It has been shown that hemorrhagic infarction in the spleen is the result of an embolic obstruction of the splenic blood-vessels. If the embolus be simply a detached portion of an aseptic clot or fibrinous vegetation or of atheromatous degeneration, the subsequent changes will be those characteristic of the involution of hemorrhagic infarction. Under exceptional circumstances and from not understood causes inflammation and abscess may follow. These, however, are to be reckoned among the rare results of simple hemorrhagic infarction of the spleen. Altogether more frequently the embolus is derived from the ulcerative endocarditis of septic origin or from other septic centre, and consists of congeries of micro-organisms, themselves the infecting agents or the vehicles of the poison that lights up the characteristic morbid processes. A colony of these micro-organisms, lodged in and occluding splenic arteries, by the irritation of their presence and by their multiplication excite the inflammatory processes that accompany and follow the hemorrhagic infarction. Embolic splenic abscess is, then, nearly constantly a secondary result of conditions of blood-poisoning, and as such can only play a subservient part in the train of pathological events in which all parts reached by the blood-supply may be engaged. The vascular distribution in the spleen is such as to afford exceptionally favorable opportunities for the development of metastatic abscesses, and in a large proportion of spleens of those who have died from blood-poisoning they will be detected. They are rarely present without the appearance of similar changes in other organs, and there is, therefore, but little difficulty in attributing them to their true cause.
SYMPTOMATOLOGY.—Unless inflammation of the splenic capsule be excited, these abscesses give rise to no pain, neither do they (except rarely) produce discoverable splenic enlargement as distinct from the general splenic enlargement always present in septic fever. Their course is usually brief, in consequence of the usually acute course of the disease that occasions them. When, in chronic pyæmia, splenic embolic abscess may develop more slowly, exceptionally palpable fluctuating tumor becomes manifest.
Fever, with all the accompanying phenomena of blood-poisoning, is present in these cases, and commonly masks any splenic alteration that might otherwise become apparent. Embolic abscess should always be suspected in blood-poisoning, though in most cases its detection could have but little influence in determining treatment.
PATHOLOGICAL ANATOMY.—Embolic abscess may develop from a hemorrhagic infarction, in which case the necrotic central mass is surrounded by a zone of inflammation which rapidly converts the whole area into a broken-down, reddish, purulent, semi-fluid matter. If the abscess supervene without the occurrence of hemorrhagic infarction, its situation is still nearly always peripheral, the wedge-shaped embolic area pointing toward the centre. It varies in size from that of a pinhead to that of a pea and larger. It consists of a necrotic centre composed of pus-cells and detritus, a surrounding mass of exudation, and a circumscribing border of hyperæmia. Microscopic examination will usually reveal swarms of micrococci. In the progress of the abscess the whole mass becomes converted into a grumous brownish fluid. The peritoneum rarely participates in the activity of the inflammation, but may form deposits of lymph over the seats of the abscesses.
Mosler9 summarizes Ponfick's description of a peculiar splenic inflammatory process resulting from relapsing fever. It differs from ordinary embolic abscess in being limited to the splenic venous system. It may equal two-thirds of the entire spleen in bulk. It resembles in appearance embolic abscess, but the arteries remain pervious. These abscesses may heal or may enlarge and peritonitis may be excited. The possibility of their originating in a venous thrombosis is entertained by Ponfick. A peculiar inflammatory condition of the follicular tissue of the spleen has also been described by Ponfick as a result of relapsing fever.
9 Ziemssen's Cyclop., vol. iii.
DIAGNOSIS.—The diagnosis of splenic abscess presents very often great difficulties, and is frequently quite impossible. In ordinary embolic abscess a diagnosis cannot be made with certainty. The existence of pyæmia with enlargement and pain would make it probable that splenic abscess had formed. In the larger abscesses of malarial, traumatic, or unknown origin the detection of a fluctuating tumor in the region of the spleen will suggest its true cause, but examination of the contents will alone clear up the diagnosis between the real disease and hydatid tumors, nephritic and perinephritic accumulations of fluids, etc. Even where the contents of the cavity are purulent, it will often be impossible to decide upon their splenic origin unless in the event of portions of the splenic tissue escaping at the orifice of the abscess. In cases of constant and increasing pain and tenderness in the splenic region, with enlargement, associated with general failure of health, splenic abscess may be suspected, and an exploratory puncture with the aspirating-needle may not only be justifiable, but imperatively called for. In all cases it must be remembered that splenic abscess of this character is a most rare disease.
PROGNOSIS.—Splenic abscess usually terminates fatally. The life-destroying influence, however, is not exerted through the spleen itself, for this may be converted into a simple bag of semi-fluid contents, with complete destruction of all its tissue, and yet danger is to be apprehended only from the effects of suppuration or of rupture into the closed cavities or from peritonitis, etc. Of itself, embolic abscess rarely excites alarming symptoms, because, being usually of septic origin, the stress of the general condition is thrown more upon the whole body, or upon a number of its parts, of which the spleen is not the most important.
TREATMENT.—Treatment should be directed more toward prophylaxis than toward cure. In those congestions and hyperplasias that may result in abscess the remedies indicated for these conditions should be actively employed. The application of ice to the splenic region, of counter-irritants, the use of local bloodletting, the unloading of the intestinal circulation by saline purgatives, the proper employment of quinine, etc. in chronic malarial poisoning, seasonably adapted, may prevent the formation of abscess. In the event of fluctuation declaring itself, evacuation under antiseptic precautions should be practised; ordinarily, the most effective general treatment is that directed against the primary disease.
Perisplenitis.