The diseases of white patches is characterized by localized loss of pigmentation of skin. it occurs when the cells (melanocytes) responsible for producing the pigment (melanin) for skin color are damaged . The exact cause of this condition is not known but it may arise from stress, positive family history or autoimmune condition in which immune system of body destroys its own cells and tissues. Psoriasis is a common skin condition that speeds up the life cycle of skin cells. it causes cells from scales and red patches that are itchy and sometimes painful. Psoriasis is a chronic disease that often comes and goes. it may occur anywhere on the body but typically occurs on the elbows, knees, scalp, back, face palms and feet.