Epiphyseal extension of metaphyseal osteosarcoma in skeletally immature individuals.

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.