Osteosarcoma of the thoracic spine developed in a 15-year-old Japanese
boy, After his first admission with paralysis, multiple skeletal meta
stases were demonstrated in the absence of pulmonary metastasis. This
rare condition may possibly be considered as a unicentric osteosarcoma
with bone metastases, since there were no precursor lesions or histor
y of exposure to radioactive materials or chemical agents. These multi
ple lesions may be an example of so-called ''organ-specific metastasis
,'' although this ''nonstochastic'' process is rare.