【正文】 酸性粒細(xì)胞浸潤(rùn)，并逐漸長(zhǎng)成棘球蚴的囊狀體，有的可形成巨大的囊腫 ? 包蟲囊腫的壁分為兩層，外層為角質(zhì)層，較堅(jiān)韌，起保護(hù)和營(yíng)養(yǎng)胚層的作用；內(nèi)層為胚層（或稱為生發(fā)層），能分泌液體，具有繁殖作用，液體內(nèi)有毛鉤和頭節(jié)，頭節(jié)脫落則形成子囊 ? 囊腫破裂，囊液溢出，頭節(jié)可在鄰近形成新的囊腫 ? 肺包蟲囊腫可破入支氣管及繼發(fā)感染 31 癥狀 ? 咳嗽、咯血、胸痛及發(fā)熱 ? 破入胸腔引起氣胸和胸腔積液 ? 破入支氣管時(shí)咳出大量囊液 ? 較小的包蟲囊腫可無癥狀 ? 嗜酸性粒細(xì)胞增多 ? 皮試及血清學(xué)試驗(yàn)有助診斷 32 X線 ? 單發(fā)或多發(fā)的圓形或類圓形影， 1～ 10cm ? 密度均勻，囊狀，邊緣光滑清楚，可環(huán)形鈣化 ? 外囊破裂，并與支氣管相通，少量氣體進(jìn)入內(nèi)外囊之間，在囊腫上部形成新月形透亮影 ? 內(nèi)外囊同時(shí)破裂，并與支氣管相通，部分囊內(nèi)的內(nèi)容物咳出，空氣進(jìn)入囊內(nèi)形成氣液平面 ? 內(nèi)外囊同時(shí)破裂后，若內(nèi)囊塌陷，漂浮于液平面上形成凹凸不平的形態(tài)，稱為 “ 水上浮蓮 ” 征 ? 肺表面的囊腫破裂可形成氣胸或液氣胸 33 CT ? 囊腫 1cm以下時(shí)，邊緣模糊的片狀影。 ≥ 2cm，輪廓清楚的類圓形囊性影，分葉狀。邊緣光整，密度均勻， CT值為液體密度 ? 囊壁薄厚不一，囊腫與胸膜或縱隔相鄰處變平 ? 囊腫衰老呈不規(guī)則狀，似實(shí)質(zhì)性腫瘤，但密度仍較低 ? 合并感染時(shí)邊緣模糊，類似肺膿腫 ? 破裂可形成支氣管瘺，咳出部分囊液且空氣進(jìn)入囊內(nèi)后出現(xiàn)氣液面 ? 破入支氣管后，若外囊有細(xì)小裂口而內(nèi)囊未破，可有少量氣體進(jìn)入內(nèi)外囊之間，呈現(xiàn)新月形或鐮刀狀氣體影 ? 空氣進(jìn)入外囊內(nèi)，內(nèi)囊塌陷并漂浮于液面， “ 水上浮蓮征 ” 34 Life Cycle of E granulosus ? The definitive host is usually a dog (or other carnivore) ? The adult worm lives in the proximal small bowel of the definitive host, attached by hooklets to the mucosa ? Eggs are released into the host39。s intestine and excreted in the feces ? Sheep are the most mon intermediate hosts. They ingest the ovum while grazing on contaminated ground ? The ovum loses its protective chitinous layer as it is digested in the duodenum ? The released hexacanth embryo, or oncosphere, passes through the intestinal wall into the portal circulation and develops into a cyst within the liver 35 Life Cycle of E granulosus ? When the definitive host eats the viscera of the intermediate host, the cycle is pleted ? Humans may bee intermediate hosts through contact with a definitive host (usually a domesticated dog) or ingestion of contaminated water or vegetables ? Once in the human liver, cysts grow to 1 cm during the first 6 months and 2–3 cm annually thereafter, depending on host tissue resistance 36 Life cycle (dogsheep cycle) of E granulosus ? Diagram shows the most prevalent life cycle of E granulosus, in which a dog and sheep serve as the definitive and intermediate hosts, respectively 37 Three layers Outer pericyst, posed of modified host cells that form a dense and fibrous protective zone Middle laminated membrane, is acellular and allows the passage of nutrients Inner germinal layer, the scolices (the larval stage of the parasite) and the laminated membrane are produced Middle laminated membrane and the germinal layer form the true wall of the cyst 38 Hydatid Cyst Structure ? Daughter vesicles (brood capsules) are small spheres that contain the protoscolices and are formed from rests of the germinal layer ? Before being daughter cysts, these daughter vesicles are attached by a pedicle to the germinal layer of the mother cyst ? At gross examination, the vesicles resemble a bunch of grapes ? Daughter cysts may grow through the wall of the mother cyst, particularly in bone disease 39 Multivesicular cyst ? Photograph of a human kidney ? be sectioned along the midcoronal plane ? A large cyst with the typical bunch of grapes appearance due to daughter cysts ? (→ ) ureter 40 Hydatid Cyst ? Cyst fluid is clear or pale yellow, has a neutral pH, and contains sodium chloride, proteins, glucose, ions, lipids, and polysaccharides ? The fluid is antigenic and may also contain scolices and hooklets ? When vesicles rupture within the cyst, scolices pass into the cyst fluid and form a white sediment known as hydatid sand 41 Hydatid Disease in humans ? Once the parasite passes through the intestinal wall to reach the portal venous system or lymphatic system, the liver acts as the first line of defense and is therefore the most frequently involved an ? Hydatid disease involves the liver in 75% of cases, the lung in 15%, and other ans in 10% ? The lungs are the second most frequent site of hematogenous spread in adults and probably the most mon site in children 42 Hematogenous Dissemination ? Compressible ans such as the lung or brain facilitate the growth of the cyst ? Most cysts are acquired in childhood, remain asymptomatic for a long period of time, and are later diagnosed incidentally at chest radiography ? Cysts are multiple in 30% of cases, bilateral in 20%, and located in the lower lobes in 60% ? Calcification in pulmonary cysts is very rare, although it may be seen in pericardial, pleural, and mediastinal cysts 43 Pulmonary hydatid cyst ? M3 ? A wellcircumscribed, masslike lesion with a polycyclic configuration in the left lower lobe ? There is obliteration of the left costophrenic angle 44 Pulmonary hydatid cyst ? Sudden coughing attacks, hemoptysis, and chest pain are the most mon symptoms ? After cyst rupture, expectoration of cyst fluid, membranes, and scolices may occur ? Rupture into the pleural cavity may occur ? Bacterial infection of the cyst is the most serious plication monly seen after rupture 45 Pulmonary hydatid cyst ? Welldefined masses, usually round, peripheral cysts may be oval or polycyclic ? Air collection appears as a thin, radiolucent crescent in the upper part of the cyst and is known as the crescent sign or meniscus sign ? As air continues to enter this space, the two layers separate pletely and the cyst shrinks and ruptures, allowing the passage of air into the endocyst 46 Pulmonary hydatid cyst ? An airfluid level inside the endocyst and air between the pericyst and the endocyst with an onion peel appearance constitute the Cumbo sign ? After partial expectoration of the cyst fluid and scolices, the cyst empties and the collapsed membranes can be seen inside the cyst (serpent sign). When it has pletely collapsed, the crumpled endocyst floats freely in the cyst fluid (water lily sign) ? If the fluid is entirely evacuated by expectoration, the remaining solid pon