Pediatric desquamative pneumonia

　　1. Etiology

　　The etiology is unknown, and it is unclear whether it is a foreign body reaction, an autoimmune phenomenon, or a sequelae of infection. Due to the detection of rheumatoid factors, antinuclear antibodies, and lupus cells, it was once considered to be a connective tissue disease. The presence of immune complexes and the deposition of IgG and complement in the alveoli suggest that this disease is an immunological disease. Some people also believe it is related to pulmonary alveolar proteinosis. There have been reports of associated congenital rubella following respiratory viral infections such as adenovirus and mycoplasma. There have also been reports of its occurrence in children with inflammatory bowel disease treated with Sulfasalazine. Sometimes, there is no obvious cause.

　　2. Pathogenesis

　　The pathological manifestations of this disease mainly include the accumulation of a large number of detached round, oval, or irregularly shaped type II epithelial cells in the alveolar spaces. In hematoxylin and eosin stained sections, the cytoplasm of the cells shows obvious acidophilic staining. Many epithelial cells contain varying sizes of vacuoles in the cytoplasm. The alveolar walls are thickened, with dilated, congested, and edematous capillaries, and infiltration by monocytes, lymphocytes, and eosinophils.

　　The main manifestations are increased respiratory rate, progressive dyspnea, increased heart rate, cyanosis, dry cough, weight loss, weakness, and decreased appetite, leading to complete fibrosis in the alveolar cavity and cystic honeycomb lung. Most patients develop pulmonary hypertension, pulmonary heart disease, and right heart failure due to pulmonary fibrosis. Fever is usually not more than 38°C. Severe cases may develop respiratory failure and heart failure, and may suddenly die after feeding.

　　It can be divided into two types: primary and secondary. The primary type has an acute onset, and the secondary type occurs after other diseases. The symptoms are very similar to diffuse pulmonary fibrosis, often insidious onset, but can also suddenly occur, mainly manifested as increased respiratory rate, progressive dyspnea, increased heart rate, cyanosis, dry cough, weight loss, weakness, and decreased appetite. Fever is usually not more than 38°C. Severe cases may develop respiratory failure and heart failure, and may suddenly die after feeding. On physical examination, clubbing of fingers and toes may be seen occasionally, and lung signs are not obvious. Sometimes fine moist rales can be heard in the lower lungs. X-ray shows ground-glass or reticular, patchy shadows in the lower lungs, and there may be blurred triangular shadows with unclear edges. These shadows spread from the hilum along the heart border to the base and periphery of the lung. Sometimes, bullae, pneumothorax, and pleural effusion may be seen. In the long term, pulmonary heart disease may occur, and peripheral blood eosinophil counts may be increased.

　　Prognosis: The prognosis for infants is poor. About 20% of patients may spontaneously resolve fibrosis, and the prognosis is poor. Most patients died of heart failure within 2 to 3 weeks or several months, with a mortality rate of 16% in adults. The prognosis has improved after treatment with adrenal cortical hormones, especially when used early, which can save lives. There have been reports of a case of severe desquamative interstitial pneumonia treated with prednisone, who showed significant improvement after 3 weeks. Ten years later, no abnormalities were found in the lungs. However, after lung tissue biopsy showed pulmonary fibrosis, the effect of hormone treatment was poor. There is currently no effective preventive measure for this disease, and early detection, early diagnosis, and early treatment are the key to prevention and treatment.

　　1. General laboratory examination shows no special findings

　　1. Routine blood examination:Blood leukocyte counts are generally not more than 15,000/mm3, and eosinophils may increase.

　　2. Blood biochemistry examination:Serum protein levels are generally unchanged, rheumatoid factor, antinuclear factor, or lupus cells may be positive, and immunoglobulin levels are abnormal.

　　3. Blood gas analysis:There is hypoxemia.

　　4. Lung biopsy:Desquamative interstitial pneumonia is a variant type of idiopathic pulmonary fibrosis, with similar symptoms but明显 different changes in lung tissue under the microscope, and can have extensive scarring.

　　2. Auxiliary examination

　　1. Imaging characteristics

　　(1) Chest X-ray: 20% of patients have chest X-rays that are nearly normal, 25% of patients show patchy indistinct shadows or diffuse shadows, and there are diffuse ground-glass changes in the middle and lower lung fields. Later, linear, reticular, and nodular interstitial imaging may also appear.

　　(2) CT: High-resolution CT scans in about 1/4 of patients show diffuse ground-glass changes in the middle and lower lung fields, with linear, reticular, and nodular interstitial images appearing later.}

　　2. Pulmonary function tests:Restrictive ventilatory impairment, accompanied by decreased diffusion function and hypoxemia.

　　Dietary guidelines for children with desquamative pneumonia: especially juice; fresh fruits and vegetables; oily fish, eggs, and other foods rich in vitamin A. Pay attention to the proportion of sugar, fat, and protein in food, and pay attention to the content of vitamins and other essential nutrients for the body. Avoid cold, hot, and hard foods: such as, cold and hot foods and drinks. Avoid spicy foods, such as chili, mustard, pepper, strong tea, coffee, cocoa, and other food or drink.

　　1. Treatment:Oxygen therapy is given to patients with hypoxemia, antibiotics are used to control infection, and drugs are used to correct heart failure. A larger dose of prednisone (prednisone) 3-8mg or prednisolone (prednisolone) 2mg/(kg·d) can be used, first for 8 weeks and then gradually reduced, followed by maintenance dose for 2 years, which can improve clinical and X-ray changes, about 80% effective. If hormones are ineffective, azathioprine, cyclophosphamide, and benzyldiethylhexyl nitrosamine can be tried. In necessary cases, pressure inhalation or high-frequency jet ventilation can be used. At the same time, digoxin should be used quickly to control heart failure. The X-ray shadow disappears later than the improvement of clinical symptoms, and symptoms can recur after stopping hormones. Some people also reported that chloroquine treatment is effective. Recently, there have been reports of lung transplantation treatment abroad, but the effectiveness is still uncertain.

　　2. Prognosis:Poor prognosis in infants with the disease. About 20% of patients can recover spontaneously without treatment, while those with fibrosis have a poor prognosis. In the past, most patients died of heart failure within 2 to 3 weeks or several months. The mortality rate in adults is 16%. After treatment with adrenal cortical hormones, the prognosis improves, and early use can save lives. There are reports of using prednisone to treat one case of severe desquamative interstitial pneumonia, which showed significant improvement after 3 weeks, and there were no abnormalities found in the lungs after 10 years of follow-up. However, the effect of hormone treatment is poor after showing lung fibrosis in lung tissue biopsy.