Astroblastomas are rare glial tumors usually found in the cerebral hemispheres of young adults and children.
They occur at all ages range from early childhood to 6th decade but are most commonly seen in children, adolescents, and young adults with a mean age between 10-30 years 2,5. A female predilection has been suggested in some reports 5.
Astroblastomas, along with choroid gliomas of the third ventricle and angiocentric gliomas, are grouped as other neuroepithelial tumors in the current (2016) version of the WHO classification of CNS tumors 5.
They have not yet been given a WHO grade, but do have a range of histological appearance and biological behavior ranging from relatively indolent (astroblastoma) to aggressive (anaplastic or malignant astroblastoma) 4,5.
They are well-demarcated masses with areas of cystic degeneration and necrosis giving it a bubbly appearance. Hemorrhage and adjacent brain infiltration are rare.
Astroblastomas have elongated glial cells with abundant eosinophilic cytoplasm and a broad, or “stout”, GFAP positive process extending radially towards a central blood vessel, forming "astroblastic pseudorosettes", reminiscent to the perivascular pseudorosettes of ependymomas, which are a characteristic feature of this tumor. The central vessel tends to be hyalinized.
Although no agreed-upon criteria have been accepted, anaplastic/malignant histological features include 5:
- increased mitotic activity (>5 mitoses per 10 high-powered fields)
- high cellularity
- anaplastic nuclear features
- microvascular proliferation
- palisading necrosis
- usually Ki-67 >10%
Astroblastomas are usually fairly sizable, peripherally located, supratentorial lobulated solid cystic masses with little if any associated vasogenic edema 1-5. Multiple cysts are common and can give it a bubbly appearance. Calcification is very common and seen in 85% of cases, and usually in a punctate pattern.
Reported signal characteristics include
- T1: iso- to hypointense
- T2/FLAIR: heterogeneously hyperintense
- T1 C+ (Gd): heterogeneous enhancement
Treatment and prognosis
Surgical resection is the treatment of choice with adjuvant radiation therapy and chemotherapy reserved for high-grade lesions. Recurrence after complete surgical resection of low-grade tumors is uncommon 4.
Possible imaging differential considerations include:
- 1. Ganapathy S, Kleiner LI, Mirkin DL et-al. Unusual manifestations of astroblastoma: a radiologic-pathologic analysis. Pediatr Radiol. 2009;39 (2): 168-71. doi:10.1007/s00247-008-1038-z - Pubmed citation
- 2. Port JD, Brat DJ, Burger PC et-al. Astroblastoma: radiologic-pathologic correlation and distinction from ependymoma. AJNR Am J Neuroradiol. 2002;23 (2): 243-7. AJNR Am J Neuroradiol (full text) - Pubmed citation
- 3. Bell JW, Osborn AG, Salzman KL et-al. Neuroradiologic characteristics of astroblastoma. Neuroradiology. 2007;49 (3): 203-9. doi:10.1007/s00234-006-0182-0 - Pubmed citation
- 4. Agarwal V, Mally R, Palande DA et-al. Cerebral astroblastoma: A case report and review of literature. Asian J Neurosurg. 2012;7 (2): 98-100. doi:10.4103/1793-5482.98657 - Free text at pubmed - Pubmed citation
- 5. Louis DN, Ohgaki H, Wiestler OD, Cavenee WK "WHO Classification of Tumours of the Central Nervous System. 4th Edition Revised" ISBN: 9789283244929