RESUMO
UNLABELLED: Chondroblastic osteosarcoma accounts for about 25% of all cases of osteosarcoma, which is the most common primary malignancy of the skeleton. Currently, only a few cases of chondroblastic osteosarcoma have been reported to involve the bones of the foot. In this report, we describe the previously unreported occurrence of chondroblastic osteosarcoma involving the left tarsal cuboid in a 15-year-old male. Histologically, the tumor showed an unusually extensive osteoclastic giant cell reaction that initially led to an erroneous diagnosis of giant cell tumor of bone. Because treatment and prognosis are very different for chondroblastic osteosarcoma as compared to giant cell tumor of bone, it is important to make the distinction between these 2 different bone tumors. In this report, we wish to draw attention to occurrence of chondroblastic osteosarcoma in the small bones of the foot, and to the possibility of an extensive giant cell reaction making accurate diagnosis difficult. We also provide a comprehensive review of the literature related to chondroblastic osteosarcoma. LEVEL OF CLINICAL EVIDENCE: 4.