1 Department of Dermatology, Langeland Hospital, Zoetermeer, The Netherlands; Department of Dermatology, Ghent University Hospital, Ghent, Belgium.
2 Department of Dermatology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
3 Harvard Medical School, Boston, Massachusetts, USA.
4 Countway Library, Harvard University, Boston, Massachusetts, USA.
5 Department of Dermatology, Keck School of Medicine of USC, University of Southern California, Los Angeles, California, USA.
6 National Psoriasis Foundation, Portland, Oregon, USA.
7 Department of Dermatology, University of California San Francisco, California, USA.
8 Department of Dermatology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA; Division of Rheumatology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA. Electronic address: jfmerola@bwh.harvard.edu.