes;
• detection in the alveoli and bronchioles of microconstrains with a diameter of 1-3 mm, containing calcium carbonate and phosphate, as well as microelements sodium, potassium, copper, zinc, magnesium; microliths have a concentric complex structure;
• development of interstitial fibrosis as the disease progresses;
• Detection of macrophages in the microlith location.

Symptoms of alveolar microlithiasis of the lungs

Alveolar microlithiasis for a long time passes unnoticed. However, with progression, complaints of dyspnoea, fatigue, general weakness, palpitations with exercise, chest pain appear. Cough may appear due to the development of chronic bronchitis.

In the stage of the unfolded clinical picture appears cyanosis of the visible mucous membranes, inspiratory dyspnea, thickening of the terminal phalanges in the form of "drumsticks" and changing the nails in the form of "watch glass". With the development of decompensated pulmonary heart, edema on the legs, pain in the right hypochondrium due to the increase in the liver.

Physical examination of the lungs does not reveal any significant changes. Individual patients may have a boxed shade of percussion sound (due to the development of emphysema), crepitation or small bubbling rales in the lower parts of the lungs can be heard.

1 When auscultation of the heart is determined by the accent of the 2nd tone on the pulmonary artery (with the development of pulmonary hypertension), it is possible to form mitral stenosis with the appearance of the corresponding sound symptomatology (clapping I tone, clicking the opening of the mitral valve, the rhythm of the quail, presystolic and proto diastolic murmur). The development of mitral stenosis is due to the calcification of the left atrioventricular orifice.

Laboratory data

1. The general analysis of a blood - essential characteristic changes are not present. With the development of severe respiratory failure, symptomatic erythrocytosis appears, with the addition of purulent bronchitis, ESR increases, and leukocytosis appears.
2. Analysis of sputum and bronchial lavage fluid - microliths can be detected, but this feature is not given much diagnostic significance, as it can be with chronic obstructive bronchitis and pulmonary tuberculosis.

At the same time, it is believed that the concentric structure of the microliths found is characteristic of alveolar microlithiasis.

3. Biochemical blood test - may be hypercalcemia, a slight increase in the phosphate content, but these changes are unconventional and of great diagnostic value do not.
4. Immunological studies - without significant changes.

Instrumental research

1. X-ray examination of the lungs. A characteristic feature of alveolar microlithiasis in the early stage is the detection of predominantly in the middle and lower regions of both light symmetric multiple small-focal shadows of high intensity. Radiological picture resembles scattered sand - a symptom of a "sandstorm". This symptom is considered pathognomonic for alveolar microlithiasis.

With the progression of diseases against the background of the aforementioned symptomatology, there are pronounced signs of interstitial changes (perivascular, peribronchial, interlobular pneumosclerosis), compacted and calcified bronchial walls are revealed. Together with the increase in interstitial changes, the number of focal rashes increases, the transparency of lung tissue decreases. These changes are most pronounced in the lower and middle divisions; in the upper sections, large airy emphysema bullae are sometimes identified.

In the far-reaching stage of the disease, the fine-focal shadows merge into massive darkening areas, they can occupy 1 / 2-2 / 3 of the pulmonary lobe and also capture the upper sections of the lungs. Conglomerates of focal dimming can be so intense and extensive that it makes it difficult to differentiate the shadows of the heart and mediastinum.

Quite often on radiographs one can see calcification along the contours of the heart, as well as subpleural accumulation of lime.

2. Computer tomography of the lungs - reveals diffuse calcification of lung tissue.
3. Perfusion lung scintigraphy with 99mT-s reveals intensive diffuse accumulation of the isotope, confirming the calcification of the lung tissue.
4. The study of ventilatory function of the lungs is characterized by the development of a restrictive type of respiratory failure (decrease in the ZHEL indices).
5. Investigation of the gas composition of the blood - as the disease progresses and respiratory failure develops, the partial pressure of oxygen in the arterial blood decreases.
6. ECG - with the development of pulmonary hypertension, there are signs of myocardial hypertrophy of the right atrium and right ventricle.
7. The study of lung biopsy samples is used to verify the diagnosis. In biopsy material with the help of light and electron microscopy microliths are detected in the alveoli, and in the epithelial cells of bronchioles an excessive amount of glycogen granules is detected.

The examination program for alveolar microlithiasis of the lungs

1. Common blood tests, urine tests.
2. Biochemical blood test: determination of the total protein content, protein fractions, aminotransferases, calcium, phosphorus, alkaline phosphatase.
3. Analysis of sputum and bronchial flushing water is the detection of microliths with a concentric structure.
4. Radiographic examination of the lungs, if possible, a computed tomography of the lungs.
5. Spirography.
6. ECG.
7. Lung biopsy (transbronchial, with its non-informativity - open).

[1], [2], [3], [4], [5]