Psoriasis is a common, chronic skin disease, whose diagnosis is based mainly on clinical features but, in some cases, can be difficult. As the exact diagnosis of psoriasis and the differential diagnosis with other diseases are crucial for the therapeutic choice, several studies investigated the relevance of some genes and proteins as potential specific skin biomarkers. Despite a large number of reports, none of them has been tested in large studies and thus achieved regulatory approval and clinical application. Authors give an overview on the skin biomarkers (BMs) in psoriasis, distinguishing inflammatory and epidermal biomarkers, highlighting the most distinctive skin psoriasis BMs, that can help physicians and pathologists to recognize psoriasis among "psoriasiform dermatitis".