Most types of psoriasis result from stress, skin injuries, medications, infections, diet, weather change etc. Psoriasis can be classified into seven types- Plague, Guttate, Inverse, Pustular, Erythrodermic, Nail and Psoriatic Arthritis. All seven types can be treated with different medications and procedures. Talking about Psoriatic Arthritis, it is a condition when you have both psoriasis and arthritis. Researchers state in 70% of cases, people have psoriasis for around 10 years before getting psoriatic arthritis. And also about 90% of people suffering from it have nail changes. It is very much important to get plaque psoriasis treatment,skin psoriasis treatment or severe psoriasis treatment by a good dermatologist.