# 1911 Encyclopædia Britannica/Wart

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​WART (Lat. verruca), a papillary excrescence of the skin, or mucous membrane. The ordinary flat warts of the skin occur mostly upon the hands of children and young persons; a long pendulous variety occurs about the chin or neck of delicate children, and on the scalp in adults. Warts are apt to come out in numbers at a time; a crop of them suddenly appears, to disappear after a time with equal suddenness. Hence the supposed efficacy of charms. A single wart will sometimes remain when the general eruption has vanished. The liability of crops of warts runs in families. In after life a wart on the hands or fingers is usually brought on by some irritation, often repeated, even if it be slight. Warts often occur on the wrists and knuckles of slaughter-house men and of those much occupied with anatomical dissection; they are often of tuberculous origin (butchers' warts). Chimney-sweeps and workers in coal-tar, petroleum, &c., are subject to warts, which often become cancerous. Warts occur singly in later life on the nose or lips or other parts of the ​face, sometimes on the tongue; they are very apt to become malignant. Towards old age broad and flattened patches of warts of a greasy consistence and brownish colour often occur on the back and shoulders. They also are apt to become malignant. Indeed, warts occurring on the lip or tongue, or on any part of the body of a person advanced in life, should be suspected of malignant associations and dealt with accordingly. Venereal warts occur as the result of gonorrhoeal irritation or syphilitic infection.
A wart consists of a delicate framework of blood-vessels supported by fibrous tissue, with a covering of epidermic scales. When the wart is young, the surface is rounded; as it gets rubbed it is cleft into projecting points. The blood-vessels, whose outgrowth from the surface really makes the wart, may be in a cluster of parallel loops, as in the common sessile wart, or the vessels may branch from a single stem, making the long, pendulous warts of the chin and neck. The same kinds of warts also occur on mucous surfaces. It is owing to its vascularity that a wart is liable to come back after being shaved off; the vessels are cut down to the level of the skin, but the blood is still forced into the stem, and the branches are thrown out beyond the surface as before. This fact has a bearing on the treatment of warts, if they are snipped off, the blood-vessels of the stem should be destroyed at the same time by a hot wire or some other caustic, or made to shrivel by an astringent. The same end is served by a gradually tightening ligature (such as a thread of elastic) round the base of the wart. Glacial acetic or carbolic acid may be applied on the end of a glass rod, or by a camel-hair brush, care being taken not to touch the adjoining skin. A solution of perchloride of iron is also effective in the same way. Nitrate of silver is objectionable, owing to the black stains left by it. A simple domestic remedy, often effectual, is the astringent and acrid juice of the common stonecrop (Sedum acre) rubbed into the wart, time after time, from the freshly gathered herb. The result of these various applications is that the wart loses its firmness, shrivels up, and falls off. Malignant and tuberculous warts should be removed by the scalpel or sharp spoon, their bases, if thought advisable, being treated by pure carbolic acid.
A peculiar form of wart, known as verrugas, occurs endemically in the Andes. It is believed to have been one of the causes of the excessive mortality from haemorrhages of the skin among the troops of Pizarro. Attention was called to it by Dr Archibald Smith in 1842; in 1874, during the making of the Trans-Andean railway, it caused considerable loss among English navvies and engineers.  (E. O.*)