Here, we show that gemistocytic astrocytomas carry a lower frequency of IDH mutations than fibrillary astrocytomas (74% vs 92%; p = 0.0255) but have profiles similar to those of fibrillary astrocytomas with respect to TERT promoter mutations (5% vs 0%), 1p/19q loss (10% vs 8%), and loss of heterozygosity 10q (10% vs 12%).
Alterations in RRAS and ERCC1 appear to be typical in gemistocytic astrocytomas and secondary glioblastomas, since they were not present in 49 fibrillary astrocytomas or 30 primary glioblastomas.
Further screening showed RRAS homozygous deletion in 7 of 42 (17%) gemistocytic astrocytomas and in 3 of 24 (13%) IDH1 mutated secondary glioblastomas.
Alterations in RRAS and ERCC1 appear to be typical in gemistocytic astrocytomas and secondary glioblastomas, since they were not present in 49 fibrillary astrocytomas or 30 primary glioblastomas.
But, SYCP3 transcripts were found in four tumor samples (moderately differentiated gemistocytic astrocytoma, pituitary adenoma, glioma and an ovarian tumor).
Therefore it appears that GAs should not be uniformly graded as grade II but should be subdivided into grades II and III neoplasms based on histological features and MIB-1 LI.
Therefore it appears that GAs should not be uniformly graded as grade II but should be subdivided into grades II and III neoplasms based on histological features and MIB-1 LI.
Gemistocytic astrocytoma is characterized by a predominance of large astrocytes with plump processes and massive accumulation of glial fibrillary acidic protein (gemistocytes).
These results indicate that p53 mutations are a genetic hallmark of gemistocytic astrocytomas, whilst PTEN mutations are absent in low-grade and rare in anaplastic gemistocytic astrocytomas.
LOH 1p/19q typically occurred in tumors without TP53 mutations and were most frequent in oligodendrogliomas (69%), followed by oligoastrocytomas (45%), but were rare in fibrillary astrocytomas (7%) and absent in gemistocytic astrocytomas.
DNA sequencing, performed in 84% of cases, revealed that TP53 mutations were most frequent in gemistocytic astrocytomas (88%), followed by fibrillary astrocytomas (53%) and oligoastrocytomas (44%), but were infrequent (13%) in oligodendrogliomas.
In this study, gemistocytes and non-gemistocytic neoplastic cells were separated by laser-assisted microdissection from six gemistocytic astrocytomas carrying TP53 mutations.
These results indicate that p53 mutations are a genetic hallmark of gemistocytic astrocytomas, whilst PTEN mutations are absent in low-grade and rare in anaplastic gemistocytic astrocytomas.