1. Division of Dermatology, University of California, San Diego, La Jolla, CA 92093, USA.
2. Department of Medicine and Dermatology, University of California, San Francisco, San Francisco, CA 94142, USA.
3. Veterans Administration San Diego Healthcare System, San Diego, CA 92161, USA.
4. Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA.