Extraordinary Case ReportCutaneous Malignant Melanoma With Rhabdoid Morphology and Smooth Muscle Differentiation: A Challenging Histopathologic DiagnosisPrieto-Torres, Lucía MD*; Alegría-Landa, Victoria MD†; Llanos, Concepción MD‡; Córdoba, Alicia MD‡; Kutzner, Heinz MD§; Requena, Luis MD†Author Information *Department of Dermatology, Hospital Clínico Universitario Lozano Blesa, Zaragoza, Spain; †Department of Dermatology, Fundación Jiménez Díaz, Universidad Autónoma, Madrid, Spain; ‡Department of Pathology, Complejo Hospitalario de Navarra, Pamplona, Spain; and §Dermathopathologie Friedrichshafen, Friedrichshafen, Germany. Reprints: Luis Requena, MD, Department of Dermatology, Fundación Jiménez Díaz, Avda, Reyes Católicos 2, Madrid 28040, Spain (e-mail: [email protected]). The authors declare no conflicts of interest. The American Journal of Dermatopathology: May 2017 - Volume 39 - Issue 5 - p 397-403 doi: 10.1097/DAD.0000000000000792 Buy Metrics Abstract Divergent differentiation or metaplastic change is a rare feature exhibited occasionally in malignant melanoma (MM), which is characterized by the development of morphologically, immunochemically, and/or ultrastructurally nonmelanocytic cells within the tumor. Smooth muscle differentiation in MM is an exceedingly rare phenomenon reported only in a few cases in the literature. We report the case of a 69-year-old woman who presented with a pure dermal amelanotic MM with smooth muscle cell differentiation and an area of rhabdoid morphology, which made the accurate histopathologic diagnostic of MM challenging. Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.