NÆVUS, a mole on the skin, generally called a mother's mark; also the tumour known by the name of a wen.
All preternatural tumours on the skin, in the form of a wart or tubercle, are called excrefences; by the Greeks they are called aerosthymia; and when they are born with a person, they are called nevi materni, or marks from the mother. A large tumour depending from the skin is denominated sarcoma. These appear on any part of the body: some of them differ not in their colour from the rest of the skin; whilst others are red, black, &c. Their shapes are various; some resembling strawberries, others grapes, &c. Heister advises their removal by means of a ligature, a cauter, or a knife, as circumstances best suit.
As to the tumour called a wen, its different species are distinguished by their contents. They are encysted tumours; the matter contained in the first three following is inspissated lymph, and that in the fourth is only fat. Mons. Laitre was the first who particularly described the fourth kind; and to the following purpose he speaks of them all. A wen is said to be of three sorts, according to the kind of matter it contains: those whose contents resemble boiled rice, or curds, or a bread-poultice, is called atheroma; if it resembles honey, it is named meliceris; and if it is like suet, it is denominated stomatoma; but there is a fourth sort, which may be called lipoma, because of its fat contents resembling grease. He says that he has seen one on the shoulders of a man, which was a thin bag, of a tender texture, full of a soft fat, and that it had all the qualities of common grease. And though the fat in the lipoma resembles that in the stomatoma, yet they cannot be the same: for the matter of the stomatoma is not inflammable, nor does it melt; or if it does, it is with great difficulty and imperfectly; whereas it is the contrary with the lipoma. When the man who had the above-named lipoma was fatigued, or had drunk freely of strong liquors, his lipoma was inflamed for some days after, and its contents rarefying increased the size of the tumour.
The lipoma seems to be no other than an enlargement of one or more of the cells of the adipose membrane, which is filled only with its natural contents. Its softness and largeness distinguish it in general from the other species, though sometimes the fatty contents will be so hard as to deceive. As this kind of wen does not run between the muscles, nor is possessed of any considerable blood-vessels, it may always be cut off with ease and safety.
As to the other kind of wens, their extirpation may or may not be attempted, according as their situation is with respect to adjacent vessels, the wounding of which would endanger the patient's life.