Brief ReportDouble CD4/CD8-Positive, Nonpoikilodermic Mycosis Fungoides Expressing CD56 in a Young ManSantonja, Carlos MD, PhD*; Sánchez-García, Francisco-Javier MD†; Rodríguez-Rodríguez, Rosa-Nieves MD, PhD‡; Manso, Rebeca PhD*; Requena, Luis MD, PhD§; Gil-Mateo, María del Pino MD¶; Rodríguez-Pinilla, Socorro-María MD, PhD* Author Information *PathologyDepartment, Hospital Universitario Fundación Jiménez Díaz, Madrid, Spain; †PathologyDepartment, Hospital General de Villalba, Madrid, Spain; ‡PathologyDepartment, Hospital Universitario de Canarias, Tenerife, Canarias, Spain; §DermatologyDepartment, Hospital Universitario Fundación Jiménez Diaz, Madrid, Spain; and ¶Dermatology Department, Hospital General de la Palma, Canarias, Spain. Correspondence: Socorro-María Rodríguez-Pinilla, MD, PhD, Hospital Universitario Fundación Jiménez Díaz, Pathology Department, Avda. Reyes Católicos, 2, Madrid 28040, Spain (e-mail: [email protected]). This work was supported by grants from the Instituto de Salud Carlos III (ISCIII) of the Spanish Ministry of Economy and Competence (MINECO, RTICC ISCIII, and CIBERONC) (SAF2013-47416-R, RD06/0020/0107, RD012/0036/0060, and Plan Nacional I+D+I: PI17/2172, PI16/01294, and PIE15/0081), AECC, and the Madrid Autonomous Community. The authors declare no conflicts of interest. Informed written consent has been obtained. Studies have been performed according to the Declaration of Helsinki. The procedures have been approved by a local ethics committee. Date November 8, 2018; Approval Number: PICO75-18_FJD; CEIm-FJD. The American Journal of Dermatopathology 44(12):p 936-939, December 2022. | DOI: 10.1097/DAD.0000000000002259 Buy Metrics Abstract We report a case of mycosis fungoides (MF) in an 18-year-old man whose neoplastic T cells expressed CD4, CD8, and CD56, with no evidence of TCR-delta or Epstein–Barr virus (EBER) expression. Clinically, neither hypopigmentation nor hyperpigmentation nor poikilodermatous skin lesions were present, and the lesions subsided with oral corticoids and retinoids and environmental solar ultraviolet exposure. Our case represents the oldest patient reported so far with nonpoikilodermatous, CD8/CD56 MF and adds to the phenotypic diversity of MF in the pediatric population. This distinct phenotype does not seem to be linked to a more aggressive course than the classic CD-4 positive one. Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.