A rare case of oligodendroglioma with gangliocytic differentiation in a 31-year-old male: importance of genetic testing for IDH1/2.

We report a rare case of oligodendroglioma with gangliocytic differentiation. A 31-year-old male without a past medical history was admitted with a sudden seizure. On magnetic resonance imaging, an approximately 7-cm mass with necrosis was noted in the right frontal lobe. The patient underwent surgical resection. On microscopy, two morphologically distinct areas with oligodendroglioma- and ganglioglioma-like features were found. Immunohistochemistry showed an absence of CD34 expression, whereas isocitrate dehydrogenase 1 (IDH1) was positive in the glial component. Moreover, IDH1 was positive in the ganglion-like cells as well as in the glial component. Subsequent 1p/19q co-deletion was confirmed by fluorescence in situ hybridization. Finally, a diagnosis of oligodendroglioma with gangliocytic differentiation was made. IDH1/2 molecular test would be basic and essential diagnostic tool in central nervous system tumor of young patients.