Although a few distinct organs or tissues have here been specifically considered in their relations to tuberculous disease, there is no organ or tissue in the body which is exempt from its ravages and in which evidences of tuberculous disease may not be found. Even the mammary gland occasionally presents tumors composed of tuberculous granuloma which more or less simulate malignant disease, while calling for the same radical treatment ([Fig. 22]).
Fig. 22
Gross appearance in tuberculosis of the mamma. (Dubar.)
Paths of Infection.
—The tuberculous virus may enter the body through various channels. Probably in the majority of instances it gains entrance through the respiratory tract, less often by the alimentary canal, and occasionally by air contact of open wounds or direct infection by local agencies. It is now well established that tuberculous disease is easily inherited, although a predisposition to its ravages is transmitted from parent to children.
In what this predisposition consists is not always easy to say. As the tubercle bacillus grows in the tissues, it is by preference an anaërobe, and it seems to be lowered in activity or banished by access of oxygen. It has been shown that in those individuals in whose pallid skin, long bones, flabby muscles, and pale conjunctivæ we recognize a predisposition to this disease, the heart is disproportionately small as compared with the weight and size of the lungs. This means a relatively feeble pumping power, and is perhaps the best explanation for what is accepted as a fact. The mucous membranes of the nose and throat are usually the first lodging places for germs carried by the air, they finding here the warmth and moisture necessary for their detention, development, and growth. As long as these membranes are unbroken and healthy, infection is rarely possible; but let tubercle bacilli become caught in the crypts of the tonsils or in adenoid tissue in the nasopharynx, and the other disturbance, set up by irritant organisms of various species, will usually bring about conditions favoring their growth and incorporation into the living tissues. This lymphadenoid tissue is often the port of entry for these organisms. The explanation for local and surgical tuberculosis in bones and other accessible tissues probably is connected with causes determining at these points an area of least resistance, in which the germs find tissues more susceptible than elsewhere, and in which they may live and thrive.
Not the least interesting and important of the considerations regarding tuberculous disease is the possibility of an acute outbreak of tuberculosis after long latent or chronic manifestations of the disease. This means, in effect, the onset of general miliary tuberculosis which soon terminates fatally, and death is not the infrequent result of such extremely rapid outbreaks from tuberculous disease of joints, bones, ovaries, etc. For the disease when it has assumed this extremely rapid type there is, so far as known, no relief.
Diagnosis.
—So far as the general recognition of tuberculous disease is concerned, it is not often difficult. It is accompanied usually by more or less marked cachexia (at least this is the case when infection is serious and widespread), one of whose principal characteristics is the so-called hectic (habitual) fever of old writers. This was a fever of a remittent type, accompanied also by more or less colliquative night sweats, with dryness of the skin during the daytime, and flushing of the face. Hectic fever, as a matter of fact, often accompanies tuberculous disease, but is seldom encountered until pyogenic infection has occurred and suppuration is taking or has taken place. There is now much reason to consider hectic fever as an auto-intoxication from absorption of morbid products. In advanced cases we may find evidence of amyloid changes, although these are seldom recognized prior to autopsy. It is seldom difficult to recognize tuberculous disease except when at a considerable depth. Here, as long as there is no suppuration, there is little tendency to leukocytosis, by which diagnosis as between sarcoma and tuberculous infection may perhaps be made. Sometimes when in doubt the exploring trocar or an exploratory incision may be resorted to, it being always best to be prepared at the same time to proceed with whatever further operative procedure the findings may indicate.