Hydatid cyst

“ It has been generally assumed that echinococcus fluid contains a toxic substance the escape of which into the body cavity (at operation or by bursting of a hydatid cyst) produces more or less severe symptoms (fever, peritonitis, urticaria) , so much so that one speaks of hydatid intoxication. The investigations of Kobert, Joest, etc., have, however, shown the harmlessness of fresh undecomposed hydatid and cysticercus fluid for rabbits, mice and guinea-pigs, whether inoculated intraperitoneally, subcutaneously or intravenously. ”

“ They are common in the lungs, kidneys, spleen, omentum, and subperitoneal tissue of the abdominal walls. They are less common in the heart, brain, spinal canal, the pelvic viscera, and the bones. Mostly but a single tumor is found in the same person, but occasionally several occur together in the same or in different organs.
There are several varieties of the hydatid tumor. In man the more common form consists of a cyst or a group of cysts enclosed in a connective-tissue envelope induced by the presence of the parasite. ”

“ Suppurating hydatid cyst which may be confused with liver abscess is most surely differentiated by finding echinococcus hooklets.
Then too the complement fixation test for hydatid disease will differentiate.
Tuberculosis is often thought of, particularly when a liver abscess ruptures through the lungs. Malaria is also usually suspected. Abscess in the kidney or perinephritic region may be very confusing. In an abscess of the abdominal wall an exploring needle does not move up and down with respiration as it does when penetrating a liver abscess cavity. ”

“ A hydatid cyst might counterfeit a hydro-nephrosis, but instances of this affection having its primary seat in the kidney are of extreme rarity. An ordinary cystic kidney is most likely to be connected with chronic diffuse interstitial nephritis, which will have made itself manifest by the usual symptoms, and is moreover unlikely to attain the dimensions of a large or even moderate hydro-nephrosis. In a thin person the ureter might, if felt dilated through the abdominal walls, clear up the diagnosis. ”

“ A phthisical appearance is possible, with deterioration of the blood-crasis and progressive loss of flesh. Marked clubbing of the finger-ends and incurvation of the nails have been noticed, all of which symptoms have disappeared after the hydatid cyst has been tapped or expectorated. Cough nearly always accompanies this disease, as it does a large pleural effusion. The expectoration is a glairy mucus, sometimes stained with blood; when local bronchitis occurs as a complication, it may become muco-purulent. ”

“ The nurses develop from little round six-hooked embryos in a more or less complicated fashion as so-called 'bladder-worms.' The latter inhabit very diverse, but usually parenchymatous, organs of the higher and lower animals, and are thence passively transferred to the intestine of their subsequent host" (Leuckart, 1, [1] p. 270) .
Historical Sketch.—Certain forms of Cestodes have been known from time immemorial. The hydatid cyst is alluded to by early medical writers, and Aristotle speaks of examining the tongue of pigs to ascertain the presence of bladder-worms. ”

“ A moderate-sized needle, slightly curved and filled with thread, is now passed through the exposed portion of the cyst, and the thread allowed to remain. The fluid is thus permitted slowly to escape, and at the same time the sac becomes collapsed, after which it is easily removed by pulling gently at the thread with which it is connected. As good a hold should be taken with the string as possible, and all the water should be allowed to flow out before any attempt is made to extract the remains of the hydatid. ”

“ The tendency of the treatment of hydatid cysts has constantly been toward simplicity, and the success occurs in a direct ratio thereto. In forming an estimate of the relative value of the methods of treatment, the average of mortality of each plan becomes the most important factor. Simple tapping and paracentesis, the most frequently adopted mode of treatment, is not without immediate and remote danger. ”

“ The cystic form of the dog’s tape-worm (echinococcus) is a most dangerous parasite for man. When the egg of the dog’s tape-worm is swallowed by man, the embryo escaping from this egg burrows from the alimentary canal, and forms large cysts, chiefly in the liver, but occasionally in the lungs, brain, and other organs. For the removal of these, surgical interference is required. This form of cyst is commonly known as a hydatid. ”

“ This thrill is not often obtainable, and in any case is not pathognomonic of hydatids, as it may be elicited in ascites and in other abdominal cysts. Pressure of the cyst upon adjacent structures, and the occurrence of suppuration, are attended with characteristic clinical features.
The diagnosis of hydatids will be considered with the individual organs. The disease is more common in certain parts of Australia and in Shetland and Iceland than in countries where the association of dogs in the domestic life of the inhabitants is less intimate. ”

“ In the same way paracentesis removes doubt whether there be mediastinal tumor, solid tumor of the lung, or circumscribed pneumonic abscess; in the latter the general history of each case is helpful. From phthisis we must have recourse to the physical diagnosis already mentioned as belonging to hydatids. An unbroken cyst in the liver, high up and far back on its convex surface, may not be distinguishable from one in the base of the lung immediately over the liver or one in the cavity of the pleura. ”

“ The fluid is generally glairy, sometimes thick and gelatinous, often turbid and dark coloured. Not unfrequently the main cyst is subdivided, either by membranous septa, or by an aggregation of smaller cysts of the nature of hydatids. The swelling is at first on one side, and gradually rises out of the pelvis; often it remains long moveable; it increases, becomes more fixed, and ultimately fills the abdomen, displacing the viscera, and giving rise to feelings of much uneasiness, deformity, and loss of health. ”

“ In the museum of the Royal Veterinary College there are a number of excellent preparations of true hydatids taken from various animals, especially from cattle, swine, and sheep; and there are also many kinds of bladder worms which, though often called “hydatid” by veterinarians, have a totally different origin from that of the true Echinococci. The so-called gid-hydatids (Cœnuri) and slender-necked hydatids (Cysticercus tenuicollis) are of this description. ”

“ A little bladder-like body, not larger than a pea, is often found hanging by a thread-like stalk from one of the fimbriæ of the oviduct. It is a relic of foetal life, being probably the remains of the Wolffian body, and sometimes goes by the name of the hydatid or vesicle of Morgagni. The walls are very thin and covered by peritoneum. What rôle these vesicles play in the economy is uncertain, but they have been found to undergo cystic degeneration. They rarely attain to a size larger than that of an orange, and then either remain stationary or else burst. ”

“ Each set of parasites freely communicated with the knee-joint, necessitating amputation of the limb.
The very large museum connected with Guy’s Hospital is rich in hydatids. When, some time ago, I spent several days in going over the collection, I examined seventy-six preparations, representing apparently seventy separate cases of this affection. Amongst the noteworthy specimens one lung hydatid was intimately associated with a thoracic aneurism, two others being connected with the pleura ”

“ The exogenous and endogenous hydatids may coexist in the same bearer. In the lower animals we commonly find the organs of the body occupied by numerous lobulated cysts, varying in size from a walnut to a goose’s egg, but sometimes rather larger. They are rarely solitary, being particularly liable to occupy both the liver and lungs in the same animal. The viscera are sometimes crowded with cysts. The hydatids do not usually protrude much beyond the surface of the infested organ, but lie imbedded within its parenchymatous substance. ”

“ It is very evident when the collections are formed near the convexity of the glands; if the tumour be at all large the texture of the organ disappears; there remains only a cellular and membranous cyst. Hydatids so frequent on the exterior of the kidneys present us with examples of it. If it is in the middle of the gland that the cyst is formed, the destruction also takes place, but it is much less evident. ”

“ The head of the worm can sometimes be seen shining through as a whitish speck. The only symptoms are those of a slight irritation of the connective tissue and some difficulty in closing the lid; larger cysts dislocate the globe. The diagnosis has the rapid growth of the cystic tumour to support it; there is the possibility of its being mistaken for a foreign body (Kaldrovils718) . After division of the connective tissue capsule extraction is easily performed. It is most rare for the cysticercus to occur in the orbit. Suppuration of the cyst may have serious consequences for the eye. ”

“ The individual scolices, which appear to the naked eye as mere white points, have the form and construction of the head-segment of the mature Tænia echinococcus. After death or by violence they become easily detached, and then float free in the liquid containing them. In some cases the echinococcus cysts develop no scolices, in which condition they constitute acephalocysts. Occasionally the echinococcus embryo undergoes imperfect development, constituting the multilocular hydatid tumor, rarely found elsewhere than in the liver. ”

“ If, however, it grows upward, the area of hepatic dulness extends in that direction beyond the usual limits; the diaphragm is pushed up, the lungs forced upward to the left and compressed, and the heart also displaced upward toward the left. The extension of the tumor downward, in the direction of least resistance, is more usual. If the walls of the abdomen are sufficiently thin, the tumor large enough, and if made up of many daughter vesicles, there may be evoked by palpation the very characteristic sign known as hydatid purring. ”

“ Infection in man occurs by way of the mouth by the ingestion of cysts. A patient showing acute symptoms of dysentery is not usually infective, for he is merely harbouring the large trophozoites, which, by experiment, have been shown not to be infective to animals (kittens) when administered by the mouth. The stools of recovered patients may still contain cysts, and they may thus act as cyst-carriers or reservoirs of disease by infecting water and soil. The stools of such cyst-carriers are often solid, and so cysts of E. histolytica (tetragena) are easily overlooked. ”

“ I am in possession of hydatids from the liver of a clouded tiger (Felis macroscelis) . In England the Tænia echinococcus is excessively rare, and has not been seen in any dog which had not previously been subjected to a feeding experiment. Mr Nettleship succeeded in rearing large numbers. In Iceland, Krabbe found dogs to be infested to the extent of 28 per cent., a proportion fully explaining the prevalence of hydatid disease in that country. The remaining tapeworms of the dog belong to the genus Bothriocephalus; of these, the broad tapeworm (B. latus) is best known, because it infests man. ”

“ Infection through the embryonic form of the Tænia echinococcus, as the source of hydatid tumors, is productive of the most disastrous consequences, and has ended in the destruction of many lives both of men and domestic animals. The parasite is not directly productive of suffering, but its effects and dangers are proportioned to the size of the tumor it occasions and the character and importance to life of the organ in which the latter is situated. ”

“ Often they create pain out of all proportion to their size. Occasionally, they break and empty their contents through fistulous communications with the intestines, bladder, or the abdominal wall. But collapse of the usually thick walls of the cyst does not take place, and a cure results far less frequently than in pelvic abscesses, which empty themselves through analogous channels. The cyst ordinarily does not lessen in size; suppuration goes on with hectic fever and exhaustion, which finally carry off the patient. ”

“ In the museum at University College, I examined sixteen preparations of hydatid disease, representing almost as many distinct cases. One is a wax model. Eight of the specimens were from the liver, five from the abdomen (including those of the omentum and mesentery) , two from the lungs, and one from the heart. The model displayed ordinary hydatids of the liver bursting into the lungs. The mesenteric example is particularly fine, whilst that from the omentum is undergoing calcareous degeneration. ”

“ The _cystic lymphangioma_, _lymphatic cyst_, or _congenital cystic hygroma_ is most often met with in the neck--_hydrocele of the neck_; it is situated beneath the deep fascia, and projects either in front of or behind the sterno-mastoid muscle. It may attain a large size, the overlying skin and cyst wall may be so thin as to be translucent, and it has been known to cause serious impairment of respiration through pressing on the trachea. In the axilla also the cystic tumour may attain a considerable size (Fig. 76) ”

“ As a cyst develops it is very likely to contract adhesions to the organs with which it lies in contact. The most common adhesion is that of the omentum. Next to this is adhesion to the abdominal walls. Then will happen more rarely adhesions to the bowels, womb, bladder, pelvis, liver, and stomach. A loop of intestine will sometimes be found fastened to the front wall of the cyst, but usually the bowels lie packed behind the tumor. ”