It is remarkable that if the exostosis has been removed by operation, the same degree of certainty as to its not returning does not exist as when it has thus sloughed away. On the contrary, when the tumour has been completely extirpated and only the sound part of the bone left, a new growth is often formed with so much certainty and rapidity as to justify the expression we have already used, of its " grow ing again with an inveterate pertinacity." On this subject we recollect a story (told, we be lieve, by Bell) which might be considered as ludicrous if it was not buCtoo instructive. A dancing-master had exostosis on both tibia! ; they gave him - no inconvenience, but the de formity was intolerable to his eyes, and he thought it interfered with his popularity and therefore with his profits. He persuaded a surgeon to lay them bare and scrape them down to his ideas of genteel proportion, but unfortunately the surgeon forgot that bones could granulate and grow. They did so in this case, and after a long confinement and much suffering the last condition of the patient was worse than the first—the deformity was m uch increased.
We distinguish a node from a truly exostotic growth by the rapidity of its formation, by its becoming stationary when it has been formed, whereas the increase of exostosis is progressive and may be unlimited; by its being exquisitely tender to the touch ; its being subject to noc turnal exacerbations, and by its capability of being relieved or removed by medicine in a great number of instances. When composed of osseous material alone, the almost stony hardness of an exostosis will serve to distin guish it, and when of cartilage, it is lobulated or nodulated on its surface, which is never the case with respect to nodes.
There is a fungoid disease of the periosteum which, under particular circumstances, may be mistaken for exostosis, an error which we have witnessed, and which might be attended with serious consequences. It is fortunately of very rare occurrence, and as far as we know has not been hitherto described. In the four speci mens which have fallen within our observation, its situation has been in the periosteurn of the tibia.
During life, when covered by a dense and resisting fascia, the tumour is very hard, its growth slow, and not attended with much pain; neither is the use of the limb much impaired, as we have known a patient with this disease travel on foot a distance of six miles to the hospital. When not so restrained, its gros,vth is more rapid : it is softer to the feel, and has most of the external characters of malignant fungus. Frequently its surface is lobulated or
otherwise uneven, when it very much resembles exostosis. When the skin gives way and ulce rate3, or if the tumour is unfortunately cut into, a bleeding fungus protrudes, that runs rapidly into a gangrene, which involves the adjacent parts; and if the limb is not speedily removed, the patient dies.
When examined after death or removal, the tumour is found to be situated within the laminw of the periosteum. There is a speci men in the museum of the school in Park-street, in which-the membrane may be seen as if split, one layer passing in front of the diseased mass, and another still more distinctly, behind, be tween it and the bone. The consistence of the tumour is tolerably solid and firm, but not so solid as cartilage; its colour is white or gray, and its vascular org,anization apparently very deficient. This latter circumstance is very re markable, for in some instances these tumours exhibit a pulsatility scarcely inferior to that of an aneurism, a symptom that may render dia gnosis extremely Clifficult, and which cannot be explained by any post-mortem examination. The substance of the bone beneath the tumour is always removed by absorption to a consider able depth.
disease, as its name im plies, is a degeneration of the bone into a sub stance of a softer consistence, not, however, resembling flesh ; or rather it is an alteration of structure accompanied by a deposition of new material, and therefore attended by tumefaction to a greater or less extent. As such, it is evidently irremediable except by the knife, and if there is a disease of the osseous system to which the term malignant can be applied, it certainly is this. Its malignancy, however, has no resem blance to that of cancer or fungus hwmatodes, although like the latter it very frequently attacks persons in the earlier periods of life; but it does not involve adjacentstructures in a disease similar to itself, neither does it contaminate the system through the medium of absorption. The most terrific feature in its character is its ten dency to recur after its removal from one situa tion, being in this respect more formidable than cancer, which is in many instances, at first but a purely local disease, and may be extirpated with complete success. This predisposition to the disease is evidently constitutional, but as we are totally ignorant of the circumstances that conduce to it, and will probably remain so, it is wholly uncontrollable by medicine or medical treatment.