Pulmonary echinococcosis

Introduction to pulmonary hydatidosis The hydatid cyst disease is a systemic parasitic disease, which is a cystic disease caused by parasitic larvae of the echinococcosis (canine aphid) in the lungs. It is mainly prevalent in areas where animal husbandry is developed. basic knowledge The proportion of illness: 0.0001% (more in the epidemic area) Susceptible population: fecal-mouth transmission Mode of infection: contagious Complications: lung abscess

Causes of pulmonary hydatid disease

(1) Causes of the disease

There are four main species of Echinococcus granulosus: Echinococcus granulosus, Echinococcus multilocularis, Aphis gossypii and A. serrata, among which Echinococcus granulosus and Echinococcus multilocularis are the most harmful to humans. The terminal host of Echinococcus granulosus is a dog or a wolf. The intermediate host is mainly sheep. It also includes hoofed animals such as cattle, horses, pigs, yaks or camels. The terminal host of Echinococcus multilocularis is fox, cat, dog and others. Carnivores, the intermediate host is a rodent-based rodent whose eggs are discharged along with the host's feces, contaminating water sources, pastures and food. After the eggs are swallowed, they are hatched in the duodenum of the intermediate host. The six hooks penetrate into the intestinal wall and pass through the mesenteric venule vessels, invading the capillaries of various organs and tissues. The main parts of the colony are liver and lung, followed by the brain, mediastinum, chest wall, diaphragm, etc., and can be transferred to each other. Organs of the six hooks are often attacked by monocytes, many of which can be eliminated, and the survival continues to develop. The larval stage of the echinococcosis is called the hydatid (commonly known as the worm), usually a single-room type, with a capsule. Bubble state parasitic on the host The larval stage of the echinococcosis is called the multi-room echinococcosis, also known as the globule sputum, which is parasitic in the host tissue for many vesicular erosive structures. The vesicle contains the original taro joint and the gelatinous substance. The internal organs of the host animal are swallowed by animals such as dogs or wolves, and the original head lice can develop into adults in the small intestine to complete their life cycle.

The adult lifespan of Echinococcus granulosus, Echinococcus multilocularis is not long, but Echinococcus and Bulbs can survive for a long time in the host, 20 to 30 years are not uncommon, often with cysts or vesicles and ascus, Sun The morphology of the sac survives in tissues such as the lungs, liver, and brain.

People are infected by close contact with dogs or sheep, or eating unclean, and accidentally swallowing eggs. According to the investigation, there are often piles of eggs in the feces discharged from the final host (dogs), suggesting that the eggs are flying and may inhale through the respiratory tract. It causes infection, regardless of whether it is susceptible to men, women and children. The disease is a natural epidemic disease, widely distributed throughout the world, mainly in animal husbandry areas.

(two) pathogenesis

Six hooks develop into the lungs, surrounded by a large number of macrophages, and eosinophil infiltration, most of the six hooks are killed, only a few survive, about 3 weeks later developed into cysts, about the diameter 2mm, there may be granuloma changes around it, to the 5th month, the diameter can reach 1cm, at this time the production of the sac and the original sputum, most larvae die in about 5 years, but a few continue to grow, forming a huge cyst, volume From hundreds of milliliters to several thousand milliliters, cysts and surrounding tissues form cysts. The capsule wall is divided into inner and outer layers. The outer capsule is the fibrous envelope formed by the reaction of human tissue. The inner capsule is the insect body itself. Two layers: the outer layer is the horn layer, the texture is fragile, and it is easy to rupture; the inner layer is the germ layer, also known as the germinal layer, which can produce the sac, the original scorpion and the ascus, the sac, the original scorpion and the ascus can fall off, float or Precipitation in the sac fluid is called the sac, and the ascus can produce the sun sac. In the larger, older vesicles, there may be hundreds of ascuss. The ascus may collide with each other or the wall vibration may produce echinoecary vesicle tremor. The original head can be formed into other tissues in the middle of the host, such as secondary Cysts, if swallowed by the terminal host, can develop into adult, secretory layer secretory fluid, clear water-like liquid, slightly alkaline, pH 7.6 ~ 7.8, containing chloride, lecithin, protein, glucose, sodium, Potassium, calcium, phosphorus, non-protein nitrogen, urea, amylase and alkaline phosphatase, etc., the vesicle contains toxic albumin, which may be one of the causes of cyst rupture and different degrees of allergic reaction when the cyst fluid leaks. It contains more than a dozen antigens, mainly composed of arc-5 antigen and antigen B. In addition, the germinal layer and the original mites are also antigenic. After the vesicles are degraded or automatically died due to injury, the cyst fluid is gradually absorbed, and its contents are absorbed. It turns into a turbid jelly sample, and finally denatures, cheese, and fibrosis to form a tuberculoma-like mass. The mother sac and ascus can have calcification, and the outer wall calcification is rare. The disease is often chronic, with no obvious symptoms for many years. , in the subclinical worm state, but when the cyst containing the original head lice section with secondary infection, or due to trauma rupture, can promote the spread of hydatid or sputum in the chest, causing acute lung abscess, pus Chest, pus, or chest Pneumothorax; if broken into the pericardium, sudden pericardial tamponade, heart failure, threatening the patient's life; sometimes cyst rupture, a large amount of cyst fluid, debris into the trachea, can cause suffocation death, if you can pass the acute danger period, cyst fluid If the contents such as fragments and clots are coughed up by the trachea, it is possible to obtain healing. The clinical situation caused by the bulb sputum is complicated and the prognosis may be poor.

Pulmonary hydatidosis prevention

Don't let the dog eat the raw animal's internal organs, whether in the slaughterhouse or in the cottage, slaughter the internal organs and dead animals of the livestock to prevent being eaten by the dog, reduce the number of dogs and treat the dog with collective deworming to reduce the echinococcosis In terms of dissemination and personal protection, care should be taken to avoid close contact with carnivores such as dogs that may be infected.

Pulmonary hydatid complications Complications lung abscess

Cyst rupture: 1/3 to 1/2 of patients with pulmonary hydatidosis have cyst rupture, and there are many external shocks, strenuous exercise, severe cough, falls or breath holding, etc., and sudden rupture of larger cysts can cause an emergency. Such as a large amount of pus and capsule suddenly into the trachea, bronchial, can cause severe breathing difficulties, and even suffocation death; broken into the pericardium, large blood vessels, often cause sudden death.

Cyst infection: can cause symptoms similar to lung abscess, such as high fever, chest pain, cough, purulent sputum, increased white blood cells, accelerated erythrocyte sedimentation rate, secondary infection of the respiratory tract and severe cough, often the cause of cyst rupture, severe infection of the body Can die.

Cyst spreading: After the cyst is ruptured, its ascus, sac sand, etc. enter the nearby tissue or blood flow, and can form secondary hydatid cysts in other tissues and organs, causing corresponding clinical manifestations, of which blood-borne dissemination After a period of time, it develops into multiple cysts in the lungs. It is similar to metastases on the X-ray. It is transmitted through the bronchopulmonary and forms a secondary cyst 1 to 3 years later. It is characterized by a large number of cysts and dense Most of them are distributed in the lobe or lung segment. The following leaves are more. The direct spread type is inserted into the adjacent lung by the in situ cyst, and a new cyst is formed in the pleural cavity.

Pulmonary hydatid symptoms common symptoms abscess high fever wheezing hemoptysis shortness shortness cyst

Pulmonary hydatidosis accounts for 12% to 16% of human hydatidosis, male and female incidence is about 2:1, children account for 25% to 30%, most of them are under 40 years old, the youngest is 1 to 2 years old, the largest 60 to 70 years old.

Pulmonary hydatid cysts are slow to grow, such as no complications, can be asymptomatic for many years, from infection to symptoms usually interval of 3 to 4 years, or even a year or two, the symptoms due to cyst size, number, location and complications Different, early cysts are small, generally no obvious symptoms, often after physical examination or when chest disease is found due to other diseases, when the cyst enlarges to cause compression or inflammation, there are cough, cough, chest pain, hemoptysis, shortness of breath and other symptoms, huge cysts Or located near the hilar, may have difficulty breathing, such as esophageal compression, dysphagia, occasional apical cyst compression of the brachial plexus and cervical sympathetic ganglia, causing Pancoast syndrome (shoulder shoulder, arm pain) and Horner Signs (the side of the eye is drooping, the skin is flushed and not sweating). If the cyst breaks into the bronchus, the patient will cough first, then cough up a lot of transparent mucus, and the inner capsule can also be separated, such as being coughed up, The scalp can be found in the fluid, and the secondary bronchial dilatation of the secondary infection is similar to the lung abscess, high fever, cough, sputum and blood, large amount of cystic fluid, dyspnea and suffocation. And the head section spillover, can form a number of new cysts, patients often accompanied by allergic reactions, such as skin flushing, urticaria and wheezing, severe shock, cyst rupture infection, fever, cough and phlegm and other lung inflammation and lung Abscess symptoms, a small number of cysts break into the chest, then form a liquid pneumothorax, and then become empyema or bronchial pleural sputum, fever, chest pain, shortness of breath, bronchospasm and shock eosinophilia and other allergic reactions.

Examination of pulmonary hydatidosis

1. Eosinophilia is not specific.

2. The eosinophil allergy test has clinical significance. The method is to subcutaneously inject 0.3ml of hydatid cyst fluid for 30min and then draw blood. If the eosinophil blood cell count is transiently reduced (below 0.1 or more before injection of the hydatid cyst) Positive.

3. Indirect hemagglutination test (IHA) has high specificity and a positive rate of up to 80%. It is mostly used for the screening and screening of specimens.

4. The intradermal test of the hydatid cyst fluid (cosoni test) has a positive rate of 90% to 95%.

5. The complementation test has a positive rate of 70% to 90%. The diagnostic value of this method is small, but it is helpful for judging the curative effect. For example, the complement fixation test is still positive after 1 year of surgery, indicating that there are still hydatid in the body. The cyst remains.

6. Convective immunoelectrophoresis (EIED) is used to screen all specimens for screening.

7. Latex agglutination test (LA).

8. Enzyme-linked immunosorbent assay (EICB).

9. Spot enzyme-linked immunosorbent assay (BOT-EICB) is a diagnostic test.

Immunodiagnostic tests are very useful for the diagnosis of echinococcosis. Combined with multiple examination results, it is currently the most valuable serological diagnosis. It can be used before invasive examination. The above immunoassay is mainly used for detecting antibodies, and the positive rate is 80%-90. %, false positive 5% ~ 10%, the factors affecting the immune response are mainly antigen specific and sensitive is not ideal, false positive reaction can be seen in patients infected with other intestinal parasitic diseases, cancer and chronic immune diseases, negative results can not be excluded Echinococcus echinococcosis, because some carriers are unable to detect antibodies, and the immune response is monitored in relation to the location, integrity and activity of the larval cysts, with particular attention to the following:

1 The intrahepatic cyst is more likely to activate the antibody response than the intrapulmonary cyst. If the site is neglected, the antibody test is the least sensitive to the complete cystic echinococcosis cyst;

2 The diagnostic rate of cysts in the lung, brain and spleen is lower, while the intracapsular capsule is more irritating to the antibody response;

3 cystic sputum or rupture can stimulate a sudden antibody response;

4 cystic, calcified or dead cysts, serological tests are often negative.

10. X-ray examination of chest X-ray examination is the main diagnostic method for hydatid disease. In the epidemic area, there is a clear history of contact. Most of the X-ray films can be diagnosed. The early diameter of the cyst is less than 1cm, only the edge is blurred. Inflammatory shadows, with a clear outline of >2cm, a rounded shadow with sharp edges, a uniform density and a slight lightness, lower than the density of the heart and substantial tumors, to a clear diagnosis of 6 to 10 cm, the density is close to the parenchyma It is usually single and multiple (Figure 1).

As a liquid cyst, the diaphragm is lowered when the position is inhaled, the head and foot diameter are slightly increased, and when the expiratory diaphragm is ascending, the transverse diameter is slightly longer, the upper and lower sides are slightly shorter ("hydatid breathing sign"), and the larger cyst is the lung. The texture is stretched, and the surrounding lung texture is wrapped around the cyst to the hilar side ("bulb sign"). The large cyst can be lobulated or multi-ringed, and the cyst in the lower lung field "sit" On the diaphragm, the diaphragm position is lowered, or even depressed. Sometimes artificial pneumoperitoneum is required to determine whether it is a thoracic cyst. The large cyst of the upper lung often pushes the mediastinum to the contralateral side, and the mediastinum in the lower lobe is less affected, while the right liver top is affected. The huge cysts clearly shift the heart to the left. This feature is helpful in differential diagnosis. A few cases have atelectasis and pleurisy.

If the small bronchi of the cyst is invaded and a small amount of gas enters between the inner and outer sacs, some special X-ray signs appear (Figure 2):

1 A small amount of gas enters between the inner and outer sacs, and the standing X-ray film gas rises to the upper part of the cyst, and there is a curved transparent belt ("New Moon").

2 If the gas further enters the inner capsule, a liquid level appears, and two arc shadows ("double bow sign") representing the inner capsule and the outer capsule are seen above the gas.

3 When the internal capsule ruptures and collapses, the collapsed inner capsule floats on the liquid surface, and irregular shadows can be seen on the liquid surface of the capsule ("water floating lotus sign").

If the cyst is ruptured, the contents are coughed and there is no infection. The chest radiograph is characterized by a thin wall with a smooth edge containing a balloon swelling. After the capsule cavity is gradually reduced, only some fibrotic shadows are left, such as infection after the cyst is broken. The wall is thickened, and there are visible lung infiltrates with chronic inflammation, such as ruptured into the chest, pleural effusion or liquid pneumothorax.

12. CT or B-ultrasound can be seen that the separation structure in the capsule is characterized by active cysts, the lung image is a circular mass, CT confirms that the mass is filled with liquid, and the positive rate of serological examination of hepatic hedding cysticercosis Low, according to the pathological morphology of the hydatid cyst and the imaging features of the complication, combined with clinical pathological classification and classified into 5 types:

(1) Single hair style: Because the hydatid cyst is filled with water-like cyst fluid, the B-ultrasound, CT and MRI images are neatly edged, showing a round or oval rounded liquid occupying shadow, which has a clear boundary and uniform density. , the size is not equal, generally 2 ~ 8cm, more common in the right side and double lower lung, the difference between the wall of the hydatid cyst and the density of lung tissue, and the boundary is distinct, smooth wall, in the larger hydatid cyst There is a potential gap interface between the outer and outer capsule walls, and a double wall sign can occur.

(2) Multiple hair styles: Two or more images of hydatid cysts were found in the lungs, with lung tissue or hydatid cyst wall separated.

(3) calcification type: a hydatid cyst with a long course of disease, the outer capsule is thick and rough with calcium salt deposition, or even complete calcification, the hydatid cyst has been degenerated and necrotic, the cystic fluid is purulent, and the hydatid cyst density is high. Uneven, the wall thickness of the capsule is irregular, with wide sound shadow and side wall sound shadow, CT and MRI show shell edge, CT value>60HU.

(4) Infected type: secondary infection of the hydatid cyst into pus, due to cyst and part of the cystic necrosis collapse, mixed in the pus, the density increased, the necrotic tissue contained floc or patchy uneven After the shadow and CT enhancement, the CT value of the tissues surrounding the hydatid cyst increased and the hydatid cyst did not increase.

(5) Rupture type:

1 The outer capsule ruptures and communicates with the bronchus, a small amount of air enters into the inner and outer sacs, forming a star-moon translucent shadow;

2 The inner and outer sacs are ruptured at the same time and communicate with the bronchial tubes. When the air enters the inner and outer sacs, a liquid level appears, and a translucent band of double-layer arc is present above it. This sign has diagnostic value;

3 The inner and outer capsules are completely ruptured, the inner capsule collapses, and floats on the liquid level, making the gas-liquid surface uneven. For example, water floating lotus is also called water floating lotus sign. This sign is a typical CT of hydatid cyst rupture. which performed;

4 If the liquid part of the capsule is coughed out, the cystic space is reduced, and the CT value is high when the capsule wall is folded, and it is difficult to distinguish it from the substantial mass in the lung. If the contents of the capsule are completely coughed, a spherical thin wall can be formed. Cavity

5 pulmonary hydatid cysts after infection with cystic wall thickening, such as bronchopleural fistula, can cause liquid pneumothorax, but also due to infection to form empyema or pus pneumothorax; 6 lung outwife cyst, CT found pulmonary hydatid Cysts are very helpful for diagnosis. For pulmonary hydatid cysts, chest puncture is contraindicated as a diagnostic method, because puncture can cause extravasation of cystic fluid and produce serious complications such as hypersensitivity or hydatid cyst spreading.

Diagnosis and identification of pulmonary hydatid disease

Diagnostic criteria

Most patients have no obvious positive signs, and there are voiced sounds in the percussive area, and the breath sounds are reduced or disappeared. The larger cysts can compress the mediastinum, shifting the trachea and heart, and may have thoracic deformities in children with pleurisy or empyema. There are corresponding signs.

Mainly based on:

1 has lived in popular areas, with a history of contact with animals such as dogs and sheep.

2 X-ray findings of hydatidosis are more typical, with single or multiple marginal cystic shadows.

3 laboratory tests: eosinophils increase, often 5% to 10%, and even up to 20% to 30%, direct counting (0.15 ~ 0.3) × 109 / L, sometimes cough or chest water can be found Cyst fragments and sacs, head sections or small hooks,

4 Other diagnostic methods include the echinococcal intradermal test (Casoni test), the hydatid complement test, the indirect hemagglutination test and other immunization methods. Currently, there are typical cystic liver images, but seronegative patients, in the lungs. Block shadows are taken by biopsy or cytology by percutaneous or bronchoscopy under X-ray or ultrasound guidance, but it should be noted that cysts are suspected to be cysts of hydatid cysts, so as not to cause cystic fluid to overflow and produce allergic reactions. Or the original head sputum leakage caused serious complications such as the spread of hydatid disease.

Differential diagnosis

The disease should be differentiated from a variety of chest diseases in clinical or chest X-ray manifestations, and it is difficult to identify with gas-liquid pulmonary cysts. The infection should be differentiated from lung abscess, inflammation, aspergillosis, and intrapulmonary hematoma. Including pulmonary traumatic hematoma and postoperative hematoma, clinical history of chest trauma, such as careful analysis, combined with clinical history, careful observation of the characteristics of the lesion can make a correct diagnosis, complications in the rupture of the cyst, clinical and X-ray performance is complex Misdiagnosis, the disease to be identified is pulmonary cyst, lung cancer, lung metastases, lung abscess, tuberculosis, mediastinal tumor, effusion caused by various diseases of the chest and pericardial cysts, etc. Most of the above diseases require surgical treatment, differential diagnosis Unclear should be open for exploration.

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