(D) CT scan following five months of denosumab therapy demonstrating almost complete containment of the soft tissue mass by a boney rim (arrow). Open in a separate window Figure 2 Histopathology of the pre- and post-treatment tumor tissue specimen. arterial embolization and resection [13,14]. Complications associated with Glucagon receptor antagonists-1 curettage are related to an incomplete resectability of the lesion resulting in recurrence in at least 20% . Clinically , ABCs can be divided into inactive, active and aggressive lesions with aggressive tumors expanding rapidly, destroying surrounding tissue and having a high rate of local recurrences. New therapeutic options are needed for the management of this locally aggressive disease. Denosumab, a monoclonal antibody specifically binding RANK-ligand, inhibits bone resorption and, therefore, [16-18] is used in the treatment of osteoporosis, skeletal complications of metastatic disease, and more recently in the treatment of giant cell tumors of bone, with a high rate of clinical success . To date, we are aware of only one publication presenting the application of denosumab in two cases of spinal ABCs . Both patients (an 8-year old boy and an 11-year old boy) recovered significantly from pain and neurological symptoms. MRI follow-up after two to four months of denosumab therapy showed tumor regression in both patients. We report a case of a locally aggressive periosteal Glucagon receptor antagonists-1 ABC with a confirmed rearrangement of arising in the radius of a 21-year old woman with an impressive local response to denosumab treatment and a follow-up of four years. Case presentation A 21-year old right-handed woman presented with a variable swelling and shooting pain in her right proximal forearm in May of 2009. Clinical examination showed Glucagon receptor antagonists-1 a palpable swelling over the radial head mainly located over the biceps tendon and a supination deficiency. MRI revealed an extensive, deep seated, solid soft tissue tumor with contrast uptake, infiltration of the intra-osseous membranes, biceps tendon, contact with the neurovascular bundle, infiltration of the supinator muscle and deep extensor as well as deep flexor muscles (Figure? 1A, B). Computer tomography (CT)-guided core-needle biopsy was performed with a clinical suspicion of Ewing sarcoma. A low-grade, giant cell-containing lesion with focal metaplastic bone formation and infiltration of the skeletal muscle was diagnosed on histopathological examination (Figure? 2A). No necrosis, Rabbit polyclonal to Hsp90 atypia or pathologic mitotic activity was noted. The osteoclastic giant cells were numerous and contained up to over 50 nuclei. Open in a separate window Figure 1 Imaging of the patients right forearm tumor. (A) Initial magnetic resonance imaging (MRI) demonstrating extensive involvement of the soft tissue between the radius and ulna as well as the cortex of the radius by an exclusively solid tumor mass (arrows). (B) Pre-treatment computer tomography (CT) scan with a small area of a split and disrupted cortex of the radius (arrows). (C) MRI directly prior to denosumab therapy with a locally progressive, extensive soft tissue mass following local surgical therapy 18 months previously. Fluid-fluid levels may be seen at this point (arrow). (D) CT scan following five months of denosumab therapy demonstrating almost complete containment of the soft tissue mass by a boney rim (arrow). Open in a separate window Figure 2 Histopathology of the pre- and post-treatment tumor tissue specimen. (A) Pre-treatment biopsy sample showing giant cell containing soft tissue mass with extensive infiltration Glucagon receptor antagonists-1 of the skeletal muscle (H&E stain; original magnification 50). (B) Abundant lesional giant cells with numerous nuclei and mononuclear cells in the background (H&E stain; original magnification 100). Inset shows immunohistochemical expression.