Osteoblastic metastases from astrocytomas: a report of two cases.

The spread of primary central nervous system (CNS) neoplasms beyond the confines of the neuraxis is a relatively uncommon observation. Extraneural metastases involving bone are quite rare, and have been observed almost exclusively in cases of medulloblastoma, high-grade (III-IV) astrocytoma, and glioblastoma multiforme. To date there has been only one case reported of bone metastasis from a "well-differentiated" astrocytoma. We now report two cases of astrocytoma in children with diffuse osteoblastic metastases and a fulminant clinical course. These cases demonstrate that due to the potential morphologic heterogeneity of these neoplasms, an initial biopsy diagnosis of low-grade astrocytoma does not always imply a benign clinical course.