Selected monographs on dermatology / P.G. Unna [and others].

Date:
1893
Catalogue details

Licence: Public Domain Mark

Credit: Selected monographs on dermatology / P.G. Unna [and others]. Source: Wellcome Collection.

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    rated from the capillaries backwards, after being extremely narrowed for some time by external pressure. This atrophy, due to pressure, follows abnormal stretching of the muscular and elastic tissue of the skin, as in cases of long-standing scleroderma, pruriginous eczema, and ichthyosis, as well as in cases of prolonged pressure from atheroma, uric acid con- cretions, and chronic cedema. Obliterating atrophy, after thinning of the vessels by traction, we find in cicatrisations, and especially in the strise gravidarum. Syphilitic processes, on the other hand, cause a peculiar affection of both the larger and the smaller vessels—but chiefly of the former, in which a more or less cellular connective tissue is developed within the lumen, from the endothelium. Proceeding as it does with sclerosis of the already existing connective tissue, the production of large anaemic tumours of cartilaginous hardness may be the result. Anaemia lio- dermia may be similarly produced, but without sclerosis of the connective tissue, in the extremities of certain patients with tabes; and, in the same way, are initiated changes which lead to a whole host of fibrous hypertrophies and atro- phies, as in sclerosis of the skin, morphcea, and keloid. In all these cases there has been no preceding pressure or trac- tion ; the obliteration of the vessels does not follow but pre- cedes the existing anaemia. II. General Considerations concerning the Hyperemias of the Skin.1 The various anaemias of the skin are, upon the whole, of a very uniform character, because in them there is no very great departure from the normal state of the circulation. The general term hyperaemia, on the other hand, includes conditions differing considerably from one another, and to understand them clearly it is necessary always to have the physiological facts of the cutaneous circulation in one's mind. The appended diagram indicates the nerve-tracts concerned in the regulation of the blood-flow through the skin. 1 Allgemeines iiber Hyperainien der Haut —' Monatsh. f. prakt. Derm.,' is Bd., 1889, No. 2.