Tumors of the Kidney.
The greater number of tumors of the kidney are malignant. Sarcoma, how ever, is much the most common form; carcinoma comes next in order; adenoma is not uncommon and is said to degen erate frequently by epithelial overgrowth into carcinoma; fibroma, lipoma, an gioma, myxoma, and tumors of the ad renal are much more rarely observed.
An incomplete development of the fi brous-tissue capsules separating the kid ney and suprarenal body is a common developmental defect. The two organs sometimes run into one another in the region of this defect. Subsequent separa tion of the two organs, each retaining portions of the other, is possible. Tumors may originate from such suprarenal or renal cysts. Tubular adenomata are rounded and smooth, reaching the size of a pea, of a bluish-red color, and soft con sistence, situated in the cortex, seen best after stripping off the capsule. The tubular adenomata probably take their origin in cysts of the renal tubules. In the trabecular cystomata the cystic nature is an important feature in this large class of kidney-tumors. Fat seems to be of constant occurrence in the epi thelial cells of the trabecular cystomata.
The trabecular cystomata also probably take their origin from the renal elements. Putting aside the tubular adenomata, there still remains two distinct types of kidney tumors.
Tumors of the first type are: 1. Com mon, subcapsular, often multiple, of all sizes. 2. Chiefly cystic; showing trabee ulm, composed of connective tissue and capillaries, later of capillaries alone. 3. Trabeculm and cyst-wall lined by single layer of epithelium, whose protoplasm contains fat.
Tumors of the second type are: 1. Pare, subcapsular, solitary, of all sizes. 2. Chiefly solid, but often show early cystic softening. 3. Cell-columns lying in capillaries, or separated from them by fine connective tissue. Richer (Centralb. f. allge. Path., June 1, '97).
In 24 cases of tumor of the capsule of the kidney, 20 were in women. In 15 the normal kidney was removed with the tumor. The tumors of the capsule are fibrolipomata, myxolipomata, and, rarely, sarcomata. The former are be nign, the second semimalignant, and the last malignant. Bork (Arch's- f. klin. Chin, vol. lxiii, No. 4, 1901).