In Fig. 53 I give an illustration from the boundary layer of a mam mary carcinoma, in which the single, already markedly atrophic gland lobules are all enveloped by the small-celled infiltration, as if by a fog. With higher powers even, we cannot recognize what happens to the gland ular epithelium under this cloud of cells; only later is the usual carcin oma structure shown. In regard to this Blebs has rightly remarked that the boundary places do not always give the clearest pictures of the gland ular structure of mammary carcinoma, but often those places, in which a part of the small-celled infiltration has already disappeared, and in which the tissue has begun to retract. The question, whether the epithelial growth or the connective tissue infiltration is the primary in the develop ment of carcinoma, can hardly be answered directly; perhaps it is one in the one case, and the other in another case.
An important objection to the essentially epithelial origin of cancer of the breast is, that it develops as a rule at a period of life in which the or gan is either about to atrophy or has already completely atrophied, so that it is scarcely very probable that at this time the glandular elements are still in a vigorous state of growth. In the section on cysts, it is seen that the epithelia of the smaller and larger excretory ducts of the gland do not fall into decay imperceptibly, as do the epithelia of the acini, but they sometimes increase actively to the period of involution, are thrown of! and by their secretory function determine the quality of the contents of the cysts. Consequently the assumption that these epithelia, under certain conditions, take on an excessive growth, would not seem to be of great importance.
We must then certainly expect that the neoplasms originating from the remaining excretory ducts lie usually near the nipple, since it is only here that finally the larger lacteal canals remain abundant But this view is shown to be erroneous, by the observation of the distribution of the small involution cysts in the atrophic glands, as these cysts frequently, indeed preponderatingly, lie in the periphery of the organ, occasionally entirely imbedded in fat, and excepting them, no remains of glandular substance are to be found in their vicinity. We may perhaps assume that individ ual groups of glandular vesicles often persist longer here than others, mid are shut out from their connection with the nipple by early obliteration of their smaller excretory ducts. There is also the supposition, which is perhaps allowable, that there are aberrant lobules in the mamma, which, by inflammatory processes or from unknown causes, are at early periods deprived of communication with the large excretory ducts, and are then especially disposed, as are all abnormally situated parts of organs, to path ological degeneration. (Volkmann, Cohnheim). Klebs has advanced
the view that the epithelial cells are also able to wander, like the so-called connective-tissue cells, and sometimes find,. in distant parts, the condi tions for their abnormal further development.
It now remains to speak of colloid carcinoma, which is very seldom found in the breast. Cases have been observed by J. Muller, Robert, Albers, Bennet, Lebert, and Doutrelepont. The case of Doutrelepont is most completely and exactly described (Akh. f. Klin. Chirurg., Bd. XII, p. 551). I too have observed such a case and possess the preparation, but unfortunately without reference to the corresponding clinical report.
How exactly my case agrees with that of Doutrelepont, Fig. 54, as to structure may be seen by comparing my illustration with his.
The epithelia play a very important part in these carcinomas; the col lection groups of epithelial cells are especially distinct because they are surrounded by a homogeneous, colloid layer, as transparent as glass, the limits of which are distinctly fixed by the connective-tissue stroma. In other respects the conditions are the same as in other cancers of the breast; the very irregularly distributed small-celled infiltration, constant only at the boundaries, and the partial fatty change of the epithelial cells, are also to be found here; retraction alone appears never to take place in these carcinomas, probably because the colloid substance is absorbed with great difficulty. The question, whence comes the colloid substance, we can only touch upon here very slightly. The regular disposition of the colloid material between the epithelial cells and the inner walls of the alveoli of the stroma permits the view, on the one hand, that the epithelial cells ex crete the colloid material; on the other hand that the connective tissue is partly metamorphosed into colloid material (myxematous tissue). That the individual epithelial cells undergo mucous metamorphosis appears to me to be without doubt from my preparations, though it is certainly not probable that, in this way, there would be such a regular disposition of the colloid substance.
In Doutrelepont's opinion, the colloid substance is a peculiar protoplasm excreted from the vessels, which at other times goes on to cell growth, but here exceptionally changes to the colloid substance. Rindfieisch has accepted this view. Klebs is more inclined to the view that the colloid substance is excreted by the epithelial cells.