Overview
Lung encapsulation disease, also known as lung encapsulated cysts, lung echinococcosis, lung echinococcus cysts, for fine-grained echinococcus tapeworm (canine tapeworm) larvae (echinococcus larvae) parasitized in the lungs due to the lungs, is the lungs of the more common parasitic diseases, zoonotic. The disease is most common in animal husbandry areas, China is mainly distributed in Gansu, Xinjiang, Ningxia, Qinghai, Inner Mongolia, Tibet and other provinces and regions.
Causes
The final host of Echinococcus granulosus is carnivores such as dogs, wolves and jackals, and the intermediate host is even-toed ungulates such as sheep, cattle, camels, pigs and deer. Adult tapeworms are parasitized in the small intestine of dogs, and the eggs are excreted in feces and then contaminate the food. After feeding in humans (or sheep, pigs, and cattle), the egg shells are digested by gastric juices in the upper gastrointestinal tract and hatch into larvae, i.e., hexacoccid larvae, which then pass through the mucous membranes of the digestive tract into the bloodstream to the portal system (mesentery, greater omentum, and liver), and most larvae are retained in the liver a few hexacoccid larvae pass through the liver into the minor circulation to the lungs and other organs, such as mesentery, omentum, Spleen, pelvis, muscles, subcutaneous tissues, etc.
Six hooked larvae into the lungs, gradually developed into cysts, about six months to grow to 1 ~ 2cm, due to the lung tissue laxity, rich blood circulation and negative pressure in the chest cavity attraction and other factors, six hooked larvae in the lungs in the growth of faster than in the liver and kidney, on average, the average annual growth to the original volume of 1 ~ 2 times, up to 2 ~ 6cm or so, cysts can be up to the largest 20cm, the cystic fluid weighs more than 3,000g. The cyst contains outer and inner sacs, the inner sac is the intrinsic cyst wall of the cyst, the thickness is only 1mm, but the pressure is as high as 13.3-40kPa, easy to break; the inner sac can be divided into the inner and outer layers, the inner layer is the germ layer, very thin, secretes colorless transparent cystic fluid, produces a lot of cysts and parasitic head nodes, such as shedding in the cystic cavity, that is, it will become a sand of the worms, the outer layer of the non-cellular, multilayered, semi-transparent, milky white, with the elasticity, appearance similar to powdered skin; the outer capsule is a layer of fibrous envelope formed by the reaction of human tissues to the inner capsule, encircling the entire inner capsule, about 3 to 5 mm thick, between the inner and outer capsule is a potential lumen, no liquid and gas, and no adhesion.
Symptoms
The interval from infection to the appearance of symptoms is usually 3 to 4 years, or even 10 to 20 years. Symptoms vary according to the size, number, location of the cyst and the presence or absence of complications. In the early stage, the cyst is small and usually has no obvious symptoms, and is often found by physical examination or during chest X-ray for other diseases. When the cysts increase in size and cause compression or inflammation, there are symptoms such as cough, sputum, chest pain and hemoptysis. If the cyst is huge or located near the pulmonary hilum, there may be dyspnea. If the esophagus is compressed, there is dysphagia. Occasionally, apical cysts compress the brachial plexus and cervical sympathetic ganglion, causing Pancoast’s syndrome (pain in the shoulder and arm on the affected side) and Horner’s sign (drooping eyelids on one side, flushed skin without sweating). If the cyst breaks into the bronchus, there is a danger of asphyxiation if there is a large amount of cystic fluid, and the subcapsules and cephalic ganglia spill out, which can form several new cysts. Patients often have allergic reactions, such as skin flushing, urticaria and wheezing, and in severe cases, shock can occur. If the cyst ruptures and becomes infected, there are symptoms of lung inflammation and lung abscess such as fever and coughing up yellow sputum. A few cysts that break into the chest cavity have fever, chest pain and shortness of breath and allergic reactions.
Most patients do not have obvious positive signs. Larger cysts may lead to mediastinal displacement, and in children, thoracic deformity may occur. Turbidity of percussion on the affected side, weak respiration, and signs of pleurisy or pyothorax are present.
Examination
1. Chest X-ray examination
It is the main diagnostic method for encapsulated disease. In the early stage of cysts with a diameter of less than 1cm, only inflammatory shadows with fuzzy edges can be seen; those with a diameter of more than 2cm have clear outlines, sharp edges and round-like shadows, with a uniform and slightly pale density. The density is lower than that of the heart and substantial tumor, and it has been about 6-10cm when it can be clearly diagnosed, and the density is close to that of the substantial tumor, which is usually single, and there are also multiple ones, which are fluid-containing cysts. When the diaphragm is descending during inspiration, the head and foot diameters are slightly increased; when the diaphragm is rising during expiration, the transverse diameters are slightly longer and slightly shorter (“worm respiratory sign”), and the large cysts can be lobulated or polycyclic, and the cysts in the lower lung field “sit” on the diaphragm, which makes the diaphragm position fall and even concave, sometimes requiring manual operation. The cyst in the lower lung field “sits” on the diaphragm, causing the diaphragm to drop and even sink, sometimes requiring an artificial pneumoperitoneum to push the mediastinum to the opposite side.
2.Laboratory examination
Eosinophilic granulocytes are increased, often around 5%~10%, even up to 20%~30%, up to (0.15~0.3)×109/L. Sometimes cystic fragments and sacs, head nodes or small hooks can be detected in coughing up material or pleural fluid.
3.Other tests
Including intradermal test for encapsulated worms (Casoni test), complement binding test for encapsulated worms, indirect blood agglutination test and other immunological methods.
Diagnosis
Diagnosis can be made on the basis of history, clinical symptoms and auxiliary examination.
Treatment
1. Drug treatment
At present, there are mebendazole and prothiabendazole, which have the effect of degrading and deteriorating the hair layer and protozoa, and some curative effects can be seen clinically, the symptoms are improved, and some of the cysts stop growing or decrease in size. There is also praziquantel, which is not clinically effective or can be applied preoperatively to minimize postoperative recurrence. Currently, drug therapy is only used for patients with multiple cysts that are inoperable.
2. Surgery
Surgery is the main treatment method, and there are 2 kinds of cyst removal and lobectomy. Depending on the size of the cysts, the number of cysts, the location of the cysts, the presence or absence of concurrent infections, and the presence or absence of pleural adhesions, the surgical method will be decided. Intraoperative care should be taken to prevent rupture of the cyst and spillage of cystic fluid into the chest cavity or soft tissues of the chest wall, so as not to cause dissemination of cystic lesions or allergic reactions.
(1) Complete removal of the internal capsule After opening the chest to separate the adhesions, because the cysts are mostly in the near periphery, the covering fibrin layer can sometimes be seen on the lung surface. Before removal, the lungs should be covered with gauze, only the part of the cyst that is ready to be incised should be exposed, and a suction device with strong suction should be prepared to facilitate timely suctioning out of the contents when the cyst cavity ruptures accidentally to avoid contamination of the thoracic cavity.
(2) Endocyst removal by puncture Apply gauze around the cyst site or rinse with hydrogen peroxide to kill the protocephalic larvae. The residual cavity with bronchial leakage should be sutured one by one, and then the whole layer from the periphery to the bottom (larger ones can be divided into several times) should be sutured to eliminate the residual cavity.
(3) Lung resection is used in patients with ruptured cysts, severe infection of the lung tissue, complicated by bronchodilatation, pulmonary fibrosis, pyothorax, bronchopleural fistula or lung cancer. If possible during the operation, it is best to free the bronchus first and clamp it to avoid the cyst cavity breaking to the bronchus when squeezing the lung tissues during the operation, causing the spread of lesions or death by suffocation.
(4) Surgical management of special types of cysticercosis, such as liver and lung cysts at the same time, can be operated at once. If there are lesions on both sides, first deal with the side with larger lesions or complications, and if there is bronchopleural fistula in lung cysts, closed drainage should be performed first, and then lung resection should be carried out after the infection is controlled and the strength is recovered.