Review ArticlesExtranodal Follicular Dendritic Cell Sarcoma—A Review: “What the Mind Does Not Know the Eye Does Not See”Kaur, Ramandeep MD; Mehta, Jay MD; Borges, Anita MD, FRCPathAuthor Information Centre for Oncopathology, Mumbai, Maharashtra, India The authors have no funding or conflicts of interest to disclose. Reprints: Jay Mehta, MD, Centre for Oncopathology, 3rd Floor, Rectifier House, 570, Naigaon Cross Road, Wadala, Mumbai 400031, Maharashtra, India (e-mail: [email protected]). All figures can be viewed online in color at www.anatomicpathology.com. Advances In Anatomic Pathology: January 2021 - Volume 28 - Issue 1 - p 21-29 doi: 10.1097/PAP.0000000000000281 Buy Metrics Abstract Follicular dendritic cell sarcoma (FDCS) is an intermediate-grade malignancy of follicular dendritic cells, which are derived from mesenchymal stem cells. Nodal FDCS is well-recognized. However, when it occurs at an extranodal site, it may not be recognized and is often misdiagnosed. These tumors exhibit a variable spindle to epithelioid cell morphology with a lymphocytic infiltrate and a distinct immunophenotype. The World Health Organization has classified this entity under tumors of hematopoietic and lymphoid tissue, that is, histiocytic and dendritic cell neoplasms. However, its occurrence at extranodal sites and its behavior and management more closely resemble that of a soft tissue tumor. Increased awareness about the existence of FDCS at extranodal sites may aid in the reduction of diagnostic errors. We wish to draw attention to this entity by reporting our experience of 54 cases of extranodal FDCS encountered over a period of 14 years and present a review of the literature of this underrecognized entity. We also describe the ontogeny and molecular pathogenesis of this uncommon lesion. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.