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How does psoriasis cause the epidermis to become abnormally thick?

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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.

Psoriasis causes the epidermis to become abnormally thick through a process of accelerated cell proliferation triggered by an immune-mediated response. In this condition, immune cells known as T cells attack healthy skin cells, which disrupts the normal balance between cell production and loss.123

This attack forces keratinocytes to reproduce much more rapidly than normal, shortening their life span from the typical 20 to 28 days to approximately 3 to 5 days. The resulting thickening of the epidermis occurs because the rate of cell production in the malpighian layer is significantly increased, causing cells to move through the epidermis at a much faster pace. While the exact trigger for this increased proliferation—whether due to an excess of growth-promoting factors or a deficiency in growth inhibitors—remains a subject of research, it is generally understood that the process involves both the recruitment of previously noncycling cells into active division and a speeding up of the cell cycle.123