Carcinomatous growths occur frequently in the kidneys, and in the primary form. This is particularly the case with medullary cancer, which we find attaining a very large size, whereas areolar and hyaline cancer are extremely rare. Of these, we have observed the former only twice, in combination with medullary cancer, and the latter only as a secondary affection accompanying universal cancerous deposit.

Medullary cancer appears either in the shape of more or less numerous distinct, rounded, circumscribed masses, varying in size from that of a pea to that of a walnut and a hen's egg, of dense or soft texture (en-cephaloid), white or variously colored (melanotic); these circumstances generally attend the rapid development of universal carcinomatous deposition, and therefore indicate secondary cancer of the kidney; as a primary affection, it appears in the shape of a carcinomatous tumor, accompanied by partial infiltration and degeneration of the adjoining tissues; this tumor rapidly increases to the size of a child's or adult's head, forming rounded nodulated masses, which perforate the fibrous sheath, extend to the peritoneum, the lymphatic glands of the lumbar plexus, and involve the periosteum and ligaments of the abdominal vertebrae; the diseased tissue thus becomes fixed, after which occurrence it grows into the cavity of the renal pelves and calices, the renal veins and the vena cava, and causes their obturation.

The latter variety generally remains the focus of the carcinomatous cachexia and the sole cancer occurring in the body, on account of its extreme vegetative power; yet we not unfrequently discover in its vicinity and especially on the peritoneum, the diaphragmatic pleura of the diseased side, and in the liver, isolated cancerous deposits.

An important complication, and one that points to an analogy with tubercular disease, is that with medullary cancer in the testicle of the same side. The two commonly coexist, or the renal cancer is developed shortly after that of the testis.

We have noticed the disease not only in the middle period of life, but both in advanced age and in early youth (as early as in the fifth year). Both kidneys appear equally liable to the affection.

When the growth is effected with great violence, hyperaemia and hemorrhage not unfrequently occur in medullary carcinoma of the kidney, and when it extends into the urinary passages, we find that blood is effused into them also.