Whether or not you have psoriasis can be judged based on clinical manifestations and special examinations, specifically: 1. From the clinical manifestations, a preliminary judgment can be made based on whether or not the rash of psoriasis is recurrent and the location of the episodes of atypical psoriasis; 2. From the special examinations, if the Auspitz sign (scraping off the scales on the surface of the lesion and a thin film appears, followed by scraping the film to reveal small bleeding spots) is positive, there is a high probability of having psoriasis; to further confirm the diagnosis, pathological examination is required.