Glioblastoma NOS (with primitive neuronal component)
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Heterogeneous left frontal lobe mass with areas of non-enhancement embedded within enhancing tumor. The tumor extends accross the corpus callosum.
The patient went on to have a biopsy.
Paraffin sections show a densely hypercellular glial tumor. This is composed predominantly of pleomorphic, strongly GFAP immunoreactive astrocytic cells with irregularly shaped hyperchromatic nuclei and coarse processes. Scattered gemistocytic and multinucleated forms are also noted. There are frequent mitotic figures, prominent vascular endothelial cell hyperplasia and areas of confluent necrosis. The features are of glioblastoma.
Tumor in other specimens is composed of smaller cells with round, oval and angulated hyperchromatic nuclei and a small amount of cytoplasm. The majority of these cells show strong immunostaining for synaptophysin. Patchy strong GFAP staining is also noted. The features in this component are similar to primitive neuroectodermal tumors.
Final diagnosis: glioblastoma with PNET-like component.
Note: The current (2016) WHO classification of CNS tumors has made substantial changes to tumors previously considered to be PNET, now classified as embryonal tumors with multilayered rosettes (ETMR). In contrast, when a glioblastoma demonstrates similar histological features it is now referred to as a glioblastoma with primitive neuronal component