TUMORS OF THE KIDNEY.
The subjoined list of tumors, given in tabular form, shows at a glance the various kinds of enlargement of the organ, or of the struc tures immediately connected with it, which clinically constitute a renal tumor. To render the table complete we include, on the one hand, some inflammatory and other swellings, which though not neo plasms, are at the bedside regarded as tumors; and, on the other, some rare or minute growths which are definite pathological new formations, though of insignificant clinical importance.
The tumors are arranged primarily in two groups. The first in cludes those of congenital, and the second those of post-congenital, origin. This arrangement is warranted by both clinical and patho logical experience. Clinically we recognize the rarity of renal tumors during late childhood and early adult life, while they are compara tively not uncommon before five or after thirty. Pathologically it is found that the early growths have a minute structure unlike the later growths, and one which indicates that they, like the congenital cystic disease and hydronephrosis, are referable to abnormalities of devel opment. It is in the congenital sarcomata only (though these rarely show themselves late in life) that a complex minute structure is met with, including such various tissues as striped muscle, fat, and other connective and glandular tissues, and pointing to their origin from structures derived from the Wolffian body or intermediate cell-mass, and included in the substance of the true kidney. To congenital cystic disease a similar origin has been ascribed; the cysts are said to be derived from the remains of the Wolffian body (Shattuck). Hydronephrosis the result of congenital abnormalities is much more frequent than the cystic disease, and has a considerably greater clini cal importance. Dermoid cysts are mentioned, but it is doubtful if any examples have actually been met with in the human subject. Cavernous tumors are small, and give rise to no symptoms. They probably correspond in origin and growth to similar tumors in the skin.
The post-congenital tumors are subdivided into three groups ac cording to their anatomical position. Of those which are extra-renal, abscess has already been dealt with. Extra-renal serous cysts are rare, and their etiology is not very well understood. Large myxo lipomatous tumors occasionally grow from the pefi-renal fat, and are properly included among the renal tumors, as this fat has a de finite anatomical relation to the kidney. Tumors of the adrenal are often so intimately connected with the kidney that it is impossible to differentiate them clinically, as may generally be done when the enlargement is in the spleen, liver, glands, or bowel. And when the
tumor is malignant it infiltrates the kidney at such an early stage that it may be impossible, even post mortem, to decide in which organ it originated.
The pelvic group include hydro- and pyo-nephrosis, already treated of, vinous tumor or papilloma, and carcinoma. The pelvic mucous membrane has the same structure as the lining membrane of the bladder, and it is, therefore, as we should expect, subject to the same varieties of new growth. Vinous tumor is uncommon, but may attain a considerable size. It is exactly like that which grows in the blad der. Squamous-celled epithelioma is the usual kind of carcinoma met with in this locality; it is more frequent than the preceding. Colloid carcinoma is the only other variety. It is very rare.
The glandular and capsular group is composed of many species, of which tubercular disease, sarcoma, and carcinoma are by far the most important. Hydatid cysts may occupy any position in regard to the organ. They are much less frequent here than in the liver, but can hardly be regarded as curiosities. Cystic disease is rare. It may give rise to great enlargement of one or both organs with symp toms of Bright's disease. The tubercular affections have been de scribed. Lymphadenomatous growth in the kidney sometimes forms a part of Hodgkin's disease. Syphilitic gummata are distinctly rare in the kidney. When seen they are found accidentally post mor tem. Unlike similar deposits in the liver they do not appear to attain clinically recognizable proportions. Lipoma in the kidney substance is rare and small. The fibromata described are very small, but are frequently observed. Neither of the two latter have any clinical significance. Of the sarcomata the small round-celled variety is that which is almost constantly met with; but some very interest ing specimens of a vascular or hemorrhagic tumor of the kidney have been recorded, and it is not decided whether they should be called angeio-sarcoma or hemorrhagic carcinoma. Adenoma occurs as small, more or less encapsuled tumors, having a tubular or cystic structure. The typical carcinoma is also tubular and sometimes cystic; but there is at present no satisfactory account of the patho logical varieties which may occur in this region. Secondary sarcoma and carcinoma are less frequent in the kidney than in the lungs or liver, and the growths rarely attain sufficient size to seriously impede the functions of the organ, except in the case of the direct infiltration of a neighboring tumor.