[Chronic inflammatory diseases of the skin / Extracted from his "Commentaries on Diseases of the Skin."].

  • Thomson, Anthony Todd, 1778-1849
Date:
[1839-1840]
Catalogue details

Licence: Public Domain Mark

Credit: [Chronic inflammatory diseases of the skin / Extracted from his "Commentaries on Diseases of the Skin."]. Source: Wellcome Collection.

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    and, in a few instances, confined to the legs. It is a very common disease of children, in every class of society: it dis¬ plays itself very early, and often increases with the years of the individual. It is confined to neither sex. It is not, to my knowledge, hereditary; nor is it contagious. Four species of Pityriasis are described in the Synopsis of Dr. Bateman ; namely, P. capitis, P. rubra, P. versicolor, and P. nigra*. I reject the two latter altogether from the genus, for the following reasons. P. versicolor does not seem to be the result of any inflammatory condition of the surface, either acute or chronic; and, as Rayerf properly remarks, it has a greater affinity with Cloasma than with Pityriasis. The P. nigra of Willan I consider altogether out of place here; for, although it is attended by a furfuraceous desquamation of the cuticle, yet it originates in a papulated state of the skin; consequently it rather approximates to Lichen than to Pityri¬ asis:]:. I am also of opinion that the P. capitis and P. rubra of Willan and Bateman are merely varieties of the same disease; consequently, that there is only one species of the disease, which may be named Pityriasis vulgaris. That variety of the disease which, regarded as a species, has been named Pityriasis capitis, may be aptly desig¬ nated P. alba. It appears most commonly in infancy and in old age. S. The first or inflammatory stage is so slight, that scarcely ever is it recognized until the desquamation, which is attended with itching, commences. The scratching which this induces detaches the scales; and these, becoming entan¬ gled in the hair, afford the first indication of the presence of the disease. If the head be then examined, patches of ex¬ tremely small, thin, white, dry scales will he seen scattered over the scalp, sometimes separate, at other times confluent, so as to cover a considerable portion of the surface (PI. 1, * Synopsis, 7th edit. p. 7l. f Traite Theorique et Pratique des Mai. de la Peau, t. ii. p. 56. ± The disease described hy Cazenave and Schedel, as it occurred in Paris in the years 1828 and 1829, which Dr. Green (Practical Compendium, p. 232) regards as a true Pityriasis nigra, I have never seen.