Hi, Psoriasis is a recalcitrant,autoimmune and chronic scaly dermatosis. There is no exact cause. It may be hereditary in some cases. There may be precipitateing factors..like tension,anxiety,dry weather,drugs,injuries..etc. Remember, psoriasis is a controllable disease, treatment is taken to reduce the severity of the lesions and to prevent the relapses. However in some patients, the disease may not recur after frequent relapses. Our aim should be to reduce disease period and to increase healthy period. You may discontinue treatment when there is zero lesion. But, restart treatment ,when there is small lesion anywhere. Positive approach and regular treatment may improve you life. Methotraxate in pulses is root treatment of psoriasis. So, consult dermatologist and had have treatment. And never become sad. Just be positive and live with minimum disease. I hpe you got my answer. Thanks. Dr. Ilyas Patel MD