Am J Surg Pathol 2016 Jan;40(1):72-80
*Department of Pathology and Laboratory Medicine, Hospital of the University of Pennsylvania, Philadelphia, PA †Department of Pathology, Miller School of Medicine, Jackson Memorial Hospital, University of Miami, Miami, FL ‡Department of Radiology §Department of Medicine, Division of Oncology ∥Department of Orthopaedics ¶Department of Pathology, Massachusetts General Hospital, Boston, MA.
Giant cell tumor (GCT) of bone is a locally aggressive benign neoplasm characterized by an abundance of osteoclastic giant cells that are induced by the neoplastic mononuclear cells; the latter express high levels of receptor activator of nuclear factor κ-B ligand (RANKL). Denosumab, a RANKL inhibitor, which is clinically used to treat GCT, leads to a marked alteration in the histologic appearance of the tumor with giant cell depletion and new bone deposition, leading to substantial histologic overlap with other primary tumors of bone. Most significantly, denosumab-treated GCT (tGCT) with abundant bone deposition may mimic de novo osteosarcoma, or GCT that has undergone malignant transformation. Read More