THESE Tumours borrow their Names from a Cyst or Bag, in which they are contained; and are farther distinguished by the Nature of their Contents: If the latter forming them resembles Milk-Curds, the Tumour is called Atheroma; if it be like Honey, Meliceris; and if composed of Fat, or a suety Substance, Steatoma. The two first are not readily distinguished from one another, but their Difference from the Steatoma is easily learnt by their Softness and Fluctuation. These Tumours appear in every Part of the Body, and in Places where there are no Glands which, with the Circumstances of their Composition continuing always the same from their first Formation, agrees but little with an Opinion some of the Moderns are so fond of, that this kind of Swelling is an obstructed Gland whose Membrane forms the Cyst, and whose Fluids, when they burst out of their Vessels after a long Obstruction, make the Matter contained.

The Steatoma is never painful, 'till by its Weight it grows troublesome, nor is it a Mark of general Indisposition of Body; so that the Extirpation seldom fails of Success. The Size of some of them is very large, frequently weighing five or six Pounds, and there have been Instances of their weighing above forty.

When the Steatoma is irregular in its Surface, with Eminencies and Depresson, it is suety; whereas the fat one has for the most part a uniform smooth Outside. The Operation for the Steatoma will be understood by the Description of that for the Scirrhus.

The Atheroma is much more common than the Meliceris, at least, if all encysted Tumours with Matter not curdled, may in compliance with Custom, be called so: These are more frequent and grow larger than those where the Matter is curdled, being often attendant on scrophulous Indispositions, which makes them more difficult of Cure.

The Cysts of these Tumours, with the Skin covering them, after a certain Period of Growth, refilling any further Enlargement, do frequently inflame and break; but this Opening is not so advantageous for the Cure, as Extirpation by the Knife, which should be done in the Infancy of the Swelling. When the Tumours are no bigger than a small golden Pippin, they may be dissected away from under the Skin, by making a straight Incision only through it; but if they exceed this Bulk, an oval piece of Skin must be cut thro' first, to make room for the Management of the Knife and taking away the Tumour; in which case, it will be adviseable to take off the upper Portion of the Cyst with the Skin and then by the Help of a Hook to dissect away as much of the Remainder of it as can be conveniently, which is a less painful, and more secure Method than destroying it afterwards with Escharoticks: This Rule is to be observed, when the Cyst runs so deep amongst the Interstices of the Muscles, as to make it impossible to remove the whole of it, where if we cut off a great Quantity, the, rest usually comes away in Sloughs and Matter. I once opened a remarkable Atheroma of this kind; it was about as big as the Crown of a Man's Hat, and lay underneath the Pectoral Muscle (as all I ever met with on the Breast have done) extending itself towards the Armpit, amongst the great Vessels, and pressing against the Clavicle: I cut away a large circular Piece of the Skin, Pectoral Muscle, and Cyst, but did not dare to touch the lower Part of it, which I could not remove without laying the Ribs bare; however, it separated in the Digestion of the Wound, which for some time discharged excessively, and the whole Cavity filled up, leaving him the Use of his Arm almost perfect: After this, two or three thin small Splinters of the Clavicle worked away through the Skin, but without any great Inconvenience.

The Ganglion of the Tendon is an encysted Tumour of the Meliceris kind, but its Fluid is generally like the White of an Egg; when it is small, it sometimes disperses of itself; Pressure, and sudden Blows, do also remove it, but for the most part, it continues, unless it be extirpated: It is no uncommon Case to meet with this Species of Ganglion, running under the Ligamentum Carpale, and extending ifself both up the Wrist and down to the Palm of the Hand. The Cure of this Disorder cannot be effected but by an Incision through its whole Length and dividing the Ligamentum Carpale, which I have performed successfully several times.

The Dressing in these Cases does not at all differ from the general Methods of treating Wounds.