Malignant bone-forming tumors that arise from the surfaces of long bones
are far less common than those that arise from within bone. These surface
osteosarcomas are clinically and radiographically similar, yet
histologically they are quite distinct. In reviewing the literature, we
classified the tumors according to three subgroups: parosteal
(juxtacortical) osteosarcoma, periosteal osteosarcoma, and high-grade
surface osteosarcoma. We also studied the clinical, radiographic, and
histological findings in eighty patients who had been treated for an
osteosarcoma over a forty-four-year period. Adequate follow-up data existed
for forty-eight of the eighty patients. The duration of follow-up ranged
from two to fifteen years after the initial operation (amputation or
resection). Patients who had a parosteal osteosarcoma had the best
prognosis; those who had a periosteal osteosarcoma, the next best; and
those who had a high-grade surface osteosarcoma, the poorest. Because of
these widely varying prognoses, the lesions require different
treatment.