PULMONARY HYDATIDS.

BY EDWARD T. BRUEN, M. D.

DEFINITION. A disease in the lungs consequent upon the entrance into the human system of the eggs of a small tape-worm, whose usual habitat is the upper half of the small intestine of the dog.

SYNONYMS. Tænia echinococcus; Acephalocyst. Fr. Kystes hydatiques du poumon; Ger. Lungenechinococcus.

HISTORY.-Unmistakable references to this disease are found in the writings of Hippocrates, Aretæus, Galen, and other early writers. For a long time, however, the animal character of the hydatid cyst was not recognized, but confounded with slowly-developed local dropsies of various orders and with lymphatic dilatations. Their animal nature was suspected by Hartman in 1685, but their origin was not separated from the cysticercus. In 1766, Pallas clearly distinguished the two species, and this author was followed in a more positive way by Groeze in 1782. Laennec in 1804 carefully studied the hydatid cyst as found in the sheep, recognizing even the mode of reproduction, but he erroneously described the same parasite, when existing in man, as a distinct animal, which he termed acephalocyst. Since 1821, Bremsen, Davaine, Küchenmeister, and others have definitely settled the true mode of the entrance of the Tania echinococcus into the human system, and the subsequent development of the hydatid cysts. The development of the parasite resembles that of the cysticercus. Like the latter, the larvæ infest the bowels of certain animals, and take their further development in a different animal or species, forming vesicles which are distributed in the parenchyma of the different organs, and in this way more or less seriously compromising the functional life of the part in which they occur.

ETIOLOGY. (See article on INTESTINAL WORMS, by Leidy.)-Hydatids have been found in the human subject in all countries, but especially in France, Germany, and in the north of Europe. They are rarely found in North America, and the fact that the majority of cases seen here have occurred in foreigners favors the probability of the hydatid disease having been imported. But there are two countries where it may be said to be endemic-Iceland and Australia. Finsen found 1 out of every 43 inhab itants affected with this disease in the district of Ofjord in Iceland. Hydatids are communicated to the human race through the system of the dog, and in Iceland the proportion of these animals to the population is probably more than 1 to 3, a recent census recording 20,000 dogs to 70,000 inhabitants. Hydatids usually enter the system through the digestive and respiratory organs. The Icelanders are excessively uncleanly and careless of the laws of ventilation. In the winter season both men and women are confined to the house in company with their dogs, and in consequence the air is impregnated, and oftentimes the drinking-water contaminated, through their dejecta, which contain thousands of the eggs of the echinococci. The largest

number of cases occur in the agricultural districts, since the dogs are more required there than on the sea-coast.

In Australia large numbers of dogs are maintained to guard the sheep. The droppings of these animals, dried by the hot winds, are inhaled as dust. It is curious to note that in Australia, where the high winds prevail, the proportion of pulmonary hydatids is very large, while in Iceland, where the drinking-water is the principal medium of communication, the lungs are less often affected than other viscera. Finsen's records in the latter country show 255 cases; of these, 176 occurred in the liver, and only 7 in the lungs. In both Iceland and Australia women are more subject to echinococci than men. This is possibly accounted for by the facts that the women take care of the dogs and wash the vessels from which they eat, and are also less protected by hair about the mouth and nose than men.

The disease occurs most often between the ages of twenty and thirty years, but it has been found in children of four years of age. Before ten and after sixty the proportion of cases in both sexes is equal. The malady is not hereditary, but uniformity of environment accounts for the propagation in communities. Pulmonary hydatids occur as primary formations in the lungs, but may be secondary to similar growths elsewhere, especially in the liver. There is, however, scarcely a tissue in the body in which hydatids have not been found.

MORBID ANATOMY.-Hydatid cysts consist of sacs of various sizes, from that of a pea to an orange or even an adult head. They are usually globular in shape, and attached by a vascular membrane to the organ in which they are situated. The walls of the cysts are composed of a few laminae of indeterminate membrane of varying thicknesses, commonly depending on the age of the cyst. In young cysts they occur in direct contact with the lung, but as they grow larger a thicker investment is formed, and large old cysts which have generally undergone spontaneous rupture often have a dense leathery sac. Walsh asserts that the parent cyst lies in direct contact with the lungtissue, and, unlike that of the liver, is rarely surrounded with a thick shell or cyst-wall of pseudo-areolar tissue. The interior of the pouch is smooth and of the aspect of serous membrane without epithelial covering. The parent cyst contains daughter cysts which are single or multiple, and a liquid the proportion of which is variable. This liquid is nearly limpid, and non-coagulable by heat or acids; it deposits by evaporation crystals of chloride of sodium.

Commonly, only one hydatid tumor is found in the human lungs, although in animals multiplicity of cysts is the rule. They are usually located in the base of the lungs, and are thought to be more common on the right side, but they may occupy any portion of one or both lungs. They have been found in the pleura, the bronchi, the pericardium, and the thyroid gland. In the pleural cavity they may be attached to both the costal and the visceral pleura; in the latter case they may form an outgrowth from the lung into the pleural cavity. Authorities differ as to the condition of the neighboring lung-tissue, some stating that the cysts are rarely surrounded by healthy lung-substance, while others assert the contrary. Since the growth of the cysts is often very slow, the accommodating power of the lung is remarkable when no constitutional mischief exists. In some instances the rapid enlargement of a cyst has been accompanied by certain forms of pneumonia, secondary inflammatory lesions, congestion of the neighboring tissue, splenification, or even gangrene.

Hydatids situated either in the lung or pleura may rupture into the bronchial tubes, and thence be discharged by cough and expectoration, or they may open externally like a pleural empyema, or even rupture through the diaphragm into the intestines or peritoneum. None of the above accidents are necessarily fatal, not even the latter, unless the fluid be puriform. Em

pyema with pneumothorax usually follows rupture into the pleura. Finsen observes that a general urticaria may follow the rupture of a cyst into a serous cavity. In old cases, after rupture of cysts, pulmonary changes may almost always be found. The ruptured cyst may become a suppurating cavity, suggesting the possible development of phthisis. In some cases hydatid formations have been described with coexisting catarrhal or tubercular disease, or these processes may occur as a complication without rupture of the cyst.

SYMPTOMS.-The symptoms of hydatid cysts are obscure, and the physical signs difficult to analyze when the cysts are small. They are more suggestive when the cyst becomes large enough to contain a pint or more of fluid. The outline of the cyst is usually globular, and is imbedded in healthy or nearly healthy lung-tissue. According to Bird, the physical signs correspond with those familiar to us in pleural effusions: absolute dulness or flatness on percussion, with absence of respiratory murmur over a space of the chest-wall not smaller than the palm of the hand; vocal fremitus and resonance are also abolished. The expansion of the chest is more or less deficient upon the affected side, but seldom with any change on mensuration.

The area of the above physical signs usually presents a rounded outline, limited by a line of demarcation so exact that it can be mapped out with pen and ink, but is unaltered by position. Their location is generally in the lateral or infra-clavicular regions; beyond the boundary-line percussion is vesiculo-tympanitic resonant or normal, and the respiratory sounds begin at the very margin of the pen-and-ink line, and, though probably harsh and puerile in character, are indicative of healthy lung-tissue.

Pulmonary hydatids can seldom be examined by palpation, but all authors allude to a frémissement or peripheral fluctuation which may sometimes, but not invariably, be detected by palpation over the intercostal spaces. Davaine directs palpation as one would palpate an abdominal cyst. The sensation of fluctuation is as though the fluid were gelatinous; when the quantity of liquid is excessive this movement is not perceptible. It is most recognizable when there is but a single hydatid in the parent cyst (Jobert). The frémissement cannot be felt when the sac has undergone atheromatous degeneration, because there is then no liquid, and the cysts are withered, agglutinated to one another, and the tumor is inelastic and hard. By auscultating the tumor while practising percussion one may hear more or less positive vibrations resembling those produced by a bass string (Briançon).

The general symptoms of pulmonary hydatids are of mechanical origin: pain, dyspnoea, cough, with duskiness of the surface, all of which are more or less marked according to the size and location of the tumor and its rapidity of growth. A phthisical appearance is possible, with deterioration of the blood-crasis and progressive loss of flesh. Marked clubbing of the fingerends 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. There is much diversity of opinion as to the frequency of hæmoptysis, many authors looking on it as a rare symptom. According to Bird, there is seldom or never profuse hæmoptysis, though several ounces have been expectorated at a time in an aggravated case where tapping had been long delayed. The cause of hæmoptysis is usually pressure of the growing cyst upon the pulmonary veins, leading to extravasations of blood.

If dyspnoea with deficient aëration of the blood, wasting, clubbed fingers, and expectoration persist after the expulsion or death of the hydatid, the probability is in favor of some associated pulmonary inflammation. When

a hydatid cyst ruptures into the bronchial passages, there is serious likelihood that the patient may choke or suffocative dyspnoea supervene. The quantity of entozoal substance voided at any one time varies from a few microscopical fragments up to a pint or more of unbroken acephalocysts. The expectoration of acephalocysts may continue several months. Serious general pulinonary symptoms precede and follow this accident. When rupture has taken place into a bronchial tube, there are the usual physical signs of a pulmonary abscess or large vomica. The sac usually suppurates, and there is a constant expectoration of blood, pus, and half-putrid acephalocysts of excessive fetor, and often portions of gangrenous lung-tissue. With these symptoms the temperature is sometimes of a low, remittent type, with hectic and sweats. The symptoms resemble those of empyema or advanced phthisis, and may continue for months, until the patient, in most cases, sinks from exhaustion, unless relieved by the evacuation of the sac and its contents. When hydatids develop in the pleural cavity the signs are identical with a localized pleural effusion.

Nothing has been said to differentiate pulmonary-hydatid expectoration from cases where an hepatic hydatid cyst has burst into the lungs, and the diagnosis may be very difficult. The physical signs of enlarged liver are present, also the antecedent symptoms of disordered hepatic action, especially intestinal indigestion and the staining of the sputa with bile. If the cyst has undergone suppuration, the symptoms may be allied to those of hepatic abscess.

The nucleation of testimony favors the view that a latent or slow growth is by far the most common history of hydatids. Their duration is very variable: patients may harbor them for a long time unconsciously, even over a period of sixty years. This is corroborated by Finsen, who reports cases in which the disease lasted sixteen, eighteen, and fifty-two years, proving this by stating that these individuals had left the country where the disease was endemic, and were residing during these periods where the malady was

rare.

TERMINATIONS.-30 or 40 per cent. of cases terminate in recovery if the cysts spontaneously burst, death being caused in others by suppuration and exhaustion. There is, in addition, the risk of sudden death from the rupture of a large cyst in the lung, and consequent filling up of the air-passages by its contents. The cysts may sometimes undergo atheromatous changes in which the hydatids resemble crushed grape-seeds. Microscopically, one finds a puriform fluid, plates of cholesterin, crystals of hæmatoidin, hooklets of echinococci, and débris of membranes. Again, the cysts may resemble a caseous or cretaceous tubercle without special characteristics. This may be looked on as a species of spontaneous cure. The growth of hydatid cysts may bring about by pressure such a state of chronic pulmonary engorgement that it affords a predisposing condition favoring the development of tubercular phthisis.

DIAGNOSIS.-The differential diagnosis is necessarily difficult. The nationality of the subject and the presence of a predisposing environment should always be remembered. If the disease progresses rapidly without interference, the diagnosis may be complicated by the development of patches of bronchitis or pneumonia with rusty sputa. The bronchitis is, however, local, which, taken with the physical signs of a cyst, may be suggestive. The only absolute evidence of the existence of hydatids in the lungs, whether primary or secondary, is the appearance in the sputa of the characteristic cysts or portions of them, such as fragments of the hooklets of the echinococci. This, unfortunately, occurs as a late accident in their history. If the boundaries of the cyst can be recognized, it is justifiable to resort to paracentesis, and thereby withdraw some fluid for examination. The physical signs of local serous effusion, globular in shape, not evenly dis

tributed around the circumference of the chest, is one of the best differential evidences between hydatids and pleural effusion. Moreover, there is no fever in hydatids unless after rupture, or with extensive phthisical complication, while there is a history of fever in some stage of most cases of pleurisy. Hydrothorax is differentiated through its being bilateral and by its etiology. From local encysted pleurisy the only resort is exploratory puncture and the question of the probabilities in each case. 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.

PROGNOSIS. According to Reynaud, this depends on-1, whether the hydatid is single or multiple; 2, whether the pressure is exercised on bloodvessels or bronchi; 3, if hydatids are discovered elsewhere; 4, size of cyst; 5, alterations in the walls of cysts; 6, whether complicated with any other disease or independent.

If there is a tendency to pulmonary phthisis, inherited or acquired, or if this disease exists as a complication, it forms an unfavorable element in the prognosis. Persons once affected with hydatids are more susceptible to a second invasion of the parasite. The practicability of treatment by tapping is also an element in the prognosis.

TREATMENT.-Naturally, the preventive treatment rationally deduced from the now distinctly-understood causes should be practised. The water-supply should be protected from sources of contamination, and in addition the inhabitants of countries where the disease is prevalent should, as far as practicable, use boiled or stone-filtered water and refrain from eating water-cresses or plants of like character wherever these are liable to be contaminated.

Many drugs have been administered, among them the bromide and iodide of potassium; solutions of salt are also said to be deleterious to the life of the echinococcus; Laennec even prescribed salt baths. Tincture of kamela has been recommended by Hjaltelin, a physician in the employ of the Danish government in Iceland. He administered it in doses of thirty drops daily to adults, continuing its use during a month or more. It has a distinctly irritating and destructive effect on the acephalocyst (Bird). Turpentine, from its well-known anthelmintic powers and ready diffusibility, has naturally suggested itself as a remedy, and according to some has proved of great service in many instances, while in others it has signally failed.

Paracentesis is generally regarded as the most efficacious treatment, and may be carried out upon the principles usually applied in the treatment of hydrothorax. Bird recommends that the trocar should be not less than six inches long and of the smallest diameter that is made, always providing that it is strong enough to bear the strain of a firm pressure. Cysts can be tapped in this manner even when they are separated from the chest-wall by quite a deep layer of lung-substance. This treatment should be practised at the earliest possible period in the life of the cyst. Speaking of the aspirator, he says that cases always do so well if tapped early enough with the simple trocar and canula that aspiration is not required. The gradual expansion of the lung as the cyst is emptied is sufficient to expel all the fluid, especially if aided by the effects of coughing. In exceptional cases of old standing, where there is a thick adventitious external wall to the cyst, which is generally closely adherent to the ribs, or again in cysts of the pleura, a free antecedent incision of the external tissues is sometimes required. It has been suggested by different authors that tincture of iodine should be injected after