Periosteal chondroma and periosteal chondrosarcoma.

A clinicopathologic study of 46 patients with periosteal chondroma and 14 patients with periosteal chondrosarcoma revealed that periosteal chondroma tended to affect younger patients and that the lesion was usually smaller. Radiographically, the typical periosteal chondroma was a small, well-marginated tumor on the outer surface of a long bone. Erosion of the cortical surface and marginal buttresses were usually present. Periosteal chondrosarcoma had a more aggressive appearance and was seen as a large mass located superficially on the cortex; the margins of the mass were more irregular than those of chondroma. Histologically, periosteal chondroma frequently showed hypercellularity, plump nuclei, and binucleation. Thus, the differentiation of chondroma from chondrosarcoma is difficult and is based mainly on evidence of invasion. The prognosis in periosteal chondroma is good: only one patient had a local recurrence, none of the tumors underwent malignant change, and excision seems to be curative. However, the prognosis in periosteal chondrosarcoma is not as good: two patients died of metastasis to the lungs after local excision and two patients had recurrences after local resection. Periosteal chondrosarcoma should be treated more aggressively than periosteal chondroma.