*Department of Pathology

**Division of Hematology and Oncology

††Department of Dermatology, University of Virginia, Charlottesville, VA

†Department of Dermatology, Kempf und Pfaltz Histologische Diagnostik, University of Zurich, Zurich, Switzerland

‡Department of Dermatology, Northwestern University, Chicago, IL

§Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York City, NY

∥Department of Dermatology, University Medical Center Göttingen, Venereology and Allergology, Göttingen, Germany

¶Departments of Pathology and Dermatology, University of Michigan, Ann Arbor, MI

#Departments of Pathology and Dermatology, The University of Texas MD Anderson Cancer Center, Houston, TX

‡‡Department of Pathology, Fundacion Jimenez Diaz, Madrid, Spain

§§Department of Pathology, European Institute of Oncology IRCCS, Hematopathology Division, Milan

##Department of Pathology, University of Bologna

¶¶Department of Surgical and Medical Science, Bologna University, Bologna, Italy

∥∥Dermatology Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna

***Department of Pathology, University of British Columbia, Royal Jubilee Hospital, Victoria, Canada

†††Departments of Pathology and Dermatology, The Ohio State University, Columbus, OH

‡‡‡Mayo Clinic, Department of Laboratory Medicine and Pathology, Rochester, MN

§§§Department of Dermatology, Medical University of Graz, Graz, Austria

IRB approval was obtained from the University of Virginia.

This research was funded in part through the NIH/NCI Cancer Center Support Grant P30 CA008748.

Conflicts of Interest and Source of Funding: A.L.F. receives research funding from Seattle Genetics, is an inventor of technology for which Mayo Clinic holds an unlicensed patent, and has intellectual property licensed to Zeno Pharmaceuticals. A.A.G. is an investigator for StemLine Therapeutics, Innate Pharma, and Dren Bio. He is also consultant for Kyowa Kirin and BluePrints Medicine. For the remaining authors none were declared.

Correspondence: Alejandro A. Gru, MD, 622 West 168th St.VC-15-207, New York 10032, NY (e-mail: [email protected]).