In cases of multiple hydatid cysts in different parts of the body it has been asserted, upon the one hand, that a single older cyst serves as the parent cyst, germs from which become transplanted in other localities through the blood. This view receives some support from the fact that one cyst, usually seated in the liver, is commonly much larger than the others. An objection to its universal acceptance, however, as pointed out by Budd, is that it is very difficult to imagine that a germ from a larger cyst can travel through the portal vein, against the current, toward the spleen, mesentery, etc., to form a secondary cyst. On the other hand, it seems likely that an individual exposed to infection by the echinococcus would be liable to ingest many scolices at one time or on repeated occasions, and that the differences in development depend upon varying degrees of assimilative power on the part of the parasite and of the conditions of its environment.
SYMPTOMATOLOGY.—Whether echinococcus of the spleen will betray symptoms of its presence depends upon varied circumstances. Small cysts, certainly, may occasion no signs, subjective or objective. Cysts may even attain very large dimensions without exciting discomfort to their bearer, and may consequently escape detection. Pain may precede the appearance of a tumor, but will be irregular and paroxysmal, increasing in severity with the growth of the cyst. The most constant annoyance, however, is that occasioned by the size and weight of the enlargement. The patient may detect its presence accidentally, or his attention may first be directed to it by his medical attendant. He may give a history of its growth during a number of years without its having occasioned more than passing uneasiness.
The tumor may exceptionally attain a large size, nearly filling the left side of the abdominal cavity. It may encroach upon the area of the thoracic cavity. Upon examination, the tumor, when of sufficient size, will be rounded, not resembling the appearance of a simply enlarged spleen. Fluctuation will be detected, and occasionally the peculiar hydatid thrill, upon the diagnostic importance of which great stress has been placed. This, however, is a very inconstant sign, and in the majority of cases is not to be discovered. Frerichs only found it where the sac was not tense and contained other vesicles. A peritoneal friction sound may sometimes be detected by the ear placed over the region of the tumor. These cysts differ from other fluctuating tumors in being of very slow growth, remaining almost without change for years, and in exciting no constitutional reaction, unless, as is quite possible, inflammation of the sac is developed, when rigors, hectic, and other symptoms indicative of suppurative inflammation will be observed. Pressure of the tumor upon the stomach may excite anorexia, vomiting, epigastric uneasiness, and gastric catarrh. If the pressure is exerted upon the portal vein or vena cava, dropsy may result; if upon the bowel, constipation may be produced.
It is possible for the development of the cyst to be arrested through the death of the echinococcus. This may occur if it is of small size. Its walls may then become calcareous, and the mass will cease to exert any injurious influence upon the host. In other cases, as a result of inflammation, rupture will take place, and the contents of the cyst, with the characteristic formations, will escape into the peritoneal, pericardial, or pleural cavities, or into the alimentary tract, the urinary passages, or even into the vena cava; or they may be discharged through the body-wall. In any of these events a fatal termination is almost inevitable. Rupture may also occur in an unaltered cyst from any sudden or excessive violence. Death will usually speedily ensue from collapse or as a result of inflammation of the peritoneum. Finally, complete recovery will sometimes be secured through treatment.
DIAGNOSIS.—Echinococcus of the spleen presents no characteristic symptoms. When the tumor is small and escapes observation, or when the fluid nature of its contents cannot be recognized, its existence cannot be determined. In larger tumors the hydatid thrill will, when present, assist the observer, and the presence of fluctuation will of course serve to exclude all solid enlargements of the spleen from consideration. Abscess will differ in its shorter course, its rapid increase in size, and its inflammatory symptoms, the general condition contrasting with the excellent condition of health usually observed in simple hydatid tumor. The diagnosis will become greatly obscured in the event of inflammation of the cyst. Certainty can only be attained through an exploratory puncture and examination of the contents of the cysts. These will consist of a clear, non-albuminous fluid, rich in sodium chloride, and revealing the echinococcus scolices and hooks and membranous shreds when examined under the microscope. Doubt may arise where inflammatory changes have made the fluid albuminous and where the scolices and hooklets have been destroyed or do not accompany the escaped fluid.
MORBID ANATOMY.—The spleen may be almost destroyed by the hydatid cysts, which, usually single, may exist in large numbers. According to Wardell,11 "they are seldom found in the pulp, usually in the gastro-splenic epiploon or in the cysts constituted of the serous investment." The cysts consist of a thick fibrous investment and an inner parenchymatous layer, from which the little heads develop in tiny vesicles. Compound systems, one enclosed within the other, are thus formed, varying from the size of a pea to that of a marble, and even very much larger. The cysts may undergo atheromatous or calcareous degeneration. In these cases the echinococci are destroyed, and the mass becomes encapsulated in a calcareous envelope and remains quiescent. The microscope will reveal the remains of the echinococci, even after long periods. Where rupture has taken place the rent in the cyst will have allowed characteristic matters to escape into the communicating parts, where they may be detected.
11 Reynolds's System of Medicine, vol. v.
The PROGNOSIS of echinococcus of the spleen is always serious, usually most unfavorable. The best results are observed in those cases where, the cyst being small, spontaneous arrest of development has occurred. Puncture of the cyst and partial evacuation of its contents, when practicable, increase what would otherwise be almost hopeless chances of ultimate recovery in cysts of moderate and large size.
TREATMENT.—The only treatment that promises good results is the evacuation of the cyst fluid. Murchison recommends the removal of the fluid with a very small trocar, whereby the admission of air into the cavity is avoided. The withdrawal of the fluid is sufficient to destroy the life of the parasite, and in favorable cases to secure the degenerative changes of which mention has been made. The adoption of antiseptic precautions will undoubtedly increase the chances of recovery. Unfortunately, a certain number of cases will run into suppuration, when all the dangers of suppurating cavities have to be encountered, and must be treated in the usual way. Various injections into the cyst-cavity have been recommended, but they do not seem to afford better results than simple evacuation. These will probably most successfully be employed in cases where the cyst has formed inflammatory adhesions to the skin, which may be effected through the external application of caustic agents capable of exciting inflammatory changes in the deeper parts (Vienna paste, etc.). Injections may be then made through incisions carried into the cyst, without danger of exposing the peritoneal cavity. Internal medication, except for general purposes, has no efficacy in the treatment of these tumors.
Syphilis of the Spleen.