Sarcoma arising in metastatic carcinoma in the brain. A second instance.

A second instance in which a carcinoma metastatic to the brain has induced the formation of a sarcoma in the associated cerebral blood vessels, is reported. This is analogous to the more common gliosarcoma, a tumor in which a primary glioma, most often anaplastic astrocytoma (glioblastoma multiforme), has induced the formation of a similar sarcoma, with both neoplastic tissues in the same tumor mass. The formation of the sarcoma is attributed to a neoplastic change in the markedly hyperplastic endothelial cells of the cerebral blood vessels that are very commonly found with anaplastic astrocytomas and are often found in relation to metastatic carcinoma. The progression of hyperplasia to neoplasia has long been considered of oncogenetic significance, and in this specific circumstance, appears to be due to some factor or substance which passes from the carcinoma cells to the cerebral vessels.