CYST. Kystus, (swerve, bladder). Certain membmnous investments, of various forms, though commonly spheroidal, being shut sacs, and developed in the midst of other tissues, have obtained the name of cysts.
Up to the present moment the study of cysts is so little advanced that we can scarcely dis cover any researches which would appear to be founded upon the observation of nature. Whilst so much attention has been devoted to the in vestigation of many departments of patholo gical anatomy, it is difficult to understand why this very interesting subject has been compara tively neglected. The singularity of the cir cumstance is not lessened by the reflection that the rules of therapeutics ought to vary with the character of these sacs, and that, consequently, the anatomical study is of first-rate importance in enabling us to proceed rationally in the treat ment of these extraordinary products of the ani mal economy.
In describing these organs, two modes have commonly been employed ; the one, to con sider them with reference to the product they contain ; the other, with reference to their pro per structure. It is not our intention to adopt either of these methods of considering the sub ject, and for the following reasons :—it is de monstrable that cysts which are identical in texture frequently envelope totally different products, and also that the products and the cysts are susceptible of transformation to an almost indefinite extent ; and as neither method affords us any facility in distinguishing one kind of cyst from another, we hold them alike inadequate to lead to correct views of the sub ject. The plan which we propose to follow may not afford any increased facility in dia gnosis, but it is, we apprehend, founded upon a more stable basis than either of those to which allusion has been made. We mean to consider cysts with reference to the mode of their development; and although we do not pretend that this arrangement will afford much greater facility than at present exists for the diagnosis of the species, yet it appears to us to be the most natural classification which, in the present state of our knowledge, we are enabled to offer. A considerable assistance in the dia gnosis of these organs may be obtained from the adoption of the following principles, which, though not unerring in their application, will afford a very near approximation to the truth, in the majority of cases. Those eysts which
are external, subcutaneous, and exactly glo bular, with a thinning of the dermis, which seems to adhere to their surface, commonly contain sebaceous matter of a whitish colour, friable and semi-concrete ; those which occupy muscular interstices in the neck, the back, or the extremities, have, commonly, thin parietes, are cellulous, of irregular form, and contain either serosity or albuminous pus, in which are seen floating opaque flocculent particles ; those which surround articulations and ten dinous sheaths—true appendices of synovial tissues—are strengthened externally by fibrous lamin, lined by a serous tissue, and contain a more or less pure synovial fluid ; those which are developed under the anterior annular liga ment of the carpus sometimes contain small whitish bodies, in appearance not unlike a grain of boiled rice; those which occupy in ternal cavities, attaching particularly to the liver, usually contain hydatids, and to the ovary contain a variety of products, sometimes serous, sometimes sanguinolent, sometimes gelatinous.
Until a better method of diagnosis is pre sented, the situation of the organ will therefore facilitate to some extent the knowledge of its contents. No one, however, will rest satisfied with this means, nor underrate the necessity of pursuing the investigation of these organs, until we are in a condition to state with more cer tainty the elements for their dia9.-,nosis.
We believe that all cysts may be ranged under one of the three following categories. A cyst may be a simple enlargement, or exagge rated developement, or other modification of an existing organ. It may be produced by the irritation excited by the presence of a foreign body, whether that body be a shot or other substance introduced from without, or a tu bercle or other abnormal product developed within the body. It may be a new formation not before existing in the economy, and pre existent to the matter which it may be after wards found to contain.