The histopathology of the diseases of the skin / by P.G. Unna.

  • Unna, Paul Gerson, 1850-1929.
Date:
1896
Catalogue details

Licence: Public Domain Mark

Credit: The histopathology of the diseases of the skin / by P.G. Unna. Source: Wellcome Collection.

    55/1250 (page 17)
    during the intercurrent period of stagnation, properly nourished, and necrosis gradually supervenes (decubitus). We observe hypostatic hypersemia most commonly on the legs of those persons whose profession compels them to stand constantly, in men more rarely than in women, in whom the compression stagnation of pregnancy is often added. In particular the vessels of the skin of the leg, in lesser degree of the ankle and knee joint, and rarely of the foot and thigh, present a series of characteristic changes, which are by no means so simple as usually supposed. Gravity undoubtedly acts on the blood column in the arteries increasing the pressure just as in the veins, accelerating the one, delaying the other. It alone brings about a similar condition of over-filling in the capillaries, particularly in the feet as, in much higher degree, does the cupping glass. To the first, usually transient period of muscular insufficiency of the vessels, there rapidly succeeds a second period of compensation, in which the earlier difficulties are completely overcome. The heightening of the tone of the arteries as well as that of the veins brings on this compensation in the simplest manner, but not of course without at the same time markedly increasing the resistance to the whole circulation of the leg. And on this point depend all those later symptoms of disturbed compensation, which, as varix and ulcer of the leg, are so familiar. The much diminished “ Yis a tergo ” allows the blood of the large veins to sink as far as the valves of the subcutaneous veins of the legs. The stagnation in this third period, when cases usually come for treatment, is consequently, from its development, a hypostatic hypersemia. Therefore the centrally lying parts of the dilated venous trunks are swollen by pressure on them (Trendelenburg), and not the peripheral, as in ordinary stagnation hypersemia. Next the valves are distorted, the veins above them dilated and twisted through stretching. At the seat of the valves there are formed, with disappearance of the muscular and elastic coats, sack-like dilatations; the varices. At this stage the process may long remain stationary ; and even by limited coagulation in the varix, and consequent organisation or caseation, lead to a diminution of the open venous canal, and thus to relative recovery. On the other hand under favourable circumstances, or with artificial aid (constant compression), the dilated venous walls may be strengthened by the formation of new fibrous tissue, and the results of hypostatic hypersemia on the leg partly compensated. But there developes, in a large number of cases, in addition to an insufficiency, an organic resist¬ ance, supplied by the valves and the hypertrophied walls of the varicose veins, and now ensues a capillary stasis in the whole under extremity, or certain cutaneous areas—the fourth period. There are certain weak points of this region, where the results of the permanent stagnation are B