Brief ReportMesenchymal PLAG1 Tumor With PCMTD1-PLAG1 Fusion in an Infant: A New Type of “Plagoma”Tomás-Velázquez, Alejandra MD*; Surrey, Lea F. MD†; Miele, Evelina MD, PhD‡; Li, Marilyn M. MD†; Alaggio, Rita MD§; Goitz, Robert J. MD¶; Reyes-Múgica, Miguel MD║; Salgado, Cláudia Maria MD, PhD║Author Information *Department of Dermatology, University Clinic of Navarra, School of Medicine, University of Navarra, Pamplona, Spain; †Department of Pathology and Laboratory Medicine, Children’s Hospital of Philadelphia, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA; ‡Department of Pediatric Hematology/Oncology, IRCCS Bambino Gesù Children's Hospital, Roma, Italy; §Department of Pathology, Ospedale Bambino Gesù, Roma, Italy; ¶Orthopedic Division, University of Pittsburgh Medical Center, Pittsburgh, PA; and ║Department of Pathology, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA. Correspondence: Alejandra Tomás-Velázquez, MD, Department of Dermatology, University Clinic of Navarra, School of Medicine University of Navarra Avda. Pio XII, 36, 31008 Pamplona, Spain (e-mail: [email protected]). The authors declare no conflicts of interest. The American Journal of Dermatopathology: January 2022 - Volume 44 - Issue 1 - p 54-57 doi: 10.1097/DAD.0000000000001978 Buy Metrics Abstract In the past decade, there have been major advances in knowledge related to mesenchymal tumors, and new genetic alterations are being delineated. We report a mesenchymal spindle cell neoplasm harboring a novel gene fusion in an infant. Histopathologically, the neoplasm shared some features with sclerosing perineurioma, but immunohistochemically, EMA was negative, whereas GLUT1, NK1-C3, and BCOR were positive. Next-generation sequencing revealed a PCMTD1–pleomorphic adenoma gene 1 (PLAG1) fusion. PLAG1 contributes to the expression of a variety of genes implicated in regulating cell proliferation, and PCMTD1 has been related to the development of certain carcinomas. Recently, other soft tissue tumors in young children associated with PLAG1 fusion variants have been reported. Perhaps, mesenchymal neoplasms presenting PLAG1 fusions with different genes would confirm a specific group (PLAG mesenchymal tumours or “plagomas”) in the near future. Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.