Pediatric idiopathic pulmonary fibrosis

Introduction to idiopathic pulmonary fibrosis in children Children with idiopathic pulmonary fibrosis (IPF), also known as idiopathic fibrotic alveolitis, Hamman-Rich syndrome, idiopathic diffuse pulmonary interstitial fibrosis, European scholars call it cryptogenic fibrosis Alveolitis, now referred to as fibrotic alveolitis (FA). It is an unexplained diffuse pulmonary fibrosis, which may not be a disease, but only the end stage of chronic interstitial pneumonia caused by various causes. Clinically characterized by irritating dry cough, shortness of breath, progressive dyspnea, and hypoxemia, the condition often progresses and eventually dies due to respiratory failure. basic knowledge The proportion of illness: 0.0005% Susceptible people: children Mode of infection: non-infectious Complications: pulmonary fibrosis, pneumothorax, respiratory failure

The cause of idiopathic pulmonary fibrosis in children

(1) Causes of the disease

The cause of the disease is unknown, and it is believed to be related to genetic and immune factors. Some people have considered possible infections with viruses and bacteria, inhalation of dust and gases, and drugs may be predisposing factors. It is now considered to be an immune abnormality and may be an immune complex disease. Some people think that it is a connective tissue disease and an autoimmune disease, but they have not been confirmed. The disease is also related to genetic factors, because some cases have a clear family history, which can occur in twins.

(two) pathogenesis

The pathological features are diffuse alveolitis and pulmonary interstitial fibrosis. The typical histological changes are interstitial diffuse fibrous tissue and collagen tissue hyperplasia and disorder, alveolar structure destruction, fusion into a capsule, the cyst wall composed of fibrous tissue and proliferating type II alveolar epithelial cells. Under electron microscope, type I alveolar cells disappeared, type II cells increased and proliferated, alveolar capillary membrane thickened, immune complexes and complement deposition were observed in alveolar wall and interstitial, bronchiolar smooth muscle hyperplasia, and pulmonary arteriolar wall thickened. The alveolar septum is characterized by lymphocytes, plasma cells, monocytes, histiocytes, and a small number of neutrophils and eosinophils. The alveolar cavity is characterized by cellular and fibrinous exudate.

Prevention of idiopathic pulmonary fibrosis in children

The cause of this disease is unknown, and it is believed to be related to genetic and immune factors. Therefore, there is currently no specific prevention method.

Complications of idiopathic pulmonary fibrosis in children Complications pulmonary fibrosis pneumothorax respiratory failure

Pulmonary fibrosis, pneumothorax, mediastinal and subcutaneous emphysema, often secondary infection, eventually developed into respiratory failure and right heart failure. Most patients die of respiratory failure associated with respiratory infections.

Symptoms of idiopathic pulmonary fibrosis in children Common symptoms Loss of appetite, fatigue, sputum, bloodshot, shortness, dryness, cough, dyspnea, right heart failure, clubbing (toe)

The disease can occur in children and young children, the smallest visible in 4 months of babies. The onset is mostly hidden. The onset of symptoms before 6 months is mostly acute from 6 months to 2 years old, which may be acute or chronic, and most occur after 2 years of age. Clinical symptoms with dry cough are more common diseases, which may be associated with blood stasis, shortness of breath, progressive dyspnea, aggravation after exercise and cyanosis, generally no fever, may have weight loss, fatigue, loss of appetite and pulmonary heart disease. Finally developed into respiratory failure and right heart failure. Most patients die of respiratory failure associated with respiratory infections. Physical examination showed that the child with dysplasia was diagnosed with lung sputum, and the sound of the small sputum was heard at the bottom of the lung. It was called Velcho snoring and had obvious clubbing (toe). Laboratory examination of ECG lung function and pulmonary X-ray can help diagnose.

Examination of idiopathic pulmonary fibrosis in children

1. General examination 30% to 50% of patients may have rheumatoid factor and anti-nuclear antibody positive, some patients with increased erythrocyte sedimentation rate, may have high gamma globulinemia, cold globulin positive. Eosinophilia can be seen.

2. Early blood gas analysis for hypoxemia without hypercapnia, but hypercapnia can occur in the late stage. Hypoxemia is associated with exertion or exercise, ie, hypoxemia is aggravated when exerting force or exercise.

3. Pulmonary function tests showed restrictive ventilatory disorders. All lung volume values decreased significantly in proportion, such as lung capacity, functional residual capacity, and total lung volume; pulmonary compliance and diffusion function were also significantly reduced, with the latter appearing early and the detection rate was high.

4. There are more inflammatory cells in the bronchoalveolar lavage fluid of bronchoalveolar lavage fluid, and there are relatively more mast cells.

5. Lung biopsy can confirm the diagnosis. Open chest or thoracoscopic lung biopsy is considered the "gold standard" for the diagnosis of this disease. To obtain a representative specimen of the lung, at least two different sites of biopsy should be avoided in the apex and middle lobe, mostly in the ipsilateral upper and lower lobe. Open chest or video-assisted thoracoscopic lung biopsy can more accurately distinguish the extent of inflammation and fibrosis. It has certain diagnostic value for determining the degree of activity of alveolar inflammation and end stage pulmonary fibrosis. The histopathological findings were as follows: the naked eye was normal in the early stage, but there were lymphocytes and plasma cells infiltrating around the alveolar wall, alveolar and bronchi, and occasionally eosinophil infiltration; in the late stage, diffuse honeycomb-like changes were observed. Under low magnification, the normal lung tissue, interstitial inflammation, fibrosis and honeycomb-like changes are unevenly distributed, and the peripheral lung parenchyma is the most serious. Interstitial inflammation is a flaky distribution, including alveolar septal lymphocytes and plasma cell infiltration, accompanied by alveolar type II cell proliferation.

1. X-ray examination of lung X-ray changes often coincide with pathological changes, showing a wide range of granules or dot-like shadows or nodules. In the later stage, the dotted shadows in the middle and lower lung fields are diffuse, and as the fibrosis becomes more and more dense, a thick strip-like shadow appears. When the interstitial fibrous tissue contracts, the alveoli and bronchioles expand to form a honeycomb lung. Sometimes pneumothorax, mediastinum and subcutaneous emphysema can be seen, often with secondary infection.

2. The electrocardiogram can show signs of right heart hypertrophy.

3. Lung dysfunction Airway resistance does not increase, but there are restrictive ventilatory disorders with decreased lung capacity, decreased lung capacity, decreased lung compliance, and decreased lung diffusion.

4.CT shows a wide network of dot-like structures, mixed with small sac-like shadows, increased and extended lung texture, visible strip shadows and dot-like shadows parallel to the pleura, and enhanced lung transparency.

5. High Resolution CT (HRCT) shows fine structure changes:

(1) Frosted glass-like high-density shadow, in which the polycystic changes formed by small bronchiectasis are seen, which is an early change of interstitial pulmonary fibrosis.

(2) The subpleural line showed a subpleural arc with a shadow width of 3 mm, which was found in the early stage of pulmonary fibrosis.

(3) The interlobular septal irregular thickening, the interface with the lung and pleura is irregular, and the lobular structure is deformed.

(4) A diffuse or patchy honeycomb-shaped low-density shadow zone, mostly located in the subpleural region (1 cm in diameter).

Diagnosis and differential diagnosis of idiopathic pulmonary fibrosis in children

It needs to be differentiated from many lung diseases that can cause pulmonary interstitial inflammation or fibrosis, and is distinguished from those who appear as reticular or nodular shadows on X-rays. First, it should be distinguished from miliary tuberculosis and invasive pulmonary tuberculosis, followed by DIP and lymphocytic interstitial pneumonia (LIP), pulmonary giant cell inclusion disease, various chronic interstitial pneumonia, eosinophilic pneumonia, and lung Differentiation of hemosiderin, exogenous allergic alveolitis, pulmonary connective tissue disease, and sarcoidosis.

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