Giant cell rich osteosarcoma, a challenging histopathological diagnosis : A case report

Abstract

Giant cell-rich osteosarcoma is a rare histologic subtype of conventional osteosarcoma, accounting for 1-3% of conventional osteosarcoma. The microscopic features show numerous non-neoplastic osteoclast-like giant cells (no nuclear atypia) and pleomorphic malignant giant cells with highly pleomorphic mononuclear cells and a variable amount of osteoid matrix formation. Giant cell-rich osteosarcoma is difficult to histopathologically differentiate from giant cell tumors of bone and malignant in giant cell tumors of bone. This article reports a 41 years old man with a painful mass on the right knee. The radiologic findings show osteolytic lesion at the epiphysis and metaphysis area of the distal femur. The pathological diagnosis of the biopsy specimen was a giant cell tumor of bone, but the pathological diagnosis after wide resection of the tumor was malignant in giant cell tumor. After a histomorphologic review of the wide resection specimen, the pathological diagnosis was giant cell-rich osteosarcoma.
Keyword : Giant cell-rich osteosarcoma, osteoclast-like giant cell, osteoid matrix