Astroblastoma

Epidemiology and Etiology:

· Rare

· Precise criteria for diagnosis have not found wide acceptance

· Infants and young adults

· ?tanycyte differentiation or precursor

Common sites:

· intra-axial peripheral supratentorial lesion (almost always)

· involving the frontal and parietal lobes of a single hemisphere

· medial-sagittal site

· not intraventricular

Gross features:

· 3mm to 8cm

· Well-circumscribed

· Not usually infiltrative

· Lobulated

· Solid-cystic

· MRI

· Fairly characteristic uneven “bubbly” appearance of solid component on T2-weighted

Histologic features:

· Features of astrocytoma and ependymoma

· Perivascular astroblastic rosette (dominant and diffuse)

· Not specific (ependymoma, others)

· Abundant eosinophilic cytoplasm and short cytoplasmic processes that are anchored to blood vessel wall

· Stout and columnar or tapering processes

· Lack of fine fibrillarity of perivascular processes (differ from ependymoma)

· Perivascular hyalinization often (not typical in ependymoma)

· Papillary (?pseudopapillary) architecture maybe

· Pushing border commonly

· No infiltrating fibrillar component at tumour borders

· Epithelioid cells

· Calcification often

· High-grade / malignant features:

· High cellularity areas

· Anaplastic nuclei

· High mitotic index (>5/10HPF)

· Vascular proliferation

· Necrosis

· MIB1 (6-22%)

Immunophenotype:

Marker:	Sensitivity:	Specificity:
GFAP
S100
EMA	Variable, focal

Molecular features:

· Chromosomes 7, 10, 12, 21, and 22 are frequently involved in both numerical and structural changes

· (http://knol.google.com/k/micheal-miller/molecular-cytogenetic-analysis-in-the/2qtpmllakdowr/10#)

· CGH on 7 tumours (Brat et al, 2000):

· Not typical of ependymomas or astrocytoma

· No definite difference between low and high-grade

· 20q gains (4/7)

· Also 19 gains (3/7)

· Losses:

· 9q (2/7)

· 10 (2/7)

· X (2/7)

· Variable other imbalances

· Jay et al. (1993) – 1 tumour:

· 45,XX,-10,-21,-22,+mar1,+mar2

· By G-banding – mar1 ?chr10 material, mar2 ?pericentromeric Chr22 material with distal Chr22 deletion

· SKY (Squire et al, 2001):

· 45,XX,der(10)t(10;21)(q?;q11), −21,dup(22)(p?)

· Mar2 described above appears to be completely made up of 22 material on SKY (pic in the paper)

· Miraeu et al. (1999) – 1 tumour (high grade):

· 45,XX,del(1)(p36.1),del(11)(p13),der(14;15)(q10;q10),rea(22)(q11.2)

· I don’ know why they did not call it a t(11;22) because 11pter lit up on 22q

· Plus a tetraploid subclone with same abnormalities

· They also mention ANOTHER case from an abstract with a t(5;22) and a breakpoint at 22q11.2, and a deletion of 11p

·

Other features:

· EM:

· Similar features to ependymoma:

· Cytoplasmic intermediate filaments

· Surface and cytoplasmic microvilli

· Differing from ependymoma:

· Long intercellular junctions are poorly developed

· Cilia are rare

· Prognosis:

· Roughly divided into 2 groups:

· Low-grade / well-differentiated:

· Low rate of recurrence

· High-grade / malignant:

·

References:

· Salvati M, D’Elia A, Brogna C, et al. Cerebral astroblastoma: analysis of six cases and critical review of treatment options. Journal of Neuro-Oncology. 2009;93(3):369-378.

· Brat DJ, Hirose Y, Cohen KJ, Feuerstein BG, Burger PC. Astroblastoma: Clinicopathologic Features and Chromosomal Abnormalities Defined by Comparative Genomic Hybridization. Brain Pathology. 2000;10(3):342-352.

· Mierau GW, Tyson RW, McGavran L, Parker NB, Partington MD. Astroblastoma: ultrastructural observations on a case of high-grade type. Ultrastruct Pathol. 1999;23(5):325-332.

· Squire JA, Arab S, Marrano P, et al. Molecular cytogenetic analysis of glial tumors using spectral karyotyping and comparative genomic hybridization. Mol. Diagn. 2001;6(2):93-108.