ERYTHEMATOUS AND SCALING SKIN DISORDERS. I. Pityriasis rosea, eczematide, pityriasis lichenoides.

Abstract

Scaling is an elementary lesion of the skin, that follows an erythema persisting for some days. Scaling is due to an accelerated reproduc­tion of the epidermal cells, which is caused by the vasodilatation of the papillary plexus charac­terizing erythema. Scaling may be observed during the remission phase of numerous skin diseases, from actinic erythema to exanthemata. On the other hand, in erythematous and scaling skin disorders, desquamation is an important component precociously superimposed to inten­sely erythematous patches. In this chapter we will treat pityriasis rosea, eczematides, pityriasis lichenoides, patch para­psoriasis and psoriasis. We will not talk about pityriasis versicolor, which is very rare in childhood. Even patch parapsorias does not practically exist in the first decade, but some cases may occur in the second decade. Psoriasis is slightly less frequent in children as compared with adults. Pityriasis rosea and pityriasis liche­noides affect the same age group. They are rare before the third year and after the third decade. Eczematides are more frequent in children than in adults.