What Is Alveolar Proteinosis?

The etiology is unknown, it is speculated that it is related to several factors: such as a large amount of dust inhalation (aluminum, silicon dioxide, etc.), decreased immune function of the body (especially infants and young children), genetic factors, alcoholism, and microbial infection. For infections, it is sometimes difficult to confirm whether it is the primary cause or secondary to alveolar proteinosis. For example, cytomegalovirus, pneumocystis carinii, and histoplasma infections have been found to have high protein deposition in the alveoli.

Alveolar proteinosis

The etiology is unknown, it is presumed to be related to several factors: such as a large amount of dust inhalation (aluminum, silicon dioxide, etc.), decreased immune function of the body (especially infants and young children), genetic

Most of the lungs were solidified, yellow or yellow-gray nodules were visible under the pleura, and yellow fluid exuded on the cut surface. Microscopic examination showed that the alveolar and bronchioles were filled with strongly eosinophilic PAS-positive substances. It is a combination of the surfactant phospholipids produced by type alveolar cells and other proteins and immunoglobulins in the alveolar fluid. The alveolar septum and surrounding structures are basically intact. Electron microscopy showed a large increase in alveolar macrophages, swallowing pulmonary surfactant, swollen cytoplasm, and showed a vacuole or foam-like appearance.

There are many hidden attacks, the typical symptoms of which are shortness of breath after activity, and also feel shortness of breath when progressing to rest, cough white or yellow sputum, fatigue, weight loss. When secondary infections occur, fever and purulent sputum are present. A few cases can be asymptomatic, with only abnormal X-ray manifestations. Respiratory dysfunction worsens as the disease progresses, and dyspnea with cyanosis also becomes more severe.

The chest X-rays are diffuse, fuzzy, and nodular shadows that diffuse outward from the hilum on both sides, often fused into flakes, with compensatory emphysema or small translucent areas formed between the lesions.

It is mainly aimed at how to remove protein-like substances deposited in the alveoli. In recent years, double-lumen tracheal catheters (Carlen catheters) or fiberoptic bronchoscopy have been used for saline lavage on one side of the lung or lung lobe, which is performed alternately regularly. The recent curative effect showed that the patients 'dyspnea and lung function were improved, and half of the patients' X-ray films became clear. The long-term effect is mostly in remission, and a small number of patients relapse, often within 6-24 months, and can be reperfused for lung lavage.

Pulmonary alveolar proteinosis (PAP) is a rare respiratory disease characterized by a large number of surfactant proteins and lipids deposited in the alveoli and terminal respiratory bronchioles. According to the onset, it can be divided into two types: primary PAP and secondary PAP. The principle of treatment of secondary PAP is to treat the primary disease.

Alveolar proteinosis is non-specific and should be distinguished from the following diseases: idiopathic pulmonary interstitial fibrosis; alveolar cancer; miliary pulmonary tuberculosis; parenchymal diseases such as viral pneumonia, mycoplasma pneumonia, and chlamydia pneumonia.

May be complicated by lung infection and respiratory failure

1.Avoid infections such as mycobacteria, cardiopulmonary cyst pneumonia, cytomegalovirus, etc .;

2. Pay attention to exercise and improve immunity.

Multi-layer CT manifestations of alveolar proteinosis and imaging pathological comparison studies. Alveolar proteinosis'pap is a rare lung disease with unknown etiology. White mucoid sputum is predominant, non-characteristic, and easily misdiagnosed [1]. The diagnosis mainly depends on pathological examination. The advent of multi-layered ct (msct) makes it possible to complete a high-quality thin-layer lung scan in a single breath-holding time, greatly improving the temporal and spatial resolution of the image, and the high-resolution ct (hrct) of the chest can be clear. Showing the fine structure of the lungs in the secondary lung lobules as a unit greatly improves the value of CT in the diagnosis of lung diseases. This article collects 6 cases of pap confirmed by pathology, and synthesizes the relevant domestic and foreign literature to explore the imaging pathological relationship of pap and its multi-layered ct performance characteristics, in order to improve the understanding and diagnosis of the disease.

Data and methods of alveolar proteinosis

1.1 General Information

Six patients with pap confirmed by pathology from January 2000 to June 2005 were collected as study objects. There were 4 males and 2 females, aged 25 to 55 years, with an average of 42 years. The course of disease ranged from 7 months to 10.3 years, of which 1 case had a history of dust exposure for 5 years. Clinical symptoms include: shortness of breath (6 cases), cough and sputum (5 cases), chest pain (2 cases), bloodshot sputum (1 case), and fever (1 case). Physical examination: 2 cases had no obvious positive signs; 4 cases had double lower lung wet rales; 1 had clubbing fingers; 1 had cyanosis.

1.2 Imaging examination

A ge lightspeed qx / i multi-layer CT scanner was used for conventional chest CT plain scans and enhanced scans, ranging from the apex of the lungs to the base of the lungs. Scanning parameters: layer thickness 5mm, pitch 6: 1, bed speed 15mm / s, tube current 210ma, tube voltage 120kv. The contrast agent used in the enhanced scan was iopanol (300mgi / ml), which was administered via a high-pressure syringe at a dose of 80ml and an injection flow rate of 2.5ml / s. The enhanced scan was performed 32s after the start of administration. Four of them underwent hrct scan of the lesion at the same time. Scanning parameters: tube current 250ma, tube voltage 120kv, layer thickness 1.25mm, interval 1mm, bone algorithm reconstruction.

1.3 Histopathological examination

Six patients received bronchoalveolar lavage (bal) and transbronchial lung biopsy (tblb) after multi-layer CT examination. Two of them were diagnosed with percutaneous lung biopsy because of tblb. Bal fluid (balf) pellets and biopsy lung tissues were stained with he stain, periodic acid (pas), and aussie blue (ab), and observed under an optical microscope.

1.4 Imaging evaluation

The single-blind method was used to analyze the multi-slice CT scan and enhanced performance of 6 patients with 1 professor and 2 attending physicians. Based on the biopsy results, the pathological relationship of pap and its multi-slice CT were analyzed. Performance characteristics.

Alveolar proteinosis results

2.1 Multi-layer CT performance

A total of 6 patients with pathologically confirmed pap in this group were diagnosed with multi-layer CT: 2 cases of idiopathic pulmonary interstitial fibrosis; 1 case of invasive pulmonary tuberculosis; 1 case of alveolar cancer; 1 case of pneumonia; alveolar protein There was 1 case of sedimentary disease with a diagnostic accuracy of 17%. Ground-glass-like high-density shadows scattered in both lungs were seen in all 6 patients. The density was uneven, and the shapes were triangular, square, and polygonal. A few were round, curved, or linear, and all lesions had clear boundaries. In 4 cases, some of the lesions were fused into pieces. In all patients, the lesions were mainly distributed in the hilar area and the field of the lung. The upper and lower lung lobes were visible in the surrounding normal lung tissue. The hrct images of 4 patients also showed increased, thickened, and disordered pulmonary lobular intervals in patchy ground glass shadows, showing a paving stone-like appearance (4'5), as shown in Figure 2. The boundary between the lesion and surrounding lung tissue was clear, and no obvious abnormal manifestations were seen in adjacent lung tissue. No bronchial air image was seen in all patients in this group, and no enhanced lesions and no signs of mediastinal or hilar lymphadenopathy were seen in the enhanced MSCT scan. Heart size and morphology are in the normal range.

2.2 Pathological manifestations

Pathology found that the alveolar cavity of these 6 patients was filled with a large amount of pink cloud-like, amorphous protein-like substances. In 4 patients, lobular septal edema and thickening were seen, and lymphocyte infiltration was seen. There was no significant fibrous tissue hyperplasia and no damage to the alveolar structure in all patients. In all cases, milky white milk-like turbidity was seen in lung lavage, and sediment was seen in 3 cases. Periodic acid pas stain was positive in all cases, and ausin blue (ab) stain was negative.

Alveolar proteinosis

Alveolar proteinosis is very rare in the clinic and was first reported by Rosen et al. [6] in 1958. The etiology and pathogenesis are still unclear. It is currently believed to be related to abnormal metabolism of alveolar surface substances or abnormal clearance of alveolar macrophages. Some patients It may also be related to the specific reaction caused by the inhalation of dust or certain chemicals, or it may be related to the autoimmune mechanism disorder, malignant tumors of the blood and lymphatic system, and the application of cytotoxic drugs. 3.1 Imaging and pathology A large number of pink cloud flocculent or fine granular amorphous protein-like substances are the main pathological changes of pap, but the alveolar wall, bronchial wall and pleural lesions are not obvious. The boundary between the lesion and adjacent normal lung tissue is clear, the alveolar structure remains intact, the alveolar interval is mostly normal, and a few can be thickened by septal edema and lymphocyte infiltration [8]. At different stages of disease development, alveolar proteinosis has different imaging signs. When the lesion only affects the alveolar cavity, the protein-like substance fills the alveolar cavity, and the alveolar septum is free of edema and inflammatory cells exudate. The CT examination shows ground-glass fringy high-density shadows in the lung field, and the lesion forms with surrounding normal lung tissue. Clear demarcation, showing a map-like appearance in the lung field [2'3]. All patients in this group can see this sign. The formation mechanism is not clear, which may be related to the distribution of the lesions in the lung lobules, and the lobular interval has limited the spread of the lesions to a certain extent. According to the literature, even in patients who have undergone lung lavage, the remaining lung consolidation is still well-defined [5]. The MSCT enhanced scan showed no enhancement, indicating a lack of blood supply and no granulation tissue formation. When the lesion involves the lobular interval, which is thickened by edema and infiltration of inflammatory cells, a thickened lobular interval appears in the consolidation area on the hrct, forming a paving stone-like performance around the consolidated lung lobes, which has certain characteristics 4'5]. Four patients in this group saw this sign. hrct can clearly show the secondary lung lobular structure in patients with pap, and find the lung lobular and lobular septal lesions in patients with pap that can not be found by conventional chest radiographs and conventional CT, so it can better assess the scope and severity of the lesions, which is of great value. . The hrct images in this group show that the thickened lung texture of pap patients conforms to the lobular interval travel, which is different from pulmonary fibrosis. Pathologically, there is no fibrotic change in the lobular interval of pap patients. The distribution of pap lesions is more common in both lungs and can only affect one side [9]. It can occur in the center and periphery of the lung field, and there is no significant difference in the distribution of the upper and lower lungs [3'9'10]. It has been reported in the literature that when consolidation alveoli and air-containing alveoli are mixed together, honeycomb-shaped light-transmitting areas can also be seen in consolidation shadows, but bronchial air images are rare [9]. None of these cases were seen. Alveolar proteinosis is a non-infectious lesion. Some scholars believe that the disease is not accompanied by mediastinal or hilar lymphadenopathy. If there is significant lymphadenopathy, it is mostly related to infection [11]. No mediastinal or hilar lymphadenopathy was seen in all cases in this group.

In short, for diffuse lesions of the lung, pap diagnosis is highly suggested when ct appears as map-like and paving stone-like. Chest CT scan, especially hrct, can improve the early correct diagnosis of pap. [4'7'8]. The disease is more common in adults aged 30 to 50 years, occasionally in children and elderly patients, more men than women. Most patients have insidious onset and have no clinical manifestations. Common symptoms include shortness of breath, cough, and a small amount of white mucus sputum after the activity, or dry cough without sputum. People with low fever, fatigue, chest pain, and hemoptysis are rare. In some cases, small pieces of jelly-like substance can be found. In some patients, a slight wet murmur at the bottom of the lungs can be heard on physical examination. About 1 in 5 patients have clubbing fingers, and severe cases can cause cyanosis. The prognosis of patients varies widely, some of which can be resolved on their own, recurrence is common, and about one-third of patients die due to respiratory failure or co-infection.