In a restrospective macroscopic and microscopic study of twenty-six
macrosections of skeletally immature individuals with metaphyseal
osteosarcoma, we determined the incidence, extent, and mode of tumor
extension into the epiphysis. The physis appeared to have a tendency to act
as a barrier to tumor spread, but did not restrain the tumor tissue in most
cases. Epiphyseal extension of the tumor tissue was massive in more than
half of the cases, with tumor tissue abutting against the articular
cartilage, and in one instance perforating it. Some tumors had a sizable
extra-osseous component that extended around the physis beneath the
perichondral ring and capsular structures into the ossific nucleus. These
findings have important implications when limited surgery is performed for
appendicular osteosarcoma.