I. Definition
Tuberculous pleurisy is an inflammation of the pleura caused by the entry of tubercle bacilli and their metabolites into the pleural cavity of a highly allergic organism. It is the most common form of pleurisy.
The etiology of tuberculous pleurisy is Mycobacterium tuberculosis (Mycobacterium tuberculosis), and its occurrence is related to two important factors, namely the stimulation of the pleura by Mycobacterium tuberculosis and its metabolites and the increased susceptibility of the body. When the organism is in a high degree of metaplasia, the invasion of M. tuberculosis and its metabolites into the pleura causes exudative pleurisy, while when the organism is hypersensitive to M. tuberculosis, only a limited dry pleurisy is formed. Few patients progress from dry pleurisy to exudative pleurisy.
Clinical manifestations
Tuberculous pleurisy includes dry pleurisy, exudative pleurisy and tuberculous pustulosis, and its clinical manifestations are different.
(i) Dry pleurisy
The main symptom is chest pain, which is severe pinprick-like pain, and is worse when deep breathing and coughing, mostly occurring in the axillary lower chest. A few patients have mild to moderate fever, dry cough and other symptoms of tuberculosis toxicity. Signs include restricted respiratory movements on the affected side, decreased breath sounds and pleural friction sounds.
(ii) Exudative pleurisy
Clinical symptoms vary widely depending on the site of onset and the amount of fluid accumulation. The onset is often acute, but may be slow.
Tuberculosis symptoms: 80% of patients have fever, mostly moderate fever, often accompanied by malaise, poor performance, night sweats, etc.
Chest pain: It is very much related to the stage of development and location of the disease, and it is common in the early stage of the disease and the late stage of the disease, and it is pinprick-like or vague.
Cough: Most of them are paroxysmal irritating dry cough.
A large amount of fluid may cause shortness of breath and dyspnea.
The signs of fluid accumulation vary with the amount of pleural fluid. When the amount of pleural fluid is large, the affected side of the chest is full, the respiratory motion is weakened, the percussion is turbid, and the breath sounds on auscultation are reduced or absent. A large amount of pleural fluid trachea shifts to the healthy side.
(iii) Tuberculous abscess chest: generally slow onset, mild symptoms, most of them have symptoms of tuberculosis toxicity. Sudden rupture of the subpleural cavity and severe infection of the pleura, with rapid onset and obvious symptoms of systemic toxicity, may present with high fever, severe chest pain and dyspnea. If there is a bronchopleural fistula, there may be a violent irritating cough, often aggravated by secondary bacterial infection. Signs are generally similar to those of exudative pleurisy. In chronic cases, the thorax is collapsed, the rib space is narrowed, the breath sounds are reduced, the mediastinum is shifted to the affected side, and there are often pestle-like fingers (toes).
Laboratory tests and special tests
Chest X-ray: It has important diagnostic value for various types of pleurisy. Its X-ray performance may have the following characteristics.
(1) Dry pleurisy X-rays often have no special positive findings.
(2) A small amount of fluid leakage, and blunting of the angle of the rib diaphragm is seen when the leakage amount reaches 300 ml or more.
(3) In moderate effusion, there is a high external and low internal concave surface with an upward curved density increase shadow.
(4) In a large amount of effusion, there is a large uniform dense shadow, and the mediastinum is shifted to the healthy side.
(5) Interlobular effusion shows a pyknotic shadow, and its location corresponds to the location of the interlobular fissure. The encapsulated effusion is a flat mound-shaped shadow against the chest wall. In the case of fluid at the base of the lung, a transverse photograph is taken on the affected side, and the fluid and the lateral chest wall show a clear band-like shadow.
CT examination A definite diagnosis can be made for small amount of pleural effusion and encapsulated effusion in special areas (including interlobular, fundus and mediastinum). It is of high value for the detection of pleural adhesion thickening and its degree, as well as other pleural lesions.
Laboratory tests
Pleural effusion examination is very important for diagnosis and differential diagnosis.
Routine examination Pleural fluid is exudate, usually straw yellow, clear or slightly cloudy. A few of them can be yellow, dark brown or even bloody, and can form jelly-like clots after placement. The specific gravity is more than 1.018, pH is between 7.0-7.3, mucin test is positive, protein quantification is >30g/L, cell count (0.5-2) × 109/L, early neutrophils are predominant, and later gradually turn to lymphocytes.
Enzymatic tests are valuable for differential diagnosis
① adenosine deaminase (ADA) >45u/L, pleural fluid to serum ADA ratio >1, ADA is significantly higher than that of cancerous pleural fluid.
②Lysozyme (LZM)>80μg/ml, pleural fluid to serum LZM ratio>1, mostly tuberculous.
③Lactate denitrogenase (LDH) >200u/L, higher than leaky fluid and lower than cancerous pleural fluid.
Bacteriological examination of pleural fluid The positive rate of detecting tuberculosis bacilli by pleural fluid smear and collection method is not high. The positive rate of pleural fluid culture is generally 8%-20%, and the positive rate can be significantly increased by using pleural biopsy tissue smear or culture of tuberculosis bacilli.
Pleural fluid TB polymerase chain reaction (PCR) + probe test. PCR is an in vitro amplification technique of DNA of a specific nucleic acid sequence of M. tuberculosis mediated by a pair of specific oligonucleotide primers. It can increase the copy number of a specific nucleic acid sequence millions of times in a short period of time, on the basis of which probe hybridization is performed, improving the sensitivity and specificity of detection. The results of the study show that sputum PCR + probe detection can obtain a significantly higher positive rate than smear microscopy and a slightly higher positive rate than culture, and it is time-saving and rapid, making it an important reference for the diagnosis of tuberculosis etiology.
Ultrasonography Ultrasonography is more sensitive in detecting pleural effusion and can detect a small amount of effusion in the angle of the rib diaphragm. b-mode ultrasonography can observe the chest wall and pleura, indicate whether there is thickening of the pleura, and examine the masses hidden by pleural fluid. It can also be accurately localized, especially for small amounts of fluid or encapsulated fluid, and can suggest the puncture site, depth, and range to guide thoracentesis and fluid extraction. Under its guidance, it can also biopsy pleural and subpleural masses to improve the success rate.
Pleural biopsy is important for the diagnosis and differential diagnosis of tuberculous pleurisy. Pleural needle (modified Cope needle is mostly used in China) biopsy positive rate can reach more than 80%, easy to operate, less invasive, and widely used in clinical practice. Thoracoscopy can directly visualize the site of lesion and biopsy at multiple sites, with a positive rate of up to 93%, and is used for those whose diagnosis cannot be confirmed by conventional examination.
Tuberculin skin test Tuberculous pleurisy is mostly positive, and a strong positive test indicates that the organism is in a hypersensitive state, which is helpful for diagnosis. Positive serum or pleural fluid anti-tuberculosis antibody (TB-Ab). Since the specificity is not strong and the sensitivity is low, further research is needed.
IV. Diagnosis and differential diagnosis
The diagnosis can be made in most cases based on history, signs, X-ray, ultrasonography and pleural fluid examination. Pleural biopsy and bacteriological examination have confirmatory value. In particular, pleural needle biopsy has a high positive rate and is of great significance in the diagnosis of tuberculous pleurisy. The differential diagnosis of exudative pleurisy involves firstly determining the presence of pleural effusion and secondly the nature of pleural effusion, and after determining that it is exudative, the etiology should be further analyzed.
Among exudative pleurisy, tuberculous pleurisy takes the first place, followed by cancerous pleurisy, and exudative pleurisy caused by other diseases only accounts for a minority. The most important clinical differential diagnosis is to distinguish it from carcinomatous pleural fluid, followed by bacterial pleurisy.
Cancer pleurisy is slow in onset, often without fever, with persistent chest pain, and in more than 50% of patients, primary tumors or metastases can be found. Pleural effusion is bloody, often superficial to deep, and growing rapidly; ADA<40u/L,LZM<65μg ldh="">500u/L. CEA pleural fluid/serum ratio>1 is mostly suggestive of cancerous pleural fluid. Positive pleural biopsy and finding of cancer cells in pleural fluid can confirm the diagnosis.
Bacterial pleurisy Acute onset, clinical course of pneumonia, pleural fluid mostly occurs on the same side of pneumonia, pleural fluid WBC>5×109/L, neutrophil predominance, pleural fluid smear or culture with pathogenic bacteria growth, can confirm the diagnosis.
V. Treatment
Patients with tuberculous pleurisy are mostly in a highly sensitive state and often have other underlying or visible tuberculous lesions present, which should be treated actively to achieve rapid control of disease progression, reduce sequelae and decrease the occurrence of intrapulmonary or extrapulmonary tuberculosis in the future. The principles of treatment are reasonable and effective chemotherapy, early thoracentesis and aspiration, and appropriate application of glucocorticoids.
(i) Anti-tuberculosis drug therapy
The principles and regimen of antituberculous chemotherapy for tuberculous pleurisy are the same as those for active pulmonary tuberculosis. The current recommendations are isoniazid (H), rifampin (R), pyrazinamide (Z). The 6-month short course chemotherapy regimen based on ethambutol (E) has the advantages of short course, high efficacy, low adverse drug reactions and easy supervision. The vast majority of patients can achieve satisfactory results with 2S(E)HRZ/4HR; 2S(E)HRZ/4H3R3 regimens, and the course of treatment can be extended appropriately for a small number of pleurisy with poor efficacy or due to hematogenous dissemination.
The common doses are H 0.3g/d, R 0.45-0.6 g/d, E 0.75-1 g/d, rifampicin on an empty stomach, Z 1.5 g/d in divided doses, and streptomycin (S) 0.75 g/d intramuscularly.
(ii) Thoracentesis aspiration
Early thoracentesis and aspiration is an important therapeutic measure for tuberculous pleurisy. It not only helps to diagnose, but also can relieve pulmonary and cardiovascular compression, reopen the lungs, improve breathing and reduce toxic symptoms. More importantly, it prevents fibrin deposition and pleural thickening from impairing lung function. When this disease is diagnosed, the pleural fluid should be actively aspirated along with intensive chemotherapy.
A small amount of effusion usually does not require aspiration, or only diagnostic puncture. Fluid accumulation of moderate amount or above should be aspirated early, in principle 2-3 times a week until complete absorption of pleural fluid. The amount of fluid should not exceed 1000ml each time, too much and too fast fluid extraction will cause a sudden drop in chest pressure, which may lead to pulmonary edema and circulatory disorders. Occasionally, pleural reaction or intrathoracic hemorrhage, pneumothorax, air embolism, etc. may occur as a result of thoracentesis, which should be treated promptly and prevented.
(iii) Glucocorticoid therapy
Glucocorticoid can reduce the metaplasia and inflammation reaction of the body, make the toxic symptoms reduce rapidly, promote the absorption of pleural fluid, and prevent the thickening of pleural adhesions. On the basis of effective anti-tuberculosis chemotherapy, satisfactory results can be obtained with hormones. In acute tuberculosis exudative pleurisy with serious toxicity symptoms and more pleural effusion, glucocorticoids can be added early while chemotherapy and fluid extraction. Usually prednisone 30-40mg/d, divided or taken in a single dose.
When the body temperature is normal, the systemic toxicity symptoms subside, and the pleural fluid is absorbed or significantly reduced, the dosage should be gradually reduced to discontinued, and the general course of treatment is 4-6 weeks, and the rebound phenomenon of pleural fluid should be noted during the process of hormone dosage reduction. Hormone has suppressed the immune function and may cause the spread of tuberculosis lesions, so strong anti-tuberculosis drugs must be given at the same time as applying hormone.
For those whose pleurisy becomes chronic, hormone therapy is not suitable. For simple tuberculous abscess chest, systemic anti-tuberculosis treatment should be strengthened by repeated pleural aspiration, flushing of abscess cavity and local injection of anti-tuberculosis drugs. If bacterial infection occurs, additional antibacterial drugs should be used for systemic and local treatment in a timely manner. If the above treatment cannot be controlled, closed drainage of the chest cavity should be performed to drain the pus.
(iv) Surgical treatment
If the pleural fluid is not absorbed for a long time or becomes abscess, surgery is recommended. If the tuberculous abscess chest is not cured by active medical treatment for a long time or combined with bronchopleural fistula, surgical treatment should be considered. Surgical treatment is the same as that for chronic abscess chest.