CS-01 GIANT CELL TUMOR IN THE SKULL BASE BONE TREATED WITH ANTI-RANKL INHIBITOR

Giant cell tumor of bone is a rare and osteolytic neoplasm that that usually affecting the epiphyses in long bones of the extremities. They seldom occur in the skull, preferentially affecting the sphenoid and temporal bones. Most pathologically benign, and total removal by surgery was regarded as the first treatment, however, it was very difficult in skull lesion. In 2014 the molecular targeting drug anti-RANKL inhibitor was approved in Japan. We report a case in which an anti-RANKL inhibitor was administered to a skull base bone giant cell tumor that was difficult to remove completely. A 56-year-old man with a sudden right neck pain followed by dysphoria and dysphagia was referred to our hospital. Computed tomography showed 4.4 x 2.0 cm osteolytic lesion involving the right occipital bone and occipital condyle. Magnetic resonance imaging demonstrated an extensive soft-tissue mass occupying. Surgical biopsy was performed and the pathological diagnosis was giant cell tumor. Patient received the anti-RANKL inhibitor (Denosumab®). After 4 weeks, ossification was observed, and neurological symptoms were improved after 12 weeks. Patient has been on good course for 5 years without recurrence and is still following-up.