How do nails become psoriatic?

Psoriasis: At the time that psoriatic (pathological) change involves nail "root"(matrix), the nails would be psoriatic when they form and grow out.

Psoriasis: Pitting of the nails is a symptom of psoriasis. Nail pitting is small depressions in the nails. Nail pitting is most common in people who have psoriasis — a condition characterized by scaly patches on the skin. Nail pitting can also be related to connective tissue disorders, such as reiter's syndrome, and alopecia areata — an autoimmune disease that causes hair loss.