- Skin biopsy: Examination of skin tissue may help to explain how IL-2 causes changes in the skin. Biopsies will be obtained from areas of the skin that have been affected by IL-2 as well as from normal, unaffected areas for comparison. Patients with Kaposi sarcoma will also have biopsies of normal skin to allow comparison with IL-2-induced changes in the Kaposi sarcoma lesions. The areas to be biopsied will be numbed with local anesthetic and a 2-mm (1/10th-inch) piece of skin will be biopsied from each site.