A common reason why skin lesions are often excised surgically is to fully remove a skin cancer. If certain cancers are not cut out they may spread to the surrounding skin and metastasise, or spread, to other parts of the body.
However, other treatments such as freezing the affected skin (Cryotherapy), be it malignant or just an unsightly wart, can be treated medically with liquid nitrogen, which freezes and destroys the affected skin cells. This method is less time-consuming and it's cosmetic results are usually very good.