Section V. the Spleen.

=Congenital Anomalies.= In acephalous monsters the spleen is generally absent. Occasionally in subjects otherwise well developed, it is wanting, together with the stomach or the fundus of the stomach.

Congenital displacements have been met with.

Supernumerary spleens, varying in number and small in size, are frequently met with.

=Hypertrophy and Atrophy.= Probably no organ of the body is as liable to such great variations in size as the spleen. The normal spleen in the adult, in whom it attains its greatest size, is usually about five inches in length, three to four in breadth, and an inch or an inch and a-half in thickness, and weighs about seven ounces. Its size is increased during and after digestion, and varies considerably according to the state of nutrition of the body. In typhus the spleen is enlarged, the parenchyma exceedingly soft, its color a dirty red, of different shades. In leukæmia it is also found greatly enlarged, but of a denser consistence. Rokitansky states that the spleen not unfrequently measures sixteen inches in length, seven in breadth, and four inches in thickness, and its weight may amount to twelve or fourteen pounds, or, according to others, to twenty or even forty pounds. (Huschke.)

Most of the hypertrophies of the spleen are accompanied not only by an engorgement of the very numerous vessels, but by an alteration and increase of the red, pulpy parenchyma.

Atrophy may reduce the spleen to the size of a hen’s egg or a walnut. It takes place normally in advanced age.

=Displacements.= Some of these are congenital: thus it has been found by the side of the bladder; in the right side of the thorax; in the left thoracic cavity when the diaphragm was absent; and external to the abdomen in large umbilical herniæ, or where the abdominal walls had not closed.

Other displacements are the result of disease. The enlargement or distension of adjacent parts, or increase in its own size with laxity of its ligaments, causes it frequently to be displaced, and even to descend into the pelvis.

=Rupture= occasionally happens as the result of injuries. Spontaneous rupture in intense congestions during typhus, cholera, and the cold stage of ague, has occurred. This always proves fatal.

=Inflammation.= Primary inflammation of the spleen is comparatively rare. Unless it ends in resolution, it gives rise to the formation of laudable pus or fibrin, which may either be contained in a circumscribed abscess, and thence become obsolete, or the cavity may enlarge until the pus penetrates into the left thoracic cavity, the stomach, the transverse colon, or the peritoneum.

Secondary splenitis is regarded as identical with pyæmic deposits. The deposits are well defined, always at the periphery, cuneiform in shape, the apex directed inwards. Their color is darker than the surrounding tissue, and their consistence firmer. They are either converted into a cellulo-fibrous callus, which contracts and causes a cicatrix in the surface; or “into a puriform, creamy mass; or into a sanious greenish, greenish-brown, or chocolate-colored pulp.” There are also fibrinous deposits frequently found in the parenchyma of the spleen, classed by some among the phenomena of secondary splenitis, but regarded by others as a simple exudation of fibrin, from an excess of this in the blood. These deposits appear as a circumscribed yellowish mass, with a margin of darker or lighter red congestion of increased consistence, easily recognized when handling the part, “and showing under the microscope a confused mass of granular with more or less oily matter infiltrated among the remains of the parenchyma. They very commonly undergo fatty degeneration.”

=Chronic Thickening of the Capsule= of the spleen is of frequent occurrence. It seems to take place at the expense of the parenchyma of the organ, and may proceed to a very great extent. It is usually pretty uniform. Ossification of the thickened fibroid layers is rare, except in old persons.

=Amyloid Degeneration of the Spleen.= The disease may be limited to the Malpighian corpuscles, constituting the so-called “sago spleen,” or it may extend and implicate the pulpy parenchyma between the corpuscles.

The sago spleen is more or less enlarged; its weight and density are increased. On section, the surface appears smooth, dry, and studded with glistening sago-like bodies, varying in size. An iodine solution gives them a reddish-brown color.

In the more advanced stage, where the pulp is infiltrated with the new material, the organ generally is much larger than in the sago spleen. It is hard and firm; the capsule tense and transparent. The cut surface is dry, homogeneous, translucent, bloodless, of a uniform dark, reddish-brown color. The organ can be cut like wax. The corpuscles are obscured by the surrounding pulp.

Morbid Growths.

Tuberculous matter is commonly deposited in the spleen, only in connection with general tuberculosis. It appears in the form of gray granulations, miliary crude tubercles, or yellowish cheesy masses of various sizes.

Cysts have been observed in the capsule of the spleen. They are small, of conical shape, and lightish red color, containing numerous granular cells, floating in a transparent liquid.

Hydatid cysts may be found in the spleen alone, or at the same time with one in the liver.

Cancer is rare. The encephaloid is the only form met with, and generally only with similar disease in the liver, stomach or omentum.