Eczematous Dermatoses

Abstract

Eczematous dermatoses, that are everyday observations in clinical practice, are induced by various factors of an exogenous and endogenous nature, that generally act in combination. A helpful classification subdivides the various forms of eczema into exogenous (irritant contact dermatitis, allergic contact dermatitis, microbial eczema, dermatophytide) and endogenous (atopic eczema, nummular eczema, pompholyx, asteatotic eczema, gravitational eczema, pityriasis alba, juvenile plantar dermatosis, seborrhoeic dermatitis). However, it must be borne in mind that external triggering factors are associated with an inherited predisposition in the induction of a single disease. Nummular (discoid) eczema, that is not a precise etiological entity, is clinically characterized by coin-shaped or oval lesions with well-defined borders on the trunk and limbs. It is essential to stress that atopic dermatitis and allergic contact dermatitis can present with the same clinical aspects. Asteatotic (xerotic) eczema is usually observed in children and elderly subjects with minimal clinical signs (modest erythema and pityriasiforme desquamation) affecting most often the legs. Gravitational (stasis) eczema involves the lower third of the legs of middle-aged or elderly subjects. Pityriasis alba, that is characterized by hypopigmented patches preceded by mild erythema and scaling, is more often a manifestation of atopic dermatitis and is observed above all between the ages of 3 and 16 years in both sexes on the trunk, cheeks, and arms. Juvenile plantar dermatosis has been described almost exclusively in children who actively practice sports: the plantar surface of the forefoot appears smooth and shiny, with ragades at the flexor folds of the toes. Pompholyx, that is a recurrent eruption of vesicles on non erythematous skin of the palms and soles, may occur at any age, although it is more common in young adults; the cronicity of the disease can favour the occurrence of contact allergy. Seborrhoeic dermatitis, that is characterized by a peculiar clinical picture and sites (scalp, face, and upper trunk), has a incidence of 3-5% in the general population.