Original StudyDesmoplastic Melanomas Mimicking NeurofibromasGerami, Pedram MD*,†; Kim, Daniel BS*; Zhang, Bin MS*; Compres, Elsy V. BA*; Khan, Ayesha U. MBA*; Yazdan, Pedram MD*; Guitart, Joan MD*; Busam, Klaus MD‡Author Information *Department of Dermatology, Feinberg School of Medicine, Northwestern University, Chicago, IL; †Robert H. Lurie Cancer Center, Feinberg School of Medicine, Northwestern University, Chicago, IL; and ‡Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, NY. Correspondence: Pedram Gerami, MD, Professor of Dermatology and Pathology, Northwestern University, Department of Dermatology, 676 N. St Clair St., Suite 1765 Chicago, IL 60611 (e-mail: [email protected]). P. Gerami has served as a consultant for Myriad Genomics, DermTech Int., Merck and Castle Biosciences and has received honoraria for this. This work is original and has not been previously published. The remaining authors have no conflict of interest to disclose. The American Journal of Dermatopathology: December 2020 - Volume 42 - Issue 12 - p 916-922 doi: 10.1097/DAD.0000000000001754 Buy Metrics Abstract Desmoplastic melanoma can be difficult to diagnose and on average have a significantly higher T stage at the time of diagnosis compared with conventional melanomas. Histologically, these tumors typically consist of spindle cells in a fibrous matrix. The spindle cells may display fibroblast and/or Schwann cell–like features. In this study, we describe the features of 12 cases of desmoplastic melanoma closely simulating neurofibroma. Although the spindle cells in these tumors may be indistinguishable from those of neurofibroma, features such as prominent fibroplasia (12/12), poor lateral circumscription (8/9), diffuse infiltration of subcutaneous tissue (7/9), and lymphoid aggregates (10/12) may be helpful clues to the diagnosis. No immunohistochemical markers were reliable in distinguishing neurofibroma-like desmoplastic melanomas from neurofibroma. Clinical follow-up was available in 8 cases, of which 4 were initially misdiagnosed as benign neoplasms and given no further re-excision. All 4 of these cases recurred; 2 of which showed transformation to a more aggressive phenotype. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.