The difference between psoriasis and parapsoriasis includes the causes and symptoms. 1. Causes: The causes of psoriasis are mainly related to genetic, environmental and immune abnormalities. The cause of psoriasis is still unclear, may be related to drug allergy, pathogen infection, autoimmune disease, chronic dermatitis and other factors. 2. Symptoms: The clinical manifestation of psoriasis is scaly plaque or erythema, after scraping off the scales, there will be a light red shiny film, and there is a bit of hemorrhage under the film, and some patients may have itching and pain. The clinical manifestations of parapsoriasis are erythema, papules, and thin scales that are not easy to scrape off, and there is no punctate hemorrhage after the scales are forcibly scraped off. If you want to know the difference between psoriasis and parapsoriasis, you can go to the dermatology department of regular hospitals for consultation.