We would probably have advanced but little, had we confined our studies of the development of sarcoma to cancer of the breast; neverthe less, the studies of Thiersch, on cancer of the skin, illumined in a spirited manner by reference to normal histogenetic processes, soon advanced the matter further and brought it, with the exception of many doubtful points, to a certain conclusion. In this connection I may refer to the later works on pathological histology and general surgery, and would only call atten tion to the fact that it has been made obvious, especially by Waldeyer's work, that in cancer of the breast the cancer cells lying in the alveoli, which ho calls " cancer bodies," spring from the epithelial glandular cells. As these epithelial forms in carcinoma never spread over the em bryonal parts of the gland, and also deviate in their formations from the normal types of the mamma, he rightly calls carcinoma an " atypical ep ithelial tumor." As already said, we must give up trying to directly observe the deriv ation of cancer cells from the true epithelia; so also the first stages of division are concealed by the complicated tissue in the examination. It appears that, through a few generations, the small epithelial cells of the acini or gland ducts scarcely ever (in many carcinomas perhaps never) grow out over the normal mass, but later, when they are freed from pres sure by a kind of softening process of the surrounding connective tissue, they reach the size in which we find them in the formed parts of the car cinoma. Nevertheless, we sometimes meet with carcinomas which allow us to see with especial clearness the process on their boundaries; there are pictures especially, which we obtain by very low powers, which give us accurately, as it seems to me, undoubted conclusions in this direction.
In Figure 46 we see, in a mamma, already in a state of involution, the gradual changes of the lobules in succession at a, b, c, d. The ends of the gland elements, which have again already become bulbar by the partial atrophy of the acini, are filled with cells and thus become larger and larger, though still clearly preserving the glandular forms for a time; and finally they grow over the boundaries of the connective tissue between the gland lobules; in this way there occurs a confluence of foci, as at d. With a higher power this acinous structure becomes xery distinct in cer tain selected places, until it finally assumes the type of the alveolar tissue, (Fig. 45).
Most of the soft, larger noduled carcinomas have this kind of develop ment and this structure.
Another form I have also designated as "tubular" carcinoma of the breast. It is characterized by the outgrowths of the epithelial mass in the form of elongated, ramifying cylinders or filled tubes (tubuli), which, soon growing over the boundaries of the original acini, cause a confluence of these as in the previous form.
The order of development in the last illustration (Fig. 4l) is a, b, c, d, e. By rapid progressive growth, what is seen in Figure 45 is finally attained. It is clear that only by the careful adjustment of sections can the elongated forms, the tubuli, be brought into view, and that these, if cut across, may give the impression of acini. But besides this, combina
tions of the acinous and tubular forms are quite frequent, and the separ ation not always sharply defined. But there are still other marks, which serve to indicate this more tubular form. Here the cancer cells are usu ally not so large as in the soft acinous forms. The character of the infil tration is here more important than the formation of nodes and nodules. But especially important in these carcinomas, which principally correspond to the carcinoma simplex, the infiltrated carcinoma of the English, is an appearance which is infrequent in the first forms, namely, a peculiar kind of atrophy and a rfial cicatricial contraction.
The small-celled infiltration of the connective tissue, which is found here and there in carcinoma, has exactly the character of a chronic in flammatory infiltration. The more carefully I have studied the degener ated tissue, the more have I been convinced that a collection of the small round cells in groups is of the greatest infrequency. The illustrations which formerly I thus explained allow also another interpretation, that these groups of cells are cross and oblique sections of thinner tubules, proliferating, but still slightly enlarged outgrowths (daughter-cells) of the epithelial cells, which push themselves forward, growing into the narrow connective-tissue spaces.
As regards the fate of the infiltrated fibrous tissue, it gradually becomes, by cellular infiltration, softer and more pliable, so that the epithelial cells can now expand more readily. With this small-celled infiltration is con stantly connected an increase of the capillary and venous vessels, which likewise contributes to make the tissue softer, and, at the same time, brings to it more fluid nutriment; there is thus a kind of chronic hyperm mia and a chronic, partial indurated oedema. In this way the similarity to a chronic inflammatory process amounts to identity. We will best notice this, when the degenerative process attacks the skin; here the skin behaves exactly as it does before the outbreak of a chronic eczema on the leg, or before the beginning of ulceration in varicosities. The nature of the ulceration over these infiltrated cancers of the breast is exactly the same as on the leg under the circumstances mentioned. On the red, stiff skin, vesicles, bulh'e, scabs, clefts and fissures are formed, under which at first superficial, and then constantly deepening, ulcers develop by slow breaking down of the tissue.
In the interior there is also such a partial breaking down of the infil trated tissue (both of the epithelial and connective tissue elements). The results of this are manifold. If the cell proliferation is very rapid and luxuriant, there is consequently great compression of the nerves and ves sels contained therein; the latter are gradually distended by the partial compression, and if the pressure increases, stasis and thrombosis occur. In this way the flow of the fluid nutriment to the vascular territory ceases, and the cancer cells first take on fatty degeneration and then break down. This breaking down finally extends to the thrombotic vessels.