*Department of Dermatology, Feinberg School of Medicine, Northwestern University, Chicago, IL

†Department of Pathology, Emory University School of Medicine, Atlanta, GA

¶Department of Pathology, Dermatopathology Service, Memorial Sloan Kettering Cancer Center, New York City, NY

∥Department of Pathology, Yale School of Medicine, New Haven, CT

**Department of Dermatopathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA

††Department of Pathology and Laboratory Medicine, Division of Anatomic Pathology, Hospital of the University of Pennsylvania

§§§§Departments of Pathology and Dermatology, University of Pennsylvania, Philadelphia, PA

‡‡Department of Anatomic Pathology, Cleveland Clinic, Cleveland, OH

∥∥Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX

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

§§§Departments of Pathology and Cutaneous Oncology, Moffitt Cancer Center, Tampa, FL

¶¶¶Departments of Pathology and Dermatology, Emory University School of Medicine, Atlanta, GA

††††Department of Medicine, Section of Dermatology, University of Chicago, Chicago, IL

∥∥∥∥Departments of Dermatology and Pathology, University of California, San Francisco, San Francisco, CA

####Dermatopathology Consultations LLC, Lahey Clinic and Tufts Medical School, Boston, MA

‡Department of Translational Research, Institut Curie, Paris Sciences and Lettres Research University, and UFR of Medicine, University of Paris Cité, Paris

#Department of Biopathology, Centre Leon Bernard, Lyon, France

§Department of Pathology, Division Laboratories, Pharmacy and Biomedical Genetics University Medical Center Utrecht, The Netherlands

§§Department of Pathology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil

##Tissue Pathology and Diagnostic Oncology, Royal Prince Alfred Hospital, and NSW Health Pathology, Sydney, NSW, Australia

***Faculty of Medicine and Health

†††Melanoma Institute Australia

****Charles Perkins Centre, The University of Sydney, Sydney, NSW, Australia

‡‡‡Department of Health Sciences, Section of Anatomic Pathology, University of Florence, Florence, Italy

∥∥∥Institute for Pathology and Molecular Pathology, University Hospital Zurich, Zurich, Switzerland

###Department of Pathology, McGill University, Montreal, QC

‡‡‡‡Department of Dermatopathology, University of Toronto, Toronto, ON, Canada

¶¶¶¶Department of Dermatology, Chonnam National University Medical School, Gwangju, Korea

A.C. and Ms N.S. contributed equally to this manuscript.

Supported by the IDP Foundation and with the support of the Greg and Anna Brown Foundation.

This study was approved by our Institutional Review Board (IRB) (STU00001127). Given the retrospective chart review design, a waiver of HIPPA authorization was granted for research purposes, and informed consent was not required for this study.

Conflicts of Interest and Source of Funding: P.G. has served as a consultant for Castle Biosciences and has received an honorarium for this, he has also received royalties for textbooks from Elsevier. For the remaining authors, none were declared.

Correspondence: Pedram Gerami, MD, Department of Dermatology, Northwestern University, 676 N. St. Clair St., Suite 1765, Chicago, IL 60611 (e-mail: [email protected]).