A system of practical medicine. By American authors. Vol. 1

by Unknown

Local peculiarities of tissue, whether congenital or acquired, are thus regarded as representing the beginnings of the growth. With the multiplication of the cells their transformation may take place or a change in their grouping may arise. The essential condition in the production of the morbid growth is that the formation of the cells should take place at an abnormal time or place and should progress in a normal or abnormal manner.

The growth takes place with greater or less rapidity in one or another direction according to the nature of the tumor and its seat. The more closely the tumor resembles the normal structures of the body, the slower is its growth; the more it differs in composition, the more rapid is its progress. This difference may arise from a predominance of cells over intercellular substance, as in the case of the sarcoma, or it may result from an atypical combination of tissues, as seen in the development of epithelium and connective tissue in cancer.

The seat of the tumor is of importance mainly on account of the vascular supply of a part and the more spongy or yielding nature of certain regions. That the more abundant the nutrition of certain regions of the body, the more favorable the opportunities for growth, may be admitted without question. The spongy nature of tissues implies a predominance of cavities over solid constituents. These cavities are lined by surfaces which represent, on the one hand, the walls of lymph-spaces, on the other the free surfaces of the body exposed to the air, as the mucous or cutaneous surfaces and the pulmonary surface. The rapidity of growth in the direction of the least resistance is amply shown in the projection of tumors above the surface of serous membranes and the frequent presence of fungoid excrescences in various parts of the body.

The growth of tumors extends in all directions, but a distinction has long been drawn between the concentric or interstitial manner of growth and the excentric or infiltrating form. This distinction is based upon the presence of a sharply defined limitation of pathological and normal tissues or upon the absence of such a limitation. Such a distinction is merely of relative importance, as certain tumors may grow in both ways. This is best observed in those bulging superficial tumors whose base is irregularly extended into the continuous healthy tissues.

The concentric variety of growth includes those tumors which have commonly been described as encapsulated, and which are capable of ready enucleation from their surroundings in virtue of a thin layer of loose connective tissue lying between the tumor and the contiguous tissue. Such a capsule represents the matrix, the pia mater, in which lie the blood-vessels going to and coming from the tumor, and is often nothing else than the distended and hyperplastic fibrous tissue remaining after the absorption of the muscular fibres or gland-cells from the tissues surrounding the morbid growth.

The excentric, peripheral, or infiltrating extension of the tumor takes place when the surrounding parts are invaded by the active elements of which the tumor is composed. The amoeboid property of the cells of certain tumors is well known, and the possibility is admissible that the indifferent cells of the body, so often accumulated at the periphery of the growth, become impregnated with a formative function by the constituents of the tumor. Such amoeboid and wandering cells represent a means through which the growth of the tumor may become extended in its vicinity as well as in more remote parts of the body.

The extension in the vicinity may be continuous or the reverse, the latter through the formation of secondary nodules, which may eventually become fused with the primary mass. The continuous growth takes place, as has been more particularly shown by Köster, along the lymph-channels surrounding the tumor, which may become filled, distended, and eventually obliterated by projections from the neoplasm. Both methods of peripheral growth, by secondary nodules and continuous extension, represent an infection of the surrounding tissues, especially if it be admitted that the cells through which the increase is accomplished are direct descendants of the pre-existing cells of the part. Not only does the extension take place through the lymphatic vessels about the tumor, but blood-spaces as well as lymph-spaces may be invaded. Thrombi are then found whose structure is frequently that of the tumor, and whose connection with the same is direct through the perforated wall of the vessel. These features in the growth of tumors lead directly to the consideration of the means by which multiple tumors appear in remote parts of the body after a single tumor has appeared in a given locality, and after the removal of such a primitive growth.

The distinction between primary and secondary tumors is now so obvious that one is inclined to forget that the presence of numerous tumors at various parts of the body was at one time regarded as evidence of the constitutional or dyscrasic nature of the morbid growth. Such a multiplicity seemed to indicate that the blood was charged with the constituents of the tumor, which were deposited at various parts of the body.

Although certain multiple tumors may be present in different localities without an apparent relation between an antecedent and a subsequent growth, such tumors are usually limited to certain systems of the body. Multiple bony tumors are found growing from bones, fibrous and warty tumors from the skin, and fibro-myomata from the uterus. Cohnheim's theory of the embryonal origin of tumors may seem applicable in such cases, but the frequent association of the osteomata with chronic inflammatory conditions, of cutaneous warts and fibrous tumors with local irritative processes, makes such a hypothesis unnecessary.

Those tumors whose multiplicity is of the greatest clinical importance are the rapidly growing forms terminating fatally. Such are those which reappear in the scar after the removal of a cancer, or in the adjoining chain of lymphatic glands or at remote parts of the body. The most satisfactory explanation of their presence, and of the generalization, recurrence, or metastasis of tumors, is derived from what has already been stated with reference to the manner of the growth of the latter.