Erythrosquamous diseases

This term is used to describe etiologically different, usually chronic, scaling diseases characterized by erythematous, papular or plaque-like skin manifestations.

The following clinical pictures are subsumed under it:

• Psoriasis vulgaris
• M.Reiter
• Pityriasis rubra pilaris
• Parapsoriasis group
• Pityriasis lichenoides (Parapsoriasis guttata)
• Pityriasis rotunda
• Parapsoriasis en plaques
• Parakeratosis variegata
• Porokeratoses
• Pityriasis rosea
• Erythroderma

"Erythrosquamous" is a purely morphologic criterion. Erythematosquamous says nothing about the etiology of a clinical picture. The syndromes grouped under this heading have only one thing in common and that is chronic inflammation of the skin associated with a desquamative epithelial reaction. Eczematous" dermatitis also fulfills this criterion. However, it is not included in the category of erythematosquamous skin diseases.

The so-called parapsoriasis group was already separated as an independent group in 1902 by the dermatologist Louis Jean Brocq, who was born on 1.2.1856 in Timbaut near Agen/France and worked at L'Hôpital Saint Louis in Paris. Brocqu's concept also did not prove to be conceptually viable in the following period.

On the one hand, the diseases of the parapsoriasis group have no nosological relationship to psoriasis. On the other hand, there are no pathogenetic similarities among them. The large focus inflammatory parapsoriasis en plaques is an initial cutaneous T-cell lymphoma. Also, the name "parakeratosis variegata" has only historical significance today. This poikilodermic clinical picture is assigned to the group of "large focus parapsoriasis en plaques" and is often associated with a cutaneous T-cell lymphoma. The clinical aspect with the "striated or reticular arranged, lichenoid and atrophic, poorly scaling papules and plaques does not justify a separate entity.

In summary, "erythemato-squamous" is a descriptive term. It is possible that a common pathogenetic concept was originally intended when diseases were grouped under this title. However, this is not the case, as can be shown by the example of parapsoriasis or pityriasis rosea as a viral infection.