Astroblastoma: Clinicopathologic Features and Chromosomal Abnormalities Defined by Comparative Genomic Hybridization

Abstract

Astroblastomas are uncommon brain tumors whose classification and histogenesis have been debated. Precise criteria for diagnosis have been described only recently, but have not found wide acceptance. We report the clinical, radiographic, and histopathologic features of 20 astroblastomas, and the chromosomal alterations in seven cases as detected by comparative genomic hybridization (CGH). The tumors occurred both in children and young adults (average age, 14 years), most often as well circumscribed, peripheral, cerebral hemispheric masses. Radiographically, the lesions were contrastenhancing and solid, often with a cystic component. All were characterized histologically by astroblastic pseudorosettes, and most displayed prominent perivascular hyalinization, regional hyaline changes, and pushing borders in regard to adjacent brain. Tumor cells were strongly immunoreactive for S‐100 protein, GFAP, and vimentin. Staining for EMA was focal. Ten of 20 astroblastomas were classified as “well differentiated” and 10 were classified as “malignant,” largely on the basis of hypercellular zones with increased mitotic indices, vascular proliferation, and necrosis with pseudopalisading. All 10 well differentiated lesions and 8 of 10 malignant lesions were completely resected. None of the well differentiated astroblastomas recurred within the limited follow‐up period. Three malignant astroblastomas recurred, including two incompletely resected tumors, and one that had been totally resected. One patient died of disease following recurrence. The most frequent chromosomal alterations detected by CGH were gains of chromosome arm 20q (4/7 tumors) and chromosome 19 (3/7). The combination of these gains occurred in three, including two well differentiated and one malignant astroblastoma. Other alterations noted in two tumors each were losses on 9q, 10, and X. These chromosomal alterations are not typical of ependymoma or infiltrating astrocytic neoplasms, and suggest that astroblastomas may have a characteristic cytogenetic profile in addition to their distinctive clinical, radiographic, and histopathologic features.

A case of cerebral astroblastoma with rhabdoid features: a cytological, histological, and immunohistochemical study

“…The typical histopathological features of astroblastoma are the perivascular pseudorosette of GFAP-positive cells with short and stout cytoplasmic processes, radiating towards central blood vessels that often demonstrate sclerosis [3][4][5]. Other histological characteristics are lack of fibrillary background and compressing rather than infiltrative margin [6,7].…”

Complete surgical resection of high-grade astroblastoma with long time survival: case report and review of the literature

“…Focal or multifocal regions of high cellularity, anaplastic nuclear features, elevated mitotic indices (>5 per 10 HPF), vascular proliferation and necrosis with pseudopalisading correspond to this high-grade group 4 .…”

“…Brat et al 4 , using comparative genomic hybridization, detected chromosomal abnormalities in every case studied, the gain of 20q being the most frequent. Although the spectrum of chromosomal alterations indicated that astroblastoma may have its own genetic profile, none of the detected anomalies were specific for malignancy.…”

“…Although its existence has been questioned by some investigators 21 , it is now recognized as a distinct clinicopathological entity 4 , probably representing less than 0.5% of gliomas 17 . It usually appears in young-adult patients, although congenital cases have also been described 13 .…”

Astroblastoma; case report and review of literature

“…Moreover, the origin of these tumors has been debated, because they share common histological characteristics with ependymomas and astrocytomas. Recent studies suggested that astroblastoma is a distinct histological and genetic entity (6,7,31,39). It has a distinctive characteristic of perivascular pseudorosettes with frequent vascular hyalinization.…”