Psoriasis can be mild, moderate or severe. Your treatment options may depend on how severe your psoriasis is. Severity is based on how much of your body is affected by psoriasis. The entire hand (the palm, fingers and thumb) is equal to about 1 percent of your body surface area.
However, the severity of psoriasis is also measured by how psoriasis affects a person's quality of life. For example, psoriasis can have a serious impact on one's daily activities even if it involves a small area, such as the palms of the hands or soles of the feet.