Psoriasis is a chronic autoimmune disease where the immune system of psoriasis patients mistakenly attacks normal, healthy skin cells, leading to excessive growth, accumulation, scaling, and redness of skin cells. This ultimately results in the formation of typical psoriasis plaques (they can appear anywhere but are most commonly found on the scalp, elbows, knees, and lower back).
Psoriasis can also manifest as specific nail changes (nail pitting, thickening and deformation, changes in nail bed color, oil drop-like spots, nail detachment, and thickening of the skin under the nails).