Glioblastoma NOS

Discussion:

The patient went on to have surgery. 

Histology

MICROSCOPIC FEATURES: Paraffin sections show extensive replacement of white matter by a densely hypercellular glial tumor. This is composed predominantly of fibrillary and gemistocytic astrocytes which show moderate nuclear and cellular pleomorphism. In addition, there is a minor oligodendroglial component. Frequent mitotic figures are identified. There is prominent microvascular proliferation with multi-layering of atypical cell around vascular lumens. Several areas of palisaded necrosis are also noted. These incorporate thin-walled necrotic and thrombosed blood vessels. Tumor extensively involves cerebral cortex and there is prominent peri-neuronal, perivascular and subpial secondary structuring. The features are of glioblastoma with a minor oligodendroglioma component (WHO Grade IV).

FINAL DIAGNOSIS: glioblastoma with a minor oligodendroglioma component

 

Note: IDH mutation status is not provided in this case and according to the current (2016) WHO classification of CNS tumors, this tumor would, therefore, be designated as a glioblastoma NOS

Note: The diagnosis of glioblastoma is actually not entirely established in this case as the IDH wild-type status has not been assessed. Although in this age group it is likely to reflect an IDH wild-type glioblastoma, it is possible that this is a IDH mutant glioblastoma (secondary glioblastoma). If an IDH mutation were to be found, then 1p19q codeletion status would also need to be established

This is important from a classification and prognosis point of view as if an IDH mutation was found and 1p19q was co-deleted then this tumor would actually represent an anaplastic oligodendroglioma and not a glioblastoma.

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