Selected monographs on dermatology / Unna, Nielsen, Duhring, Bronson, Blanc, Berger, Prince-Morrow.

  • New Sydenham Society.
Date:
1893
Catalogue details

Licence: Public Domain Mark

Credit: Selected monographs on dermatology / Unna, Nielsen, Duhring, Bronson, Blanc, Berger, Prince-Morrow. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

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    the larger blood-vessels. It seems probable that some of the haemorrhages of newly-born syphilitic infants are also due to imperfect development of cutaneous vessels, but true (embolic) purpura also occurs. The so-called cachectic haemorrhages, however, must not necessai-ily be attributed to atrophic or degenerative vascular changes. They chiefly belong to processes of diapedesis ; a cutaneous haemorrhage in a cachectic individual is hardly ever due to cachexia of the vessels. An affection of the general vascular system may be men- tioned, which alone deserves the name of a haemorrhagic diathesis, viz. haemophilia, in which Schonlein and others found a thinness of the vascular walls. The condition is hereditary, and the male members of the family, with thin, little pigmented skin and fair hair, are chiefly affected. Sponta- neous haemorrhages in the skin, without laceration of the cutis may occur; and the slightest mechanical injury may entail serious haemorrhages and haematomata. As there is no want of coagulating power in the blood, the difficulty of stop- ping the bleeding from insignificant wounds can only be the result of deficient retraction and elasticity of the arterioles. But here trauma is also the important exciting cause. In proceeding to the cutaneous haemorrhages resulting from diapedesis, we enter the wide and dark field of pur- puric diseases. Only in those occurring in simple venous congestion, have we a satisfactory experimental basis in the observations of Strieker, Cohnheim, Auspitz, &c. But these are of less interest to us than those occurring in connection with infective processes and neurotic disturbances. They have been generally classed as mechanical, in distinction to those forms of purpura supposed to be dyscrasic and toxic, and due to a change in the blood rather than of the condi- tions of the circulation. This idea, however, on careful in- vestigation, is untenable, for we may also give a 11 mechani- cal explanation to the toxic and infective forms. It is hence necessary to give the so-called mechanical forms of purpura another name. They mostly result from simple congestion (stagnation) ; and they are the simplest forms of cutaneous haemorrhage from diapedesis. Their prototypes from experimental pathology are the petechiae, which we can 3