Malignant pleural effusion

Introduction to malignant pleural effusion Neoplastic pleural effusion is also known as malignant pleural effusion. In most cases, malignant cells can be found in pleural effusion. If pleural effusion is associated with mediastinal or pleural metastatic nodules, malignant cells can be found in pleural effusion. , can diagnose malignant pleural effusion. basic knowledge The proportion of sickness: 0.0032%, more common in the elderly over 60 years old Susceptible people: no special people Mode of infection: non-infectious complication:

Cause of malignant pleural effusion

(1) Causes of the disease

Neoplastic pleural effusion accounts for 38% to 53% of all pleural effusions. Among them, pleural metastatic tumors and pleural diffuse malignant mesothelioma are the main causes of malignant pleural effusion.

(two) pathogenesis

There are many small holes of 2~12nm between the mesothelial cells of the parietal pleura. The pores are directly connected with the lymphatic network. Under normal circumstances, the adult pleural cavity can produce 100-200ml pleural fluid for 24h, filtered by the parietal pleura, and then The pores of the parietal pleura are reabsorbed, while the visceral pleura has little effect on the formation and reabsorption of pleural fluid. The fluid in the thoracic cavity is continuously produced, and is continuously reabsorbed to maintain dynamic balance. The main driving force of pleural effusion circulation is pleural capillary. Hydrostatic pressure in the intravascular and pleural cavity, colloid osmotic pressure, negative pressure in the pleural cavity and patency of lymphatic drainage. The average negative pressure in the pleural cavity of normal people is -0.49 kPa (-5 cmH2O), and the pleural fluid protein content is very high. Less, about 1.7%, with a colloid osmotic pressure of 0.78 kPa (8 cmH2O), the parietal pleura has a systemic blood supply, the capillary hydrostatic pressure is 1.078 kPa (11 cmH2O), the parietal and visceral pleural capillary endosome The osmotic pressure is 3.33 kPa (34 cmH2O). The normal human pleural cavity contains only a small amount (5-15 ml) of liquid to reduce the mutual friction between the parietal pleural and visceral pleura during respiration. The main driving force is abnormal, both Induced pleural effusion, pleural effusion generation mechanism of tumor complex and diverse, summed up in the following areas:

1. The most common pathogenic factors: the pleural tumor metastasis of the parietal and/or visceral layers, which destroy the capillaries and cause fluid or blood leakage, often causing bloody pleural effusion.

2. Lymphatic drainage barrier: Lymphatic drainage disorder is the main mechanism of tumor pleural effusion. Tumors involving the pleura can block the lymphatic surface of the pleural surface, whether it is from the pleura or metastasis to the pleura. The pleural fluid circulation is destroyed, resulting in pleural effusion; in addition, the lymphatic drainage of the parietal pleura mainly enters the mediastinal lymph nodes, and the malignant tumor cells cause obstruction at any part between the pleural pores and the mediastinal lymph nodes, including the formation of tumor cells in the lymphatic vessels. Embolization, mediastinal lymph node metastasis, can cause reabsorption of fluid in the thoracic cavity, leading to pleural effusion.

3. A large amount of protein in the tumor cells enters the thoracic cavity: the tumor tissue on the pleura grows too fast, the cells are easy to fall off, and the tumor cells entering the pleural cavity are necrotic due to lack of blood supply, and the proteins in the tumor cells enter the thoracic cavity, so that the colloid in the pleural cavity Increased osmotic pressure produces pleural effusion.

4. Increased pleural permeability: malignant tumors invade the visceral and parietal pleura, tumor cells are implanted in the pleural cavity, can cause inflammatory reaction of the pleura, capillary permeability increases, fluid infiltration into the pleural cavity, primary Lung cancer or a metastatic tumor of the lung causes obstructive pneumonia, which produces a pleural effusion similar to pneumonia.

5. Decreased pleural pressure, increased hydrostatic pressure of pleural capillaries: bronchial obstruction caused by lung cancer, distal atelectasis, leading to decreased intrapleural pressure, when the intrapleural pressure is reduced from -1.176 kPa (-12 cmH2O) -4.7kPa (-48cmH2O) will have about 200ml of liquid accumulated in the pleural cavity, malignant tumors of the lung can invade the vena cava or pericardium, causing venous return disorder, increased capillary hydrostatic pressure on the pleural surface, pleural effusion produce.

6. Others: tumor cells invade the angiogenic tumor thrombus, which in turn produces pulmonary embolism, pleural effusion; malignant tumor consumption causes hypoproteinemia, plasma colloid osmotic pressure decreases, leading to pleural effusion; after thoracic or mediastinal radiation treatment, can be produced Exudative effusion of the pleural cavity.

Malignant pleural effusion prevention

There is no effective preventive measure for this disease. Early detection and early diagnosis are the key to the prevention and treatment of this disease.

Complications of malignant pleural effusion Complication

Increased hydrostatic pressure in the pleural capillaries, congestive heart failure, constrictive pericarditis, increased blood volume, obstruction of the superior vena cava or azygous vein, resulting in leakage of the thoracic cavity.

Symptoms of malignant pleural effusion Common symptoms Difficulty breathing, shortness of breath, shortness of breath, dry cough

Most patients are mostly cachectic manifestations in the late stage of the tumor, such as weight loss, weight loss, fatigue, anemia, etc., about one-third of patients with neoplastic pleural effusion have no clinical symptoms, only pleural effusion is found during physical examination, the rest 2/3 patients mainly showed progressive exacerbation of dyspnea, chest pain and dry cough, the degree of dyspnea and the amount of pleural effusion, the rate of pleural fluid formation and the patient's own lung function status, when the amount of fluid is small or The formation speed is slow, the clinical difficulty in breathing is light, only chest tightness, shortness of breath, etc. If the amount of fluid is large, the lungs are under pressure, clinically difficult to breathe, and even sitting breathing, cyanosis, etc.; Large, but rapid formation in the short term, can also be clinically manifested as heavier dyspnea, especially in the case of poor lung function compensation, a large number of patients with pleural effusion Position, this can reduce the respiratory movement of the affected side, which is beneficial to the compensatory breathing of the contralateral lung, relieve dyspnea, tumor invasion of the pleura, pleural inflammation and massive pleural effusion caused by parietal pleural stretch Can cause chest pain, when the parietal pleura is invaded, it is mostly persistent chest pain; when the pleural pleura is invaded, the pain is radiated to the affected side of the scapula; a large amount of pleural fluid is often caused by fullness and dullness caused by the pleural effusion, and the cough is mostly Irritant dry cough caused by pleural effusion stimulation of the bronchial wall.

During the physical examination, it can be found that the respiratory movement on the affected side is weakened, the intercostal space is full, the trachea is displaced to the healthy side, and the effusion area is percussed as a voiced sound, and the breath sound disappears.

Examination of malignant pleural effusion

1. Examination of the nature of the pleural fluid

(1) routine examination: malignant pleural effusion is generally exudate, exudative pleural effusion is characterized by protein content of more than 3g / 100ml or specific gravity of more than 1.016, in some patients with long-term pleural leakage, due to fluid absorption in the chest The rate is greater than the rate of protein absorption, and the protein concentration in the pleural fluid is also increased, which is easily confused with the exudate. Therefore, the levels of protein and lactate dehydrogenase (LDH) in the pleural effusion and serum are examined to distinguish the exudate from Leakage is 99% correct, and pleural effusion has one or more of the following characteristics: exudate:

1 pleural fluid protein / serum protein > 0.5;

2 pleural effusion LDH / serum LDH> 0.6;

3 pleural effusion LDH> 2/3 of the upper limit of serum LDH.

Most of the thoracic exudate is misty due to white blood cells. The cytological examination of exudative pleural effusion is (1 ~ 10) × 109 / L, and the white blood cell count < 1 × 109 / L is the leakage. >1×109/L is empyema, neutrophils are mainly inflammatory diseases in pleural fluid, and progressive tuberculosis, lymphoma and cancer are more common in lymphocytes, and the red blood cell count exceeds 1×1012/ L's whole blood pleural fluid is seen in trauma, pulmonary infarction or cancer.

The level of glucose in the pleural fluid is lower than the blood glucose level found in tuberculosis, rheumatoid arthritis, empyema and cancer. The pH of the pleural fluid is usually parallel to the arterial blood pH, but is usually low in rheumatoid arthritis, tuberculosis and cancerous pleural fluid. At 7.20.

(2) cytological examination: in patients with cancerous pleural effusion, about 60% of the patients can be found in the first time to check the specimens. If the samples are taken three times in a row, the positive rate can reach 90%. The extraction of several specimens in fractional sampling helps to improve the diagnostic rate because the freshly extracted cells are included in the repeatedly extracted specimens, and the early degenerated cells are removed in the previous thoracentesis. The mechanism of pleural effusion caused by cancer In addition to direct invasion of the pleura, including lymphatic or bronchial obstruction, hypoproteinemia, it should be noted that pleural effusion cytology in patients with lymphoma is unreliable.

2. Pleural biopsy

Cancer often involves the local pleura, and the positive rate of pleural biopsy is about 46%. The pleural cytology combined with pleural biopsy can make the positive rate reach 60%-90%.

3. X-ray inspection

When a small amount of pleural effusion occurs, the fluid accumulates in the lowest part of the pleural cavity - the rib angle, and the X-ray image can be flattened as the rib angle. At this time, the pleural effusion is estimated to be about 200 ml, and the middle pleural effusion is After the standing position, the anterior X-ray image shows that the liquid is above the surface of the sputum, showing a typical exudate curve with a low inner side and gradually rising to the outer side. This boundary line is a transitional zone where the X-ray projection density changes. It does not really represent the state of existence of the fluid in the chest. The formation of the exudate curve is due to the fact that the liquid close to the lateral chest wall is exactly tangent to the X-ray, so the height of the liquid surface can be fully displayed, and in the chest cavity where the lung tissue exists. In the middle and inner side, the liquid is present in front of and behind the lungs, and the state in which the lungs are suspended in the pleural fluid is thicker on the mediastinum side, and the outer lung tissue becomes thinner, that is, the thickness of the liquid in the chest is the thinnest on the inner side. The thicker the outer side, the more the lung tissue is set off, even if the plane of the effusion in the thoracic cavity is at the same height, and the chest X-ray shows that the liquid surface gradually becomes lower from the outside to the inside, on the lateral chest image, the middle amount Pleural effusion It is now an arc-shaped exudate curve across the anterior and posterior thoracic cavities. The front and rear are high and the middle is low. When the patient undergoes thoracic puncture and treatment, the gas can overflow into the chest cavity, showing a liquid-vapor level on the chest X-ray, and a large amount of pleural effusion. When the curved liquid level of the exudate curve exceeds the upper edge of the hilar, the X-ray image shows only a small part of the translucent lung tissue on the inner side of the lung tip, and the affected side is completely opaque; The rib space is widened, the rib is flat; the heart is shifted to the healthy side, and the trachea is displaced to the healthy side; when a large amount of pleural effusion is on the left side, the arched dome of the diaphragm is reversed in the expiratory phase, while sucking The vaulted arch of the gas-phase diaphragm moves upwards, forming a contradictory movement of the diaphragm. This phenomenon only occurs on the left side, especially when the stomach bubble is obvious. It can be clearly observed under the fluoroscopy. The liver under the right diaphragm can block the right. Reversal of the lateral diaphragm.

4. Chest CT examination

It can clearly show the presence of fluid in the thoracic cavity and the amount of fluid. In the supine position, the fluid accumulates in the back of the chest, and the lungs can be compressed. The Housefield unit is 1 to 15, depending on the content of the pleural fluid. Differences, at the same time, CT can be helpful for the etiology of pleural effusion, such as intrapulmonary tumors, chest wall tumors, especially after patients undergoing artificial pneumothorax, CT examination can improve the accuracy of tumor invasion and mediastinal diagnosis, in general Pleural calcification often suggests benign lesions, such as tuberculous pleurisy, suppurative pleurisy, and occasional pleural calcification in patients with pleural mesothelioma; Montalvo proposes four CT signs that contribute to the diagnosis of malignant tumor pleural metastasis:

1 annular pleural thickening;

2 nodular pleural thickening;

3 wall pleural thickening > 1cm;

4 mediastinal pleura was attacked.

5. Ultrasound examination

The pleural effusion is in the dark area of the ultrasound examination. It also shows the width, range, depth of the body surface and the internal structure of the pleural effusion, the characteristics of the liquid echo, the extent of the lesion and its relationship with adjacent tissues. In addition, under the guidance of ultrasound, pleural effusion can be performed accurately, and a pleural biopsy of the pleural or subpleural mass can be performed. It is generally considered that the accuracy of ultrasound diagnosis of pleural effusion (92%) is superior to that of the X-ray ( 68%).

6. Thoracoscopy

1 aspiration, collection of pleural effusion, cytological examination;

2 Exploring the pleural cavity and biopsy the suspicious lesions of the pleura, lungs and pericardium, while other examination methods do not show these small nodules well;

3 Histological examination or culture of suspicious mediastinal or hilar lymph node sampling, in addition, thoracoscopy can also be performed in patients with cancerous pleural effusion.

Thoracoscopy can accurately acquire diseased tissue under direct vision, making it highly sensitive to the diagnosis of various pleural malignant diseases, reaching 80% to 100%, and rarely have false negative results in a thoracoscopic, In a comparative study of thoracic cytology and closed pleural biopsy, Loddenkemper reported a diagnostic sensitivity of 95%, 62%, and 44%, respectively. Menzies and Charbonneau reported in a prospective study of 102 unexplained pleural fluids. The accuracy of the diagnosis of pleural malignant disease was 96%, the sensitivity was 91%, and the specificity was 100%.

Thoracoscopy can accurately obtain specimens under direct vision in the diagnosis of pleural mesothelioma, so the diagnostic accuracy is extremely high. Compared with thoracotomy, thoracoscopic can obtain the same high-quality tissue specimen for diagnosis, and at the same time, the thoracic cavity. The mirror can also perform accurate clinical staging of malignant tumors.

VATS or thoracoscopic examination of cancer patients is generally effective and well tolerated, but chest and closed pleural biopsy is relatively less traumatic, can be performed at the bedside, and can be about 2/3 The patient made a definitive diagnosis and clinically used VATS for patients whose chest or closed pleural biopsy could not be clearly diagnosed.

Diagnosis and differentiation of malignant pleural effusion

It is clear that when pleural effusion occurs in the course of patients with metastatic cancer, the diagnosis of effusion is often not very important. It is mainly used to treat primary tumors. Systemic systemic treatment should be taken before septic symptoms occur. Patients with respiratory distress and need local treatment should have a clear diagnosis of pleural effusion before treatment begins.

When patients with malignant tumors have new pleural effusions, they should first look for the underlying cause of leakage, completely eliminate heart failure, tuberculosis and other causes of idiopathic pleural effusion, thoracic puncture and biochemical analysis of pleural effusion and Tumor cell examination, or closed pleural biopsy, can generally confirm malignant pleural effusion.

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