Malignant transformation of a desmoplastic infantile ganglioglioma in an infant carrier of a nonsynonymous TP53 mutation.

INTRODUCTION: Desmoplastic infantile ganglioglioma is a rare intracranial neoplasm classified as World Health Organization grade I tumor under neuronal and mixed neuronal-glial tumors (2007 World Health Organization brain tumor classification). It is usually a good prognosis, but 40% of patients require further medical, radiation, and/or surgical intervention, and 15% develop leptomeningeal spread or die from desmoplastic infantile ganglioglioma. Transformation to malignant glioblastoma occurs, but the genetic alterations associated with the transformation are generally unknown.
METHODS: We describe a desmoplastic infantile ganglioglioma in a 2-month-old boy, which showed aggressive behavior, requiring debulking at 2.5 months of age and chemotherapy at 10 months of age after tumor progression. At 8.5 years of age he developed malignant transformation to glioblastoma. Chromosome microarray analysis using oligo array and genomic sequencing was performed on the biopsy specimen from 2 months of age and on the subsequent transformed malignant glioblastoma.
RESULTS: After being clinically stable for 7.5-years, transformation to glioblastoma transformation occurred. He did well for 1 year but subsequently died from tumor progression. Chromosome microarray analysis using oligo array performed on the biopsy specimen obtained at 2 months of age did not reveal significant abnormalities; but there were significant genomic deletions and duplications associated with the glioblastoma. These included multiple genomic losses involving 4q and Y, gains of 5q, and amplification of 12q14. Genomic sequencing revealed a single nucleotide variant, p.R248Q in exon 7 of TP53, in the primary desmoplastic infantile ganglioglioma and the glioblastoma multiforme.
CONCLUSIONS: The nonsynonymous variant (p.R248Q in exon 7) of the TP53 gene is predicted to alter the structure of the L2/L3 motif of the DNA binding domain of p53 protein. It was detected in the primary desmoplastic infantile ganglioglioma and glioblastoma multiforme. This child illustrates the rare recurrence of desmoplastic infantile ganglioglioma with malignant transformation to glioblastoma caused by a nonsynonymous TP53 mutation, providing explanation for other rare benign tumor transformations. The TP53 gene is a known primary site of genetic alteration that predisposes to malignant tumors, and this case indicates that it might also be involved in the behavior and outcome of desmoplastic infantile ganglioglioma. Therefore more genetic testing is recommended on desmoplastic infantile ganglioglioma tumors, which may provide biologic prognostic markers.