CHAPTER XXIII.

THE EPIBLASTIC AND HYPOBLASTIC GROUP OF NEOPLASMS, OR EPITHELIAL NEW GROWTHS.

THESE growths consist of

Papillomata.

Adenomata.

Carcinomata.

PAPILLOMATA.

True papilloma are new growths from the epithelium of the parts from which they spring. Most of the warty growths of the skin and papillomatous growths of the bladder come under this heading, although they contain more or less connective-tissue structures. Horny excrescences of the skin are the most typical examples of epithelial papilloma, as they consist of squamous epithelium which has undergone a horny change similar to that occurring normally in the formation of the nails,

Warty growths of the skin vary in the amount of stratified squamous epithelium covering them; in some this is very thick, and the papillae running in them are very fine processes from the cutis, much finer than normal filiform papillæ; in others they are large and the epithelium is not so thick.

In papillomatous growths in the bladder the villous projections are sometimes long and slender, with a very large blood-supply. They consist of little more than the large capillary vessel and its branches, a little fine connective tissue around it, and a covering of transitional epithelium the same as the normal epithelium of the bladder. These long processes project into the bladder, and are consequently very liable to injury and rupture of some of the vessels. Warty growths on surfaces where they are kept moist, especially by the irritation of venereal sores, are softer, more vascular, grow faster, and attain a larger size than the ordinary skin wart.

Papillomata also arise from the Fallopian tubes and ovaries; these are rare growths, and are characterized by an immense number of small papilloma on the surface which are covered by ciliated columnar

epithelium. They frequently show hyaline degeneration in different places under the epithelium, and the central portion is composed of myxomatous tissue, showing, apparently, that they do not increase at the periphery but from the centre.

ADENOMATA.

These new growths must be distinguished from hypertrophy of existing gland substance, which may arise from many causes, but is not a new growth.

True adenomata always occur in close proximity to, or in the substance of, the glands they imitate, and are probably derived from them. They are often encapsuled, especially in the mammary gland, where they are not infrequently found. In this situation they consist of a compound tubular formation, lined by columnar epithelium; in some cases they resemble the foetal condition of the gland. They sometimes reach a large size, but are perfectly innocent tumors.

In spite of their glandular formation they are functionless, and this is the principal characteristic which defines them and separates them from hyperplasias.

They often have ducts, but they do not open on the surface, neither is there any secretion found in the acini.

They are very prone, in the mammary gland, to fibrous change, and this is often of a different character from that found in the normal gland. It consists of large fasciculi of fibrous tissue similar to those found in the true skin, and having large lymph-spaces between them. There are also large lymph-spaces around the tubes being encroached on by the fibrous tissue. The number and size of the lymph-channels is a marked feature in some adenomata undergoing this degeneration.

CARCINOMATA.

Cancers are primarily divided into two groups by the character of the epithelium from which they are formed-superficial epithelium and glandular epithelium; these are again subdivided:

Superficial epithelium.

Glandular epithelium.

Squamous epithelioma.
Columnar epithelioma.
Scirrhus carcinoma.

Encephaloid carcinoma.

EPITHELIOMA.

(Squamous.) This is a new growth derived from squamous epithelium, and occurring in those parts of the body normally covered with stratified squamous epithelium, such as the epidermis, tongue, œsophagus, and os uteri. The function of the normal epithelium in these parts is that of protection, and it therefore has no secretive

Epithelioma. X 63. Shows a downward growth of stratified squamous epithelium from the epidermis, having an epithelial nest in the centre. The epithelium in the upper part has undergone a horny change.

function. This epithelium is placed on the cutis vera to protect it, and as the surface of the cutis is covered with fine papillæ, the epidermis dips down between them, forming the inter-papillary processes; without this arrangement the surface of all parts having papillæ and covered with epithelium would resemble the teeth of a saw. It is these inter-papillary processes which are first affected in epithelioma; they commence to grow downward into the cutis; soon, however, more of the epidermis does the same, and large tracts of epithelium are found growing into the cutis in a very irregular manner; as this goes on the processes of epithelium become smaller, and con

sist of only a few cells in thickness; these push their way in every direction into the cutis. These processes, as they grow, branch in every direction, sometimes at right angles, and when a section passes through a process longitudinally, with a branch growing from it at right angles, it will show in the section as a circular arrangement of cells, the so-called epithelial nests. This can easily be verified by studying

the character of the cells in the centre and those of the periphery in one of these nests; it must be remembered that a downward growth of epithelium in epithelioma has its outer cells in direct continuation. with the lower cells of the rete Malpighii of the epidermis, exactly in the same manner as in the normal development of a hair-follicle; an outgrowth from an epitheliomatous process, therefore, would have the cells arranged in the same manner, and when cut transversely, forming a nest, the peripheral cells would correspond to the rete cells and the central to those of the stratum corneum, and that they do this is selfevident by their manner of staining with logwood. The peripheral cells stain deeply and the central faintly, as with normal epidermis. These epithelioma are caused, in many cases, by some long-continued irritation, as is seen in the case of chimney-sweeps' cancer from soot, and those occurring on the arms of paraffin-workers; but

supposing this to be the case, it is difficult to understand how this irritation produces a condition entirely different from that of other long-continued irritation.

Intermittent irritation, such as the pressure of a tight boot, causes a corn; other forms of intermittent pressure cause thickening of the epidermis in different parts. But this thickening is all caused by an outward growth of the epidermis; its relations to the cutis are not altered. In the case of an epithelioma the reverse is the case; the increased growth is downward, and this is exactly the same process by which all the appendages of the skin are formed in development. There is, in fact, a return to the foetal condition. Whatever the cause may be, the epidermis returns to the condition it was in before development was completed. The theory that the physiological resistance of tissues is removed and the epithelium allowed to grow, is too purely theoretical to be considered. Some epithelioma vary in their structure, having large, horny masses in the processes; this is caused by an increased corneous change taking place in these particular cases; these horny masses show a yellow color in logwood-stained sections in the same manner as normal horny substance, as in the papillæ of the cat's tongue.

There are some rare forms of new growth in the skin which ought to come under the heading of epithelioma, where masses of epithelial cells grow into and distend the lymphatic spaces, but do not bore their way into the cutis in the manner before described; they have been called sarcoma, but the cells are clearly of epithelial type, although it is sometimes uncertain where they started from.

RODENT ULCER. ·

Nearly allied to the last form, it is not clear whether rodent ulcer is a kind of local epithelioma of slow growth or whether it is developed from other structures than the epidermis, and in this way gets its peculiar mode of growth. It may possibly be derived from sweat or sebaceous glands; but sebaceous glands at any rate are capable of forming true epithelioma, as shown in specimens in the author's possession. The only material difference the writer has been able to make out is, in some cases, in the formation of nests. These are entirely formed of cells like the cells of the rete Malpighii of the normal skin; they are regularly arranged, and all stained alike; this occurred in only two cases, however, out of a large number examined.