“…[4][5][6][7] On the other hand, other primary brain tumors that have been reported to involve the skin of the scalp, whether from surgical implantation, direct extracranial extension, or metastasis, include astrocytoma (particularly anaplastic astrocytoma), anaplastic ependymoma, glioblastoma multiforme, and meningioma. 19,[46][47][48][49][50][51][52][53][54][55][56] Cerebrospinal fluid may serve as a means for AO to metastasize to other sites in the central nervous system, and direct tumor extension along the leptomeninges can give rise to leptomeningeal oligodendrogliomatosis. 1,15,19,20,22,25,33,44 Craniotomy may provide direct access for the tumor to grow extracranially and may disrupt the blood-brain barrier, so that tumor cells can access extracranial blood vessels and metastasize thereby.…”