Metastases detected at the time of diagnosis of primary pediatric extremity osteosarcoma at diagnosis: imaging features.

BACKGROUND: The authors performed a retrospective study to estimate the incidence rate of metastatic disease at the time of diagnosis of extremity osteosarcoma (OS), to characterize its pattern of presentation, and to identify factors predictive of survival within a cohort of patients with pulmonary metastatic disease at diagnosis.

METHODS: From the institutional solid tumor database, the authors identified all patients diagnosed with extremity OS since CT became available at the study institution (1977). The authors recorded patient demographics, the site of primary disease, the histologic subtype of OS, and the presence of metastases at diagnosis. In those patients with pulmonary metastases at diagnosis, the presence of calcifications, the primary tumor volume, the number of pulmonary lobes with disease, and the number of pulmonary nodules were recorded.

RESULTS: Of an evaluable population of 215 patients, 32 (15%) had bone or pulmonary metastases at diagnosis, of whom original imaging from 28 patients was available for review. Osteoblastic histology correlated with lung metastases at diagnosis (P = 0.049). One of the 32 patients had a solitary bone metastasis without lung metastases. Four of 28 patients (14%) with original imaging available had calcifications within the pulmonary nodules. Both the number of nodules and the number of lobes involved were found to be significant predictors of survival (P = 0.0009 and P = 0. 04, respectively); multiple nodules were bilateral in 61% of patients.

CONCLUSIONS: The rate of incidence of computed tomography detected pulmonary metastases was found to be 14% (31 of 215 patients) at diagnosis and 0.5% (1 of 215 patients) for bone metastases in patients with primary extremity OS. Pulmonary metastases usually are multiple and bilateral and infrequently calcify. The number of nodules and lobes involved are predictors of patient survival.