Answer and Discussion of Quiz Set: W-001

2.    Which of the brain tumors has the highest tendency to metastasize to bone?

A.  Pleomorphic xanthoastrocytoma

B.  Medulloblastoma

C.  Glioblastoma

D.  Pilocytic astrocytoma

E.  Ependymoma arising within the brain and spinal cord.

Answer and Discussion: The answer is (B). Primary malignant brain tumors do not usually metastasize. However, the most frequent site of metastsis for medulloblastoma is bone. Pilocytic astrocytoma and pleomorphic xanthoastroma do not have metastatic potential. Gliosarcoma do not usually metastasize but the most common sites are lymph node and lung. The metastatic potential of ependymoma arising within the brain and spinal cord has very low metastatic potential similar to other primary malignant brain tumors. However, ependymoma can arise in extradural locations. Extradural ependymomas are extremely rare. These tumors have been reported to arise in the extradural spinal canal in association with the dural part of the filum terminale, the sacral bone, the pelvic cavity anterior to the sacrum, and the subcutaneous tissue overlying the sacrum. Extradural ependymomas behave like a carcinoma are much more likely to metastasize through lymphatics, lungs, bones, and liver. In contrast, extradural ependymas are unlikely to disseminate through the CSF like their dural counterparts.

Reference:

Liwnicz BH, Rubinstein LJ. The pathways of extraneural spread in metastasizing gliomas: a report of three cases and critical review of the literature. Hum Pathol. 1979 Jul;10(4):453-67.