Résumé
Giant cell tumor [GCT] is a primary benign neoplasm of bone. It accounts for 5% of all skeletal tumors. It usually originate from long bones. We report three cases of GCT arising from rare locations. Two lesions were seen involving the tarsal bones of foot including the talus and calcaneum. The third case originated from an extremely rare site i.e. sternum. Tumor from calcaneum presented with pain and swelling in right heel. Physical examination revealed swelling of tendoachilles and calcaneum. On plain radiography there was expansile lytic lesion of calcaneum. Contrast enhanced MRI demonstrated expansile, erosive, locally aggresive mass lesion of calcaneus with exophytic extension. The mass demonstrated iso-intensity on T1WI, heterogenous hyperintensity was seen on T2WI with non homogenous enhancement on post contrast examination. The tumor was resected and histological features were consistent with Giant cell tumor. The other case involving the talus presented with pain in left ankle joint. Plain radiograph and MRI scan showed a lytic, solid cum cystic mass lesion involving the body ,neck and tail of the talus bone. Enbloc resection with total talectomy and arthrodesis with cementing was done. The third case involved sternum which is an extremely rare location for GCT. This was a 48 years old female who presented with a history of pain in midline upper chest and cough. On examination a firm mass was present on anterior chest wall in the region of manubrium sterni. On computed tomography [C.T] an expansile lytic mass was seen in the sternum. Fine needle aspiration cytology was done and histopathology was consistent with Malignant Giant Cell Tumor