Psoriasis mostly develops acutely, initially as an inflammatory red papule, about the size of a corn to a green bean, and later may gradually expand or fuse into a brownish-red plaque with clear borders, surrounded by an inflammatory red halo, with a distinct basal infiltrate and covered with multiple layers of dry, silvery-white scales. Gently scrape away the surface scales, gradually reveal a layer of light red shiny translucent film, this is the epidermal spiny cell layer, called the film phenomenon, and then scrape away the film, that is, to reach the top of the dermal papillary layer. The capillaries here are scraped and bleeding points appear, called punctate bleeding phenomenon. White scales, shiny film and punctate hemorrhage are the clinical features of initial psoriasis.