Part 20

As the original cancer is considered as possible only in parts where epithelium is a normal constituent, so the primitive sarcoma is possible only in parts where connective tissue is present. The apparent great frequency of sarcoma in recent times is thus obviously explained. With an agreement as to its histological characteristics, its possible place of origin is any of the connective tissues of the body, and their presence is universal. In the manner of its growth, its recurrence, and generalization it is subject to the same laws which determine similar events in the history of cancer. Its degenerations are often the same, and its symptoms are due to the action of like causes.

The importance of distinguishing between these atypical tumors is real, in that it is only through the association of causes, symptoms, and results with defined and constant characteristics that a practical knowledge of tumors is to arise. The time-honored distinction between malignant or semi-malignant and benignant growths is always to be sought for, and can only be fully possessed when the natural history of the new formations is known. With an exact appreciation of the structure of a tumor it becomes possible to study its special pathology. From a knowledge of the latter are to be derived those features of importance in determining the relation of morbid growths to other deviations from normal and physiological processes. An immediately practical benefit arises from the Thiersch-Waldeyer modification of Virchow's theory of the origin of tumors, in that it permits with greater ease a more accurate clinical diagnosis. Lücke has been prominent in calling attention to the suggestions thus presented.

The diagnostic value of the theory above-mentioned is rather negative than positive. With rare exceptions, a tumor cannot be epithelial in character if its origin is from an organ or a part in which epithelium is absent. The possible exceptions admit theoretical explanations which present considerable degrees of probability, and are also based upon the existing views of the development of tissues.

A tumor whose origin from the connective tissues is determined partakes of the characteristics of its matrix, and is a connective-tissue tumor. Its development from fibrous tissue is more likely to result in a fibroma; from fat tissue, a lipoma, or a myxoma; from cartilage or bone, a chondroma or osteoma.

Tumors developing at certain periods of life in certain parts of the body are more likely to belong to one than another of the histogenetic groups. Tumors of the connective-tissue series are stated by Lücke as more prevalent before the age of thirty-five years, while those of the epithelial group are more likely to occur after this age, and cancer of the lip is of special frequency in old age. The fibro-myoma is of most frequent occurrence in the uterus, and rarely attains a large size till the approach of the climacteric.

The rapidity of growth of tumors is also associated with their genesis. It has previously been stated that the more rapidly growing tumors are those whose cells are most abundant and in the closest and most {120} intimate relation to blood-vessels. The type of such tumors is the sarcoma with its scanty intercellular substance, while the other (histoid) tumors in the same series, as the fibroma, lipoma, chondroma, etc., are of relatively slow growth. Tumors of the epithelial series are of slow growth, from the constantly increasing distance of the new-formed cells from the vascular connective tissue which provides their nourishment. When, however, the growth of the epithelium advances into the connective tissue, pushing out in all directions and coming in contact with new series of vessels, the opportunities for nutrition are favorable. In like manner, when the new formation concerns the connective-tissue stroma, as well as the epithelial sprouts, vascularization proceeds with the development of the tumor, and favorable conditions for rapid growth are presented. Large epithelial tumors may thus arise within organs, but, as the surfaces are reached, the sources of nourishment become farther removed and the degeneration of the epithelium favors its detachment and the formation of ulcers. Hence the tumors whose advance is associated with ulceration belong rather to the epithelial than the connective-tissue group.

The tendency of the cancerous tumors to become generalized through the lymphatics, and that of sarcomatous growths through the blood-vessels, is admitted as an important feature in the differential diagnosis. Although there are numerous exceptions, the rule is available. Its explanation is based upon the assumed inability of the larger epithelial cells of the cancer to pass through the lymph-glands; being detained, they serve as new centres of growth. The smaller cells of the sarcoma, on the contrary, are permitted a passage through the gland. The numerous and thin walled blood-vessels present in the rapidly growing sarcoma permit an extension of the latter into their interior, and thus a ready opportunity is offered for the formation of emboli.

Another important modification in the classification of tumors has resulted from the recent discoveries regarding the nature and effects of infective agencies. Virchow grouped together under the term granulomata certain growths composed of granulation-tissue occurring in syphilis, lupus, leprosy, and glanders. Their relation to inflammatory processes was very intimate, yet they were recognizable as tumors from their possession of many of the characteristics generally admitted as belonging to such morbid growths. Although at times their presence might be regarded as evidence of an inflammatory disturbance, their frequent appearance independently of general symptoms of the latter was apparent. These tumors, furthermore, were so frequently accompanied by inflammatory products as to suggest a like cause for both. Virchow stated that the recognition of the etiology of these tumors was indispensable to their separate consideration, and laid stress upon the presence of a specific virus, contagious and infectious, in the case of syphilis. His views concerning the etiology of leprosy, though more guarded, yet carried the suggestion of the importance of exact investigation concerning the assumed contagious character of this disease. The contagiousness of glanders was not only admitted, but the similarity of its manner of origin and propagation to the invasion of syphilis was also stated. Not only were the resemblances between glanders and syphilis recognized, but lupus, leprosy, tubercle, and scrofula were also admitted as presenting a similar relation.

{121} The importance of recognizing the etiology of these tumors rather than their anatomy as a basis of classification was strongly urged by Klebs, who proposed the term infective tumors for the group of granulomata, including syphilis, lupus, leprosy, and glanders; and for tubercle, scrofula and the pearly distemper of animals, which Virchow had classified as lymphomata. This group has been still further extended by the addition of the lymphomata occurring in typhoid fever, scarlet fever, and diphtheria. Ponfick has recently added the disease actinomycosis to the series, and Cohnheim suggests that certain of the lympho-sarcomata may be similarly classified.

The growths thus included have a common element of structure--the granulation-tissue, with its possible disappearance through absorption or its transformation into an abscess or dense fibrous tissue. Such features are those common to the granulation-tissue resulting from ordinary inflammation. Their essential characteristic, however, lies in the etiology of this granulation-tissue, and for many members of the group the cause has been discovered to be microscopic organisms. The constant presence of these is determined in sufficient numbers, in such distribution, and in such relation, as to explain the nature and occurrence of the tumors.

The evidence recorded is not equally full and exact for all members of this group. Neisser has discovered the bacillus of leprosy, and the discovery by Koch of the bacillus of tuberculosis, scrofula, and pearly distemper has already been referred to. Schütz and Löffler have lately announced their isolation of the micro-organism causing glanders, and Bollinger discovered the fungus whose presence is necessary for the existence of actinomycosis.

In the above affections the organisms are to be regarded as the characteristic active agent in producing the phenomena of the disease in which they occur. The presence of micro-organisms in syphilis, typhoid fever, scarlet fever, and diphtheria is admitted, yet their absolute identification and constant presence as a cause of the various manifestations of the respective diseases still remains to be proved.

The classification of tumors herewith presented is essentially that of Virchow, with such extensions and modifications as have arisen in consequence of the investigations and discoveries during the twenty years which have elapsed since the delivery of his memorable series of lectures. Cysts are mentioned, as well as growths, from the importance of the former in practical medicine. The frequent simultaneous occurrence of cysts and growths in the same tumor should be mentioned, and the cystic feature is usually indicated as a qualification.

CYSTS.

Cavities, either new formed or pre-existing, with various contents. The latter are blood, liquid other than blood, and gland-secretion or retained secretion. The wall varies in structure in accordance with the method of origin of the cavity.

{122} Hæmatoma.

A collection of extravasated blood, usually within the tissues. Examples, hæmatoma of the pericranium (periosteum), of the external ear, muscle, dura mater, ovary, broad ligament, vulva, anus, uterus (from retained placenta), hæmatocele, dissecting aneurism.

Hygroma.

A collection of transuded or exuded fluid in pre-existing or new-formed spaces. Examples, hydrocele, hydromeningocele, hydromyelocele, hydrencephalocele, ganglion, inflamed bursa.

Retention-Cyst.

An accumulation of retained secretion in follicles or canals from obstruction to its escape. Examples, atheroma and comedo of the skin, mucous cysts of the gastro-intestinal mucous membrane, ovula Nabothi, and cystic polypus of the uterus; retention-cyst of the antrum, vermiform appendage, gall-bladder, and bile-ducts; dropsical dilatation of the ovarian follicles, Fallopian tube, uterus (hydrometra), parovarium (cyst of the broad ligament); hydronephrosis and multilocular cystic kidney, spermatocele, ranula, galactocele.

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The growths are classified according to the tissues of which they are chiefly composed and from which they originate, and according to their etiology. There are consequently the connective-tissue group; that of tissues of higher function, as muscle, nerve, and vessels; and the epithelial group, in which the new formation of epithelium is the essential feature. The teratoid group comprises a more complex massing of tissues, representing a combination of those derived from all the germinal layers of the embryo. The infective group includes those tumors whose structure is closely allied to that of the products of inflammation, but whose origin is the direct result of the introduction from without of a microphyte.

CONNECTIVE-TISSUE GROUP.

Each member mainly composed of a more or less typical growth of a connective tissue:

Myxoma, Lipoma, Glioma, Chondroma, Fibroma (including papilloma and melanoma), Osteoma.

To these are added tumors composed of an atypical growth of a connective tissue, chiefly manifested by a predominance of cells:

Endothelioma, Sarcoma.