TUMORS OF THE SPLEEN.
Secondary. Delay of blood favors. Sarcoma: horse, cattle, dog. Carcinoma: horse, dog. Melanoma: common and large in gray and white horses, rupture, external melanosis. Angioma: horse, ox. Lymphadenoma: horse, ox, external adenoma.
The different tumors of the spleen are usually secondary. The intimate structure of the organ, the peculiarity of the circulation through the pulp cavities, and the delay of the blood in the pulp spaces, predispose it in a very especial manner to the growth of neoplasms, the germs or bioplasts of which are carried in the blood.
Sarcoma. In the horse sarcomata have been found in the spleen secondary to similar tumors in the other parts of the abdominal and thoracic cavities. They may attain to any size, from a pea to the closed fist and, in exceptional cases, of a mass which practically fills and distends the abdominal cavity.
In the cow an encephaloid sarcoma in the spleen, weighed nine pounds and was associated with similar formations in the lymph glands generally of the abdomen and chest.
In the dog also sarcomata are common in the spleen.
Carcinoma. These are found in the horse in connection with similar primary tumors, as in the case of the sarcomata. They are at times extremely vascular and soft, and at other times they are hard and fibrous (scirrhus).
In the dog secondary cancer of the spleen is comparatively common.
Melanoma. Black pigment tumors are especially common in gray and white horses. Their common seat is on the black, hairless portions of the skin (anus, vulva, perineum, tail, sheath, mamma, eyelids, lips, etc.), and secondarily in the lymph glands and spleen. In the latter they may grow to an extreme size, Wehenkel having mentioned one specimen of 60 pounds. Its surface is marked by uneven, rounded black swellings, the entire organ, indeed, seeming to be a conglomerate of these masses. The intimate structure is that of a sarcoma, so abundantly charged with black pigment granules that these appear to make up the greater part of the mass.
Rupture of these neoplasms with the escape into the abdomen of blood highly charged with the melanic matter is not uncommon.
The symptoms of the splenic deposits are not usually recognizable, but indications of chronic abdominal disease in connection with external melanotic formations may well lead to a reasonable suspicion.
Angioma. In a horse’s spleen weighing 30 lbs., there were numerous soft nodules of a deep cherry color. These were cavernous masses with connective tissue walls and the meshes filled with blood.
Similar vascular cavernous tumors have been found in the cow.
Lymphadenoma has been found in the spleen of horses and cattle in connection with the same disease of the lymph glands.
Like the other splenic tumors this is obscure and usually only found after death. The existence of adenoid swellings elsewhere conjoined with excess of white globules and indications of abdominal pain would be suggestive of splenic disease.