OVERVIEW
Pulmonary cystic fibrosis (CPF or CF), is a congenital disease with family autosomal recessive inheritance. It is most common in white North Americans and rare in other ethnic groups. As a lesion of an exocrine gland, the gastrointestinal and respiratory tracts are often involved. It is diagnosed on the basis of increased levels of NaCl in sweat, reflecting abnormal function of the exocrine gland. Due to the increased mucus in the bronchial tubes, the bronchial tubes can be obstructed, making it easy for certain bacteria (such as Staphylococcus aureus and Pseudomonas aeruginosa) to grow and multiply, which further causes recurrent infections of the lungs and bronchial tubes, followed by cystic fibrosis, which can severely impair lung function, and further lead to hypertrophy of the right heart and heart failure with the aggravation of the lung disease and the impairment of lung function. Due to the lack of pancreatic enzymes, it can also cause clinical manifestations such as dyspepsia and developmental disorders.
Etiology
It has been suggested that the development of CF is associated with mutations in the transmembrane regulatory factor gene (CFTR) that lead directly to Pseudomonas aeruginosa infection. The immediate consequence of Pseudomonas aeruginosa infection is the development of airway mucus obstruction and progressive lung tissue necrosis.
Symptoms.
The typical clinical presentation is that the child has recurrent respiratory and pulmonary infections and shows signs of pancreatic exocrine gland insufficiency, such as profuse fatty stools. The first respiratory symptom is a cough, mainly dry, with thick, sticky sputum that is not easily coughed up, followed by paroxysmal coughing and increased sputum volume. There can be chest tightness, breathlessness and dyspnea and other hypoxic manifestations, these symptoms can last for weeks or even months. These symptoms may last for weeks or even months. If there is repeated hemoptysis when combined with bronchiectasis, there may be cyanosis and pestle fingers in the later stage, and often combined with serious complications such as pneumogenic heart disease and heart failure.
Examination
1. Sweat test
Positive.
2. Pancreatic stimulation test
Measurement of pancreatic enzymes, pancreatic enzymes are significantly decreased or close to normal, but bicarbonate is significantly decreased.
3.X-ray examination
(1) Lung texture changes in the early stage of the lesion, bronchiectasis manifested as enhanced lung texture.
(2) Lobular pneumonia-like changes are manifested as obstruction and infection of the bronchial tubes below the segments, forming small patchy fuzzy shadows.
(3) Lung field changes with ring-like shadows around the pulmonary hilum are important X-ray signs of cystic cavities at the beginning of the bronchus. These ring-like shadows are abnormal bronchial dilatation rather than true cavities, which are more pronounced in the upper lobes, and there can also be air accumulation signs in the lower lobes, including loss of peripheral vascular distribution and diaphragmatic hypoplasia. Limited obstructive atelectasis, emphysema, lung abscess and pneumogenic heart disease may also be present.
(4) Bronchography shows mild to moderate columnar bronchiectasis, which often occurs in the upper lobes of both lungs.
4. Chest CT examination
(1) Bronchial wall thickening and bronchiectasis can be widely distributed in all lobes of the lungs, especially in the upper lobes of the lungs. Bronchial dilatation is mainly mild or moderate columnar bronchial dilatation. Bronchial wall thickening can occur in both dilated and non-dilated bronchioles, often with mild thickening, and the walls are relatively smooth inside and outside.
(2) Diffuse emphysema in both lungs is characterized by low and uneven density of the lung fields, and the degree of the lesion varies from case to case, and it is more common in infants or children.
(3) Bronchial mucus plugs are formed when mucus secretions are retained in the airways. Depending on the direction of the bronchial tubes in which the mucus is retained, they may appear as round, oval, tubular, or “V”-shaped or “Y”-shaped high-density shadows with the tips pointing to the hilum, with uniform density and smooth, sharp edges. The density is uniform, the edge is smooth and sharp, the CT value is generally 15±10HU, but the CT value of the mucus plugs that have existed for a long time can be as high as 40～80HU, and there is no enhancement in the enhanced scan.
(4) Thin-walled air-containing cystic cavity due to bronchial dilatation, emphysematous alveoli and interstitial air cysts form cystic cavities of different sizes, which are mainly distributed in the upper part of both lungs.
(5) Patchy shadows are manifested as infectious bronchopneumonia and subsegmental atelectasis, showing patchy high-density shadows of varying sizes from 1 to 3 cm, which are common in the upper lung fields or more foci are distributed in the upper lung fields.
5. Chest MRI examination
MRI shows that cystic fibrosis in the respiratory system is caused by secretions blocking the bronchial tubes and secondary infections, MRI can better show the bronchial mucus plugs and infectious lesions in the lungs, the mucus plugs are slightly short and long T1 abnormal signals, uniform signals, smooth and sharp edges, with different morphologies and the tips pointing to the lung doors, and the secondary infections are mainly lobular pneumonitis-like lesions.
Diagnosis
Laboratory tests quantify the sweat test for hairy fruity cloudy basil electroosmotic therapy. It is diagnostic because of the presence of high concentrations of NaCl in the sweat, which is usually positive with Cl–>70 mmol/L. Combined with the fact that the child has abnormal functioning of exocrine glands such as pancreatic ducts, the amount of stools is large and more fatty, the child is often prone to respiratory tract infections, the mucus secretion of the respiratory tract increases, which can easily lead to airway obstruction, and combined with the family history, X-rays, CT, and MRI, it can be diagnosed this disease.
Differential diagnosis
Cystic fibrosis often presents with cystic bronchiectasis, so it needs to be differentiated from some diseases that cause cystic bronchiectasis. Cystic bronchiectasis is a complication of recurrent or chronic infections, and its manifestation can be similar to polypoidal cavities, but it is not a true cavity, but a manifestation of polypoidal bronchiectasis with cystic cavities.
1. Gammaglobulin deficiency
This patient is prone to recurrent bacterial infections, secondary airway obstruction and cystic bronchiectasis, and sometimes it is not easy to distinguish from pulmonary cystic fibrosis, but this patient’s blood gammaglobulin is obviously reduced or deficient, and there is no high concentration of NaCl present in the sweat, so it can be distinguished.
2. Recurrent bacterial pneumonia
Recurrent episodes can result in bronchiectasis, and early on this bronchiectasis can be cylindrical and reversible, but after multiple episodes of pneumonia, it can develop into varicose or cystic bronchiectasis due to bronchial damage, which is characterized by being located in the lower lobes. The diagnosis can be obtained with high-resolution CT (HRCT) instead of bronchography.
3. Allergic bronchopulmonary aspergillosis
Asthma can be accompanied by bronchial cystic dilatation, but usually the disease has a late onset, no family genetic history, fiberoptic bronchoscopy can find Aspergillus filaments, and glucocorticoids can be cured.
4. Tuberculous bronchiectasis
Tuberculosis is another cause of cystic bronchiectasis, after long-term tuberculosis infection, cavities can occur in the lung apices and the whole lung, these transparent areas in addition to necrotic cavities must be considered to have bronchiectasis, especially cystic bronchiectasis, but tuberculosis-induced bronchiectasis generally have toxic symptoms, such as low-grade fever, night sweats, etc., and mycobacterium tuberculosis can be found in the sputum.
Complications
If there is recurrent hemoptysis in combination with bronchiectasis, there can be cyanosis and pestle finger in the later stage, often combined with serious complications such as pulmonary heart disease and heart failure.
Treatment
The prognosis of cystic fibrosis is optimistic if a detailed history is taken, early diagnosis is made and reasonable comprehensive treatment is given, with most patients surviving into their 20s or even longer. Otherwise, many children die before the age of 10 years due to recurrent respiratory infections, which eventually lead to severe lung function damage, right heart overload, pulmonary heart disease, cardiac insufficiency and premature death. Therapeutically, since the children have recurrent respiratory infections, antibiotic therapy must be applied to control the inflammation of the respiratory tract and lungs and prevent further disease progression. Other treatments include pancreatic enzyme supplementation, physical therapy, high-calorie diet, and multivitamin supplementation, especially vitamins C and E.
Prognosis
With early diagnosis and rational comprehensive treatment, most patients may live into their 20s or longer.