CHAPTER XXX

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INJURIES AND DISEASES OF THE LYMPH VESSELS AND NODES.

An appreciation of the pathology of the lymphatic system requires a brief allusion here to the latest investigations and conclusions regarding the purpose of the lymph as a fluid and the channels by which it is distributed. Under the term lymph, Hall has included four different types: (1) Tissue lymph, which fills the intercellular spaces throughout the body; (2) circulating lymph, which passes through the lymphatic capillaries into the circulatory system by way of the thoracic duct; (3) chyle, or the peculiar circulating lymph of the intestinal tract, which carries into the general circulation its load of nutritive material; (4) serous lymph, _i. e._, the contents of the serous cavities. Closely related to the latter are the aqueous humor, the cerebrospinal and the synovial fluids. All these fluids, except chyle, contain at least 95 per cent. of water and nearly 4 per cent. of proteids.

The lymph is the only fluid which comes into contact with all the living cells of the body; it pervades every part of its substance to such an extent that it has been said that the higher animals are essentially aquatic because they practically live in a watery medium. Blood normally comes into contact only with the endothelial cells of the vessels and with those cells in the splenic pulp and perhaps other localities which have to do with its elaboration, and these are but a minute proportion of the total cells of the body. All the rest receive their nutrition and even their oxygen through the lymph, which receives them from the blood. Moreover, nearly all the waste materials of the body are emptied into the lymphatic system, and thus directly or indirectly find their way into the blood to be further extruded. Thus, with the exception of the endothelium, the lymph is the medium of exchange between blood and tissue. In this the lymph and the lymphatics play a role which even for the surgeon must be of the greatest importance.

The amount of lymph which empties into the vena cava from the thoracic duct represents only that which comes from the viscera, bearing its special load of nutritive material. When we consider the communication between the blood-vascular and the lymph-vascular systems, the promptitude with which material injected into the tissues (_e. g._, salt solution) is taken up by the lymphatics and its effects made known through the bloodvessels, we will better appreciate how deleterious material also can be quickly distributed through the system. The lymph then must be regarded as a fluid derived from the blood by combined filtration and osmosis, which makes its way back into the blood again with equal ease.

Lymph vessels which are sufficiently large to be recognized have thin walls and are provided with valves like the veins, the lymph stream being propelled by a _vis a tergo_ from the heart. Any injury which permits blood to escape will also injure numerous minute lymph vessels; in fact, in such little maneuvers as vaccination the attempt is made to draw lymph alone and not blood. If a large lymph trunk be divided there may be an outpour of lymph, and if this happen to be the _thoracic duct_ the external escape of its lymph stream may seriously interfere with nutrition. Injuries which divide it within the thorax are usually fatal, but it may be divided in the neck by a puncture or stab wound, or during a deep operation. Escape of lymph into the abdominal cavity under similar circumstances gives rise to _chylous ascites_, and when into the thorax to _chylous hydrothorax_. In the former case repeated tapping may tide over the emergency and lead to eventual recovery; in the latter, aspiration or even open incision may be necessary. When the thoracic duct has been injured in the neck it may be possible to close the opening with sutures or to suture tissues over it. In a few instances final recovery has followed the formation of a _chylous fistula_. Injury to this duct is to be recognized by the flow of milky (_i. e._, chylous) fluid from the wound or from the duct itself. When poured into the abdomen or the thorax the retained fluid has the same milky appearance. It has been suggested to withhold all food in order to favor the spontaneous closure of such an opening, supporting the patient meanwhile by rectal nourishment and by the introduction of milk into the veins. The right lymphatic duct is less liable to injury, and such lesions on the right side would be of less importance.

[Illustration: PLATE XXXI

Diagram of the Nodes and Vessels of the Head and Neck, showing the Regions that are Drained into Each Group of Nodes. Deep structures in red, superficial in black. (Gerrish.)]

[Illustration: PLATE XXXII

Diagram of the Nodes of the Right Upper Limb and their Superficial Tributaries, showing the Areas Drained by Each Group. Deep structures in red, superficial in black.

Diagram of the Superficial Inguinal and the Popliteal Nodes of the Right Side and their Superficial Tributaries, showing Areas Drained by Each Subgroup. Deep structures in red, superficial in black. Frequent variations in dotted lines. (Gerrish.)]

[Illustration: PLATE XXXIII.

Diagram of the nodes of the trunk and their tributary vessels. (F. H. G.)]

THE ARRANGEMENT OF THE LYMPH VESSELS AND NODES.

Inasmuch as most of the surgical infections, including cancer, are disseminated by means of the lymph vessels it is necessary that the surgeon should know the relation of vessels and nodes to the other parts of the body. The surgical anatomy of the lymphatics can be appreciated by reference to Gerrish’s admirable diagrams. (See Plates XXXI, XXXII, and XXXIII.) They will indicate at a glance what it would take pages to describe. The reader should also make frequent reference to these diagrams in connection with studies of septic infection, tuberculosis, and especially of cancer.

OCCLUSION OF LYMPH VESSELS.

Occlusion of lymph vessel; may be either _congenital_ or _acquired_. The congenital type is of extreme interest pathologically, but perhaps of less interest to the surgeon, since it rarely permits of a surgical remedy. The reader interested in this subject should consult the writings of Busey, who has contributed memorable monographs on the general subject of occlusion of the lymphatics. The acquired forms have to do with various conditions, such as thickening of vascular walls, the pressure of exudates or of tumors, or even of callus, and with the specific infections, of which syphilis and cancer are perhaps the most illustrative. The result which is brought about by these various causes is not so much the dilatation of the vessels as the saturation or water-logging of the tissues on the distal side of the obstructive lesion. The former is indicated by the formation of vesicles or bullæ which will frequently ooze or weep continuously. Should the pressure be localized and circumstances favor it, a truly cystic collection of fluid may result. The more common type is the so-called _lymphedema_, which, when chronic, is always accompanied by hyperplasia of the affected tissues, their overgrowth resulting from a superabundance of nutrition, the connective tissue apparently appropriating the larger amount of this material for itself. Therefore with the dimensions of a member enormously increased it will be found that almost every other tissue except the connective has been starved out. Lymphedema differs from that produced by venous obstruction by its obstinacy and the density of the infiltration; in fact, it has been sometimes spoken of as solid edema. If it continues for some time there are permanent changes which do not admit of later dispersion, and permanent enlargement is the result. The most unmistakable expressions of this kind occur in the legs and the external genitals of both sexes (Fig. 184).

[Illustration: FIG. 184

Lymphedema.]

When compression, position, massage, and such measures fail the only other resort is amputation.

LYMPHANGIECTASIS AND ELEPHANTIASIS.

These terms refer to dilatation of the lymphatics, with a minimum of actual obstruction, often as a sequence of some previous lesion which has disappeared. In some of its expressions the condition is a manifestation of a widespread general disease or a parasitic infection. This is particularly true in those forms due to the presence of filariæ in the blood, in which it is not a question of the obstruction of one of a series of vessels, but plugging of a number of them by the adult worms, which reside especially in the larger lymph and chyle passages, sometimes even causing the appearance of chyle in the urine.

_Elephantiasis_ is an expressive term given to any enormous enlargement of a part of the body, due to a combination of causes, of which lymphatic dilatation and obstruction together constitute the most important feature. The so-called congenital forms may have to do with congenital deviations from the normal standard, but should be differentiated from instances of gigantism, which have already been alluded to in