262 Thèse de Paris, 1875.
PATHOLOGICAL ANATOMY.—In the greater number of cases, as examined at autopsies in Hearn's reports, the tumor was formed by a voluminous pocket occupying a large part or the whole of the cavity of the pleura. The walls of the envelope were formed of a transparent or slightly opaline and whitish membrane composed of numerous thin layers, containing on its interior surface the echinococci. In the interior of the cyst there was a limpid hyaline liquid with living parasites. Nothing different was noticed in cysts from those found elsewhere, except the absence of the usual adventitious membrane—a fact previously noticed by Davaine. When the cysts are very large they press upon the lung and adjoining organs just as is the case with large effusions in the pleural cavity. The heart, moreover, is pushed to one side, out of its normal position; the lung is compressed and diaphragm depressed.
SYMPTOMS.—The first appearance of cysts of the pleura causes but little disturbance of the functions of the lung. It is scarcely appreciable until it interferes with the play of the other organs. The three prominent symptoms are the pain, the dyspnoea, and the cough. The pain occupies the exact point where the tumor is situated, and radiates from that point. Once developed, it persists with tenacity throughout the duration of the disease. This persistence of the pain is indeed an important characteristic of the disease, and is a sign of value in the diagnosis between hydatids and pleuritic effusions. The dyspnoea increases progressively with the volume of the tumor. The cough is not heard as frequently as when the cysts occur in the lungs. It is dry, and does not cause hæmoptysis.
DIAGNOSIS.—Physical signs must be marked to enable us to distinguish fluid cysts of the pleura from cysts in the lung or effusions in the pleural cavity. When the hydatid tumor has attained sufficient size to cause pain and dyspnoea it generally presses outward the walls of the chest after the lung has been compressed. It does not occupy the base of the cavity, as the effusions do, and the dilatation has a globular form. Trousseau263 has given several examples in which this shape determined the diagnosis. With this arching of the chest the immobility of the chest is an important sign. Vocal fremitus is diminished or totally abolished, and percussion elicits absolute flatness. These two physical signs assist us in making the diagnosis between hydatids and pleurisy. The auscultatory phenomena, from similar physical conditions, closely resemble those of pleuritic effusions. It must be borne in mind that sometimes hydatid cysts are complicated by pleuritic inflammations, caused by their presence. The diagnosis is unquestionably complicated by difficulties that are not removed unless the cysts burst through a bronchial tube and discharge a transparent and clear fluid in which the microscope shows the presence of echinococci. Such hydatid expectoration is a pathognomonic sign of the existence of an intra-thoracic cyst. Hydatids of the liver may press the diaphragm far up into the pleural cavity without bursting through it. Trousseau maintained that without bursting they may make a passage for themselves through the distended, attenuated fibres of the muscular portion of the diaphragm, for the progress of these cysts is necessarily slow. We must not hesitate to make an exploratory aspiration to determine with certainty the nature of the fluid.
263 Loc. cit.
PROGNOSIS.—The prognosis is certainly very serious, but not so bad as when cysts of the same nature are situated in the lungs. Their spontaneous cure may be effected by bursting through a bronchus or even through the walls of the chest. The patient may, however, die from asphyxia during the discharge through the lungs. When not evacuated they may produce death by compression of the lungs.
TREATMENT.—If the disease is recognized previous to its making an opening through a bronchus, it can be treated safely and effectively by aspiration. Bird264 reports a number of cures by this operation in Australia. Trousseau advises extreme caution, even in regard to exploratory punctures, unless adhesions have taken place between the tumor and the walls of the chest, for he fears the escape of fluid into the cavity of the chest and consequent purulent pleurisy. It is well to remember that this great practitioner was not aware of the innocuousness of capillary punctures and aspiration. If the bronchus has been perforated, we must hope for spontaneous cure. If empyema be caused by the tumor pleurotomy must be used as recommended by Moutard-Martin265 and Vigla,266 and constant washing of the pleuræ must be used. This treatment gives us reasonable assurance of success.
264 Quoted by Hearn.
265 Purulent Pleurisy.
266 Loc. cit.