Astroblastoma: a case report

Abstract

Astroblastoma is one of the very unusual type of tumors, whose histogenesis has not been clarified. It occurs mainly among children or young adults. Astroblastoma is grossly well-demarcated, and shows histologically characteristic perivascular pseudorosettes with frequent vascular hyalinization. Perivascular pseudorosettes in astroblastoma have short and thick cytoplasmic processes and blunt-ended foot plates. A 15-yr-old girl presented with headache and diplopia for one and a half year. A well-demarcated mass, 9.7 cm in diameter, was found in the right frontal lobe in brain MRI, and it was a well-enhanced inhomogenous mass. Cystic changes of various sizes were observed inside the tumor mass as well as in the posterior part of the mass, but no peritumoral edema was found. Histologically, this mass belongs to a typical astroblastoma, and no sign of anaplastic astrocytoma, gemistocytic astrocytoma or glioblastoma was found in any part of the tumor. Immunohistochemically, the tumor cells showed diffuse strong positivity for glial fibrillary acidic protein, S-100 protein, vimentin and neuron specific enolase, and focal positivity for epithelial membrane antigen and CAM 5.2, while showing negativity for synaptophysin, neurofilament protein, pan-cytokeratin and high molecular weight keratin.

Fig. 1

(A) T1-weighted image shows a huge well-demarcated mass in the right frontal lobe. (B) Many cystic changes of different sizes are observed within the tumor on T2-weighted image. (C) The tumor shows an inhomogenous enhancement.

Fig. 2

Well-developed perivascular pseudorosettes are seen throughout the tumor (H&E, ×40).

Fig. 3

The tumor cells composing perivascular pseudorosettes display short and thick cytoplasmic processes with prominent blunt-ended footplates toward the vessel wall (H&E, ×400).

Fig. 4

The fibrovascular stroma frequently shows prominent vascular sclerosis (H&E, ×40).

Fig. 5

The broad GFAP-positive glial processes surround blood vessels (×400).

Fig. 6

The tumor cells are positive for S-100 protein (A), vimentin (B), and CAM 5.2 (C) (×200).