Structural MRI.Arrows show an intracortical cystic lesion that is hyperintense on T2-weighted images (top row, axial) and hypointense on T1-weighted images (middle row, axial), without enhancement (bottom row, coronal).
Interictal PET. Arrows show a focal area of moderate hypometabolism in the right posterior mesial parietal convexity.
Interictal EEG.Box shows an interictal discharge with maximal negativity at CZ with a broad bilateral parasagittal field (F4-C4-P4 and C3-P3).
Microscopic features of the resected tumour. (A) Low-power with H&E stain showing a mildly hypercellular neoplasm of bland cells with scattered microcystic areas filled with myxoid material. (B) High-power with H&E stain showing rare floating neurons (arrows) on a background of small oligodendrocyte-like cells. (C) Immunohistochemistry is negative for IDH1 R132H which is frequently present in oligodendrogliomas. (D) Immunohistochemistry is positive for Neu-N in rare neurons. Scale bar = 100 μm.