Two Skin Diseases

Eczema

Eczema is a clinical term that embraces a number of pathologically different conditions. All are characterized by redness, papulovesicular, weeping, crusting lesions at the onset which, if they persist, become raised, scaling plaques. The classifications include contact dermatitis, a-topic or allergic dermatitis, drug related dermatitis and primary irritant dermatitis. These invoke the immune system to varying degrees and the pathways and processes of inflammation.

The initiators may be internal or external and clinical evaluation must identify these. However the lesions themselves have great similarity in their broad underlying pathophysiology if not distribution. Antigens trigger the response from the immune / inflammatory systems. Local treatment must focus on these similarities.

Psoriasis

Psoriasis is a common inflammatory dermatosis. Research indicates that psoriasis is a systemic disorder of the immune system which provokes activation and disordered growth of certain skin cells.   While psoriasis can take many forms, it is fundamentally a hyperproliferation of skin cell production at the basal membrane. There is change to the layers of the epidermis with diminished differentiation. As well as inflammation there is scaling with multiple, minute bleeding points. A key insight into psoriasis is that it is a disorder of cell signalling mediated by a dysfunctional immune  stimulus.

The Stratum Corneum barrier may regulate epidermal proliferation. However, epidermal DNA synthesis increases when the barrier function of the Stratum Corneum is decreased through exposure to organic solvents, and this proliferation could be a homeostatic response  . In ichthyosis and psoriasis there is altered barrier function and keratinocyte hyperproliferation. Altered barrier function may be the primary event that triggers epidermal hyperplasia and subsequent inflammatory features in such disorders.