Cold abscesses have not only a significance of their own, but for the most part an identity. Their distinguishing feature is a limiting membrane, which forms whenever sufficient time has elapsed. Much has been written about it, and much error has been perpetuated with regard to it. This is the membrane formerly considered and called pyogenic, under the misapprehension that by it the pus or contents of the abscess were produced. I desire to emphasize in every possible way that this is a mistake. This membrane does not act to produce pus, but is rather the result of condensation of cells around the margin of the tuberculous lesion, forming, as it were, a sanitary cordon, for the absolute and definite purpose of protection against further ravages. I would suggest that the term pyogenic membrane be abolished, there being no such membrane under any circumstances, and that, this be known as that which in effect it is—namely, a pyophylactic membrane. It is a protection against pus, and were it not for its presence there would be no limit to the spread of tuberculous invasion. A lesion thus surrounded is shut off from most possibilities of harm, rarely encroaches, except by the most gradual processes, and, on the contrary, often contracts and reduces its dimensions, the watery portion of its contents being gradually absorbed and the more solid and cellular portions becoming condensed into matter which undergoes caseous degeneration, so that eventually recovery may ensue as the consequence of a metamorphosis of an original cold abscess into a caseous nodule surrounded by the old pyophylactic membrane, which is now serving as a capsule.
The contents of the cold abscess are, in some instances at least, of acute origin, and consequently may have been originally pus or its near ally. On the other hand, in cases which have occurred very slowly this material is not real pus, but is a semifluid debris having certain properties which remind one of pus. It has been my effort hitherto to devise for this material a name which should distinguish it from pus and indicate what it really is. Inasmuch as most of it has been of a puruloid character, at least at one time, I have suggested that it be called archepyon (i. e., originally pus or puruloid). As this flows from such a cold abscess, it is more or less watery and contains caseous, sometimes calcareous, nodules in masses of considerable size, and not infrequently sloughs of tissue and old shreds of white fibrous tissue which resist decomposition for a long time. This material has been thus imprisoned, sometimes for months or even years, and consequently has lost most of its resemblance to what it was originally. The organisms which first produced it have long since died, and it is practically sterile. If any organisms survive, they are the tubercle bacilli, which are more resistant and tenacious of life than the ordinary pyogenic organisms. This is why most culture experiments fail, and why even inoculation with the contents of an old cold abscess is often without effect even on most susceptible animals. Nevertheless the bacilli which the semifluid contents do not contain may yet linger in the meshes of the pyophylactic membrane; and here lurks the greatest danger in dealing with these lesions.
In old cases the pyophylactic membrane is very tough and very adherent by its outer surface. It can sometimes be peeled off in strips of considerable extent, at other times cannot even be separated, or sometimes is so placed as to render it impossible to follow it to its termination. There must be complete extirpation of this membrane, or at least destruction; and when its removal is impracticable, failure to remove it should be atoned for by some powerful caustic, such as zinc chloride, nitric acid, caustic pyrozone or the actual cautery, which should be made to follow it to its ultimate ramification. The membrane and the tissues underlying, when thus cauterized, will separate as sloughs, and these will be replaced by presumably healthy granulations, which should be encouraged until the original cavity is filled or the surface healed.
Acute abscesses, as indicated in the previous chapter, have no real limiting membrane, although there is more or less condensation of tissues about the focus of infection. A typical membrane is distinctive of tuberculous abscesses, and is to be regarded always as their natural protection and a barrier against their further encroachment—a membrane whose inner surface may harbor active organisms which cannot escape through its outer texture. Consequently, to simply incise it or inefficiently scrape it is to do a worse than useless thing; and one should never attack it unless he is prepared to extirpate it or destroy its integrity, and in this way dispose of it.
Cold abscesses when near the surface cause a bluish or dusky discoloration of the overlying skin, while the superficial and subcutaneous veins of this region are usually enlarged. Fluctuation is also a prominent phenomena in connection with them when they can be palpated. Deep collections of this kind may be mistaken for cysts or tumors, in which case the aspirator needle may be used to facilitate diagnosis. They vary in size from the smallest possible collection of fluid to abscesses which may contain a gallon or more of puruloid material or archepyon. They are known often as gravitation abscesses, because by the weight of the contained fluid they tend to elongate or spread themselves in the direction in which gravity would naturally carry a collection of fluid. Thus cold abscesses originating from tuberculous disease of the lower spine frequently work their way along the psoas muscle and present below Poupart’s ligament as psoas abscesses, or elsewhere about the thigh, while those which come from similar disease of the uppermost cervical vertebrae may present behind the pharynx, as the so-called retropharyngeal abscesses, and those from the dorsal spine present not infrequently as lumbar abscesses. These are but two or three familiar examples of what may occur in any part of the body.
Treatment.
—Aside from the treatment of cold abscesses, already indicated by radical measures, other means have been suggested, and particularly for the treatment of those in which such extreme measures are impracticable or impossible. It is sometimes efficacious to simply tap or remove by aspiration the contents of such a cavity. It may never refill, or but slowly, and after repeated tapping alone a very small percentage of such cases will subside into inactivity and the lesion be subdued, if not absolutely cured. Treatment by injection of emulsions of iodoform has found favor with many surgeons. I have never been able to secure the good results reported by others, and consequently have abandoned it; yet it deserves mention here because of the repute it has enjoyed.
This is based upon the alleged specific properties of iodoform as being peculiarly fatal to tubercle bacilli, presumably by liberation of free iodine. A cavity to be thus treated should be first emptied as completely as possible, after which may be thrown into it a glycerin emulsion or an ethereal solution, or a suspension in sterilized oil of 5 to 10 per cent. of iodoform. From 25 to 200 Cc. of some such preparation is introduced, while the walls of the abscess are more or less manipulated in the endeavor to completely disseminate the mixture. The cannula through which it has been introduced is then withdrawn; and this can usually be done with but little unpleasant iodoform effect. This is due to the pyophylactic membrane, which limits the activity of the drug as it has done that of the previous contents of the abscess. Such cavities have also been treated by washing out through a trocar with an injection of various antiseptic or stimulating solutions, among which may be mentioned hydrogen peroxide, weak iodine solutions, etc. My own advice is to treat all tuberculous lesions radically when such measures are not contra-indicated by their multiplicity or by too great depression of the patient, and so long as lesions are accessible to ordinary operative procedures. This same advice pertains also to those which have already spontaneously evacuated themselves, or where the overlying skin is threatening to break and permit escape of contents. Almost any case where this is imminent is one in which the surgeon, as such, ought to interfere. On the other hand, in deep collections and in debilitated individuals the treatment by injection may be tried.
The best way to treat accessible tuberculous lesions is by extirpation, as this hastens convalescence and leads to more permanent results.