Assuntos
Neoplasias Ósseas/diagnóstico por imagem , Osteossarcoma Justacortical/diagnóstico por imagem , Medronato de Tecnécio Tc 99m , Tíbia/diagnóstico por imagem , Adulto , Neoplasias Ósseas/diagnóstico , Neoplasias Ósseas/metabolismo , Diagnóstico Diferencial , Humanos , Ossificação Heterotópica/diagnóstico , Ossificação Heterotópica/diagnóstico por imagem , Ossificação Heterotópica/metabolismo , Osteossarcoma Justacortical/diagnóstico , Osteossarcoma Justacortical/metabolismo , Palpação , Radiografia , Cintilografia , Compostos Radiofarmacêuticos/farmacocinética , Medronato de Tecnécio Tc 99m/farmacocinética , Tíbia/metabolismo , Tíbia/patologiaRESUMO
BACKGROUND: Parosteal osteosarcoma with dedifferentiation provides a useful model to study tumor progression from an indolent locally aggressive neoplasm to highly lethal metastasizing malignancy. Up-regulation of the proteolytic enzymes participating in stromal degradation is known to promote invasive growth and metastasis of several human and experimental tumors. METHODS: The expression patterns of urokinasase plasminogen activator (u-PA), its cell-surface receptor (u-PAR), and cathepsin B were analyzed by immunohistochemical techniques in 11 cases of parosteal osteosarcoma and in 4 cases of dedifferentiated parosteal osteosarcoma. RESULTS: Both enzymes and the receptor were coexpressed in most tumor cells of parosteal and dedifferentiated parosteal osteosarcoma. Their expression was strikingly enhanced in the dedifferentiated high-grade component of the tumors. Tumor cells involved in bone production (ie, those adjacent to tumor produced bone trabeculae) exhibited equally strong expression of u-PA, u-PAR, and cathepsin B, regardless of their histologic grade. Expression of u-PA, u-PAR, and cathepsin B was undetectable in the "normalized" cells embedded in the well-developed tumor bone trabeculae. CONCLUSION: These data indicate that u-PA and its interacting molecules, such as u-PAR and cathepsin B, may have some contributory effects on the metastatic potential of tumor cells in dedifferentiated parosteal osteosarcoma.