Observations on the various forms of superficial dermatitis : particularly erythema, eczema, psoriasis, lichen, and pityriasis rubra with cases / by P.H. Pye-Smith.

  • Pye-Smith, Philip Henry, 1840-1914.
Date:
[1881?]
Catalogue details

Licence: Public Domain Mark

Credit: Observations on the various forms of superficial dermatitis : particularly erythema, eczema, psoriasis, lichen, and pityriasis rubra with cases / by P.H. Pye-Smith. Source: Wellcome Collection.

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    contradicted by all we know of its course and origin, as well as by microscopical investigation of the scales and of the skin in section. Dr. Yandell, of St. Louis, recognised several of my cases as malarial in origin, but the evidence did not convince me. Form and distribution.—The form of psoriasis is remark- ably constant, and its distribution scarcely less so. It is always the dry, scaly tetter, always bilateral, and often exactly symmetrical, but never, I believe, universal. Symmetry has been said to prove that a disease is “ constitutional.” If this means only that it is not traumatic, it is true enough, but if it means that the symmetrical disease is due to some anomaly of the blood like leuchsemia, or to some generalised condition like carcinoma, I can see no justification for the dictum. The lesions of the skin in purpura, an affection of the blood and blood-vessels, and in syphilis, a generalised disease, are far less symmetrical than in psoriasis and idiopathic eczema, which are both strictly confined to a single organ. The two elbows are not covered with scales because they are both supplied with the same blood, for no part of the skin (or mucous membrane either) has its private supply of nourishment. The two elbows are affected with psoriasis because their skin is more alike than that of any other part of the body. Next in likeness is the skin over the knee caps, and least so the skin of the axillae. The varieties described as Psoriasis punctata, guttata, num- mulata, annulata, gyrata, &c., depend chiefly on the period at which the disease is observed, and are of no scientific, that is, of no practical importance. There is, however, one form of this affection which seems to me to be distinct enough in more than mere accident’s of appearance to deserve notice as a variety.1 (1) It is guttate in figure, the separate spots not coalescing as usual into larger patches; (2) there is little red- ness around the scales; (3) the distribution is much less regular than usual, the whole trunk being often spotted over and the elbows and knees free; (4) it scarcely itches at all; (5) 1 Since writing the above I have noticed in Dr. Liveing’s excellent ‘ Handbook of the Diagnosis of Skin Diseases/ p. 120, a very similar account of what he called Scrofulous Psoriasis.