Pulmonary hydatid disease

　　The definitive host of the Echinococcus granulosus. The adult worm lives in the dog's small intestine, and the eggs are excreted with feces, contaminating food. After humans (or sheep, pigs, cattle) eat the food, the eggshell is digested by gastric juice in the upper digestive tract and hatches into larvae, i.e., oncospheres, which then pass through the intestinal mucosa into the blood, reaching the portal venous system (mesentery, omentum, and liver). Most oncospheres remain in the liver (about 75% to 80%), with a few oncospheres passing through the liver into the small circulation to the lung (about 8% to 15%) and other organs such as mesentery, omentum, spleen, pelvic cavity, muscle, and subcutaneous tissue.

　　After the oncosphere enters the lung, it gradually develops into a hydatid cyst, growing to about 1 to 2 cm in about half a year. Due to the loose lung tissue, rich blood circulation, and negative pressure attraction of the pleural cavity, the growth rate of the oncosphere in the lung is faster than in the liver and kidney, increasing to 1 to 2 times the original volume per year on average, reaching about 2 to 6 cm, with the largest cysts reaching 20 cm and the weight of the cyst fluid exceeding 3000g. The hydatid cyst contains an outer cyst and an inner cyst. The inner cyst is the inherent cyst wall of the hydatid cyst, with a thickness of only 1mm but a pressure as high as 13.3 to 40kPa (100 to 300mmHg), making it prone to rupture. The inner cyst can be further divided into an inner and an outer layer, with the inner layer being the germinative layer, very thin, secreting colorless and transparent cyst fluid, producing many daughter cysts and scolexes, which, if shed into the cyst cavity, become hydatid sand. The outer layer is cell-free, multi-layered, semi-transparent, milky white, and elastic, resembling skin powder in appearance. The outer cyst is a fibrous encapsulation formed by the human body's reaction to the inner cyst, surrounding the entire inner cyst and being about 3 to 5mm thick. The space between the inner and outer cysts is potential, containing no fluid or gas, and is not adherent.

　　80% of hydatid cysts are peripheral, with more in the right lung than in the left, and more in the lower lobe than in the upper lobe. The blood flow in the right lung is slightly more, and it is relatively close to the liver, with a rich network of lymphatic vessels connecting the two, which may be the reason why the right lung is more common. Most cysts are solitary, accounting for 65% to 75%, and multiple cases are generally 2 to 3, on one or both sides. About 17% to 22% have concurrent cysts in other locations, with lung and liver involvement being the most common, accounting for 13% to 18%.

　　1. Allergic reactions and the transmission of echinococcosis

　　Echinococcal cyst rupture due to various reasons can cause secondary echinococcal infection. Since the contents of the cyst are relatively foreign to the body, they can cause allergic reactions such as urticaria, asthma, and increased eosinophils. If a large amount of cyst fluid enters the blood circulation, severe allergic shock may occur, even death.

　　2. Fistula between lung echinococcal cysts, bile duct, and bronchus

　　Cysts that have been infected or ruptured can be complicated with pleural or mediastinal abscesses or empyema, and after the rupture of liver echinococcal cysts, they may communicate with the pleural cavity or lung and bronchus, forming a fistula between lung echinococcal cysts, bile duct, and bronchus.

　　3. When the echinococcal cyst in the lung breaks into the bronchus, a large amount of fluid and broken cyst skin may be coughed up.

　　According to the analysis of a large group of cases from 1950 to 1985 in China, lung echinococcosis accounts for 14.81% (2408/16258) of human echinococcosis, with more males than females (about 2:1), children accounting for 25% to 30%, and most people under the age of 40. The minimum age is 1 to 2 years, and the maximum age is 60 to 70 years.

　　The interval from infection to the appearance of symptoms is generally 3 to 4 years, even up to one or twenty years. Symptoms vary due to the size, number, location, and presence of complications of the cysts. Early cysts are small and generally have no obvious symptoms, often discovered during physical examination or during chest X-ray for other diseases. When the cysts increase in size and cause compression or inflammation, symptoms such as cough, sputum, chest pain, and hemoptysis may occur. Large cysts or those near the hilum of the lung may cause dyspnea. If the esophagus is compressed, there may be difficulty in swallowing. On the side, the cysts at the apex of the lung may compress the brachial plexus and cervical sympathetic ganglion, causing Pancoast syndrome (shoulder and arm pain on the affected side) and Horner syndrome (one eyelid drooping, skin erythema without sweating). If the cyst breaks into the bronchus, and the amount of cyst fluid is large, there is a risk of asphyxiation, and the daughter cysts and oncospheres may overflow, forming multiple new cysts. Patients often have allergic reactions, such as skin erythema, urticaria, and wheezing, and severe cases may shock. Cysts that rupture and become infected may have symptoms of pulmonary inflammation and empyema, such as fever and yellow sputum. A few cysts may break into the pleural cavity, causing fever, chest pain, shortness of breath, and allergic reactions.

　　Most patients have no obvious positive signs. Larger cysts can cause mediastinal displacement, and children may have chest deformities.叩诊患侧浊音，呼吸弱，those with pleurisy or empyema have corresponding signs.

 How to prevent the lung echinococcosis?

The main points for the prevention of this disease are as follows:

1. Conduct health education in epidemic areas, investigate and treat patients, train professionals, establish prevention and treatment institutions, and carry out prevention and treatment monitoring and scientific research.

2. Strictly control the source of infection, rationally handle sick animals and their internal organs, advocate deep burial or incineration, and regularly deworm domestic and pastoral dogs, kill wild carnivorous animals around pastures, and eliminate the source of infection.

3. Strengthen personal protection, establish good hygiene habits, do not eat unclean leafy vegetables, do not drink unboiled water, and wash hands frequently.

4. Currently, surgical treatment remains the main method for echinococcosis, and attention should be paid to prevent secondary infection and anaphylactic shock during surgery.

　　1. Chest X-ray examination is the main diagnostic method for echinococcosis. In areas where the disease is prevalent and there is a history of contact, most cases can be diagnosed based on chest X-rays alone. Early cysts with a diameter of less than 1cm show indistinct inflammatory shadows, those with a diameter greater than 2cm show clear, sharp, ovoid shadows with even density and slightly lighter than the density of the heart and solid tumors. When it can be diagnosed clearly, it is about 6 to 10cm, and the density is close to that of solid tumors, usually solitary, but also multiple. As fluid-filled cysts, when standing and inhaling, the diaphragm descends slightly, and the head and foot diameters increase slightly. When exhaling and the diaphragm rises, the transverse diameter is slightly longer and the upper and lower diameters are slightly shorter (‘echinococcus respiratory sign’). Large cysts can be lobulated or multiringed. The cysts in the lower lung field ‘sit’ on the diaphragm, causing the diaphragm to descend or even be concave. Sometimes, artificial pneumoperitoneum is needed to push the mediastinum to the opposite side. The mediastinum affected in the lower lobe is less, while the large cysts at the top of the right liver cause the heart to shift to the left, which is helpful for differential diagnosis. A few cases have atelectasis and pleurisy.

　　2. Laboratory examination: eosinophil count increases, usually around 5% to 10%, even up to 20% to 30%, directly 0.15 to 0.3) × 10^9/L. Sometimes, fragments of cysts, heads, or small hooks can be found in the expectoration or pleural effusion.

　　3. Other diagnostic methods include Casoni test (echinococcus intradermal test), complement fixation test for echinococcus, indirect hemagglutination test, and other immunological methods.

　　Postoperative food therapy for echinococcosis

　　1. Ginkgo and duck stewed white ginkgo seeds 200g. One white duck. Peel and boil the white ginkgo seeds in boiling water, then peel and remove the kernel, blanch in boiling water again and mix with the duck meat that has been deboned and cooked. Add clear soup, steam for 2 hours until the duck meat is tender, then eat.

　　2. Schisandra berries stewed with meat 50g schisandra berries, duck meat or lean pork in appropriate quantity. Steam or stew the schisandra berries with the meat, and add appropriate seasoning. Take the meat, medicine, and soup together.

　　3. Lily chicken with lily root 15g, chicken or duck, pork in appropriate quantity. Simmer the lily root and meat together until cooked, then add appropriate seasonings. Take regularly.

　　4. Decorticated melon seed and broad bean soup.

　　1. Traditional Chinese medicine treatment for pulmonary echinococcosis

　　Echinococcus toxicity in the lung and chest causes chest swelling and pain, expectoration with blood, fatigue, night sweats, or fever, expectoration of sputum with pus, or pleural effusion. Tongue fur is greasy, pulse is wiry and slippery.

　　1. Treatment method:Open chest and resolve phlegm, reinforce the body and expel pathogenic factors.

　　2. Prescription:Guided expectoration decoction with modification: Salvia miltiorrhiza 30g, Astragalus membranaceus 13g, Artemisia annua 12g, Trionycium 13g, Scutellaria baicalensis 12g, Platycodon grandiflorus 45g, Citrus reticulata 45g, Semen pinellae 45g, Poria 13g, Bupleurum chinense 7g, Fructus aurantii 12g, Glycyrrhiza uralensis 6g, Mylabris powder 12g (to be decocted). If there is fever, expectoration of purulent sputum, add Arundo donax 30g, Benincasa hispida 12g, Houttuynia cordata 13g, for pleural effusion add Semen descurainiae 4g, 6 dates.

　　2. Western medical treatment for pulmonary echinococcosis

　　Surgical method:

　　1. Enucleation of the internal capsule:After separating adhesions in the chest, as the cysts are often near the periphery, the lung surface sometimes shows a fibrous protein layer covering it. Fill the surrounding lung with gauze before removal, leaving only the site prepared for the incision to take the cyst exposed, and prepare an attractive aspirator with strong suction, which is convenient for quickly aspirating the contents of the cyst cavity in case of accidental rupture, to avoid contamination of the pleural cavity. Then carefully cut the lung fibrous layer surrounding the cyst, tilt the knife slightly to avoid directly cutting into the inner cyst. Because the inner cyst has high pressure, after cutting a small opening in the outer cyst, the white inner cyst wall can be seen to bulge out from the incision. Extend the incision, and ask the anesthetist to blow air forcefully through the tracheal tube, using the lung pressure to push out the inner cyst cavity. Generally, as there is no adhesion between the inner and outer cysts, the cyst cavity can be completely removed. After the inner cyst is removed, there is leakage from the fine bronchial orifices on the outer cyst, which should be blocked with gauze first, and then sutured and repaired. The residual cavity wall with more can be excised or inverted, and then sutured, completely eliminating the cavity.

　　2. Intracyst puncture resection:Wipe the surrounding area of the cyst with gauze or rinse with hydrogen peroxide to kill the protoscoleces. In the past, formalin was often used to paint, which had the potential to cause severe bronchospasm through the bronchial leakage, and it is now no longer used. Each bronchial leakage in the cavity should be sutured one by one, and then sutured from the periphery to the bottom in full thickness (for larger ones, they can be sutured in stages), to eliminate the cavity.

　　3. Lung resection:Used for patients with cyst rupture, severe infection of lung tissue, concurrent bronchial expansion, pulmonary fibrosis, empyema, bronchopleural fistula, or lung cancer that cannot be excluded. If possible during surgery, it is best to first free the bronchus, clamp it, and avoid the cyst cavity bursting into the bronchus when compressing the lung tissue during the operation, causing the spread of the disease or death from asphyxiation.

　　4. Management of special types of echinococcosis:If there are liver and lung cysts at the same time, they can be operated on in one operation. The side with larger lesions or complications should be treated first if there are bilateral lesions, and if there is a bronchopleural fistula in the lung cyst, it should be drained first, and then lung resection should be performed after the infection is controlled and physical strength is restored.

　　Treatment results: Qian Zhongxi reported in 1979 that the mortality rate of chest surgery was 0.9%, and there have been no deaths in recent years, with good surgical results. Some cases have recurred, and the reasons are:

　　(1) Small hydatid cysts left in the operation.

　　(2) Extravasation of interoperative cyst fluid, head segment shedding, recurrence after transplantation.

　　(3) Re-infection, recurrence of patients with resection of the lung, the effect is also mostly good.