Malignant transformation in a ganglioglioma with anaplastic neuronal and astrocytic components. Report of a case with flow cytometric and cytogenetic analysis.

Background: Malignant transformation of a ganglioglioma is rare and is generally restricted to the glial component. The authors described a unique case in which neuronal and glial elements exhibited anaplasia in a ganglioglioma. A subtotal resection of a large left temporal tumor extending into the diencephalon and brain stem in a 10-year-old boy revealed a ganglioglioma with no atypical features. The histologic findings were unchanged at further resections 4 and 12 months later. Radiotherapy was instituted with 5500 cGy in 30 fractions 21 months after initial resection. The patient returned 3 years later with a massive midline tumor recurrence.
Methods: The tumor was studied by conventional histologic methods, immunohistochemistry, flow cytometric methods, transmission electron microscopy, immune electron microscopy, and cytogenetic analysis.
Results: Although the first three resections revealed a typical ganglioglioma, the fourth resection revealed a cellular pleomorphic tumor with many multinucleated cells and mitoses. The tumor cells expressed glial fibrillary acid protein (GFAP) and synaptophysin on double labeling. By electron microscopy, intermediate filaments, microtubules and abundant rough endoplasmic reticulum, and neurosecretory granules were seen. Immune electron microscopy showed GFAP and synaptophysin within tumor cells. Flow cytometric studies revealed G0G1, 78%; S-phase, 9%; and G2M, 13%. Tumor cytogenetics on short term cultures revealed a complex abnormal karyotype with three sublines containing several structural chromosomal abnormalities.
Conclusions: A unique anaplastic transformation of a ganglioglioma is reported with the anaplastic cells exhibiting neuronal and astrocytic features.