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Why can chronic skin disease cause scaling and thickening of the epidermis?

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skin rash caused by Lyme disease — skin disease Visible alterations in the texture of the skin, such as rashes and hives, can be indicative of serious disease. For example, one of the first signs of Lyme disease is a circular rash in a bull's-eye pattern on the skin.

Chronic skin diseases often cause scaling and thickening of the epidermis due to an overproduction of cells or a disorganization of their differentiation. In conditions like psoriasis, the balance between cell production and loss is altered, resulting in a greatly increased rate of cell division in the malpighian layer.12

In chronic forms of eczema or dermatitis, the epidermis undergoes thickening and marked hyperkeratosis—an overproduction of keratin by epidermal cells. These changes lead to lichenification, where the skin's surface markings become exaggerated and rough.13

Furthermore, the impairment of the skin's barrier function in these chronic states leads to water loss and desiccation of the horny layer, which subsequently causes cracking and increased scaling. While inflammation is a common driver of these morphological changes, the primary mechanism for the observed thickening and scaling remains the accelerated or disordered proliferation of epidermal cells.321