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Epilepsy-associated tumours: what epileptologists should know about neuropathology, terminology, and classification systems Volume 18, numéro 3, September 2016

Figure 1

Histopathological challenges in the diagnosis of LEATs. Upper row shows two ganglioglioma variants. Compared to variant 2 (C-D), variant 1 (A, B) did not reveal any significant neuronal component on high magnification H&E (haematoxylin and eosin) staining (A), and one may argue that neurons are over-run by neoplastic glial cells. However, there is significant CD34 immunoreactivity (brownish colour in [A]), as well as dysplastic neurons in other areas of this specimen (not shown). The lower row demonstrates two tumours with an oligodendroglial (clear) cell component; microscopic inspection on H&E staining can be challenging. DNT WHO grade I (E-F) without IDH1 mutation. Oligodendroglioma WHO grade II (OII) (G-H) with IDH1 mutation.

Figure 2

Post-surgical MRI following tumour vs. epilepsy surgery. (A, C) MRI 40 months after first surgery (at age 14 months). (B ,D) MRI after repeat surgery at age 6 years. The red dot in (C) indicates seizure onset recorded from subdural grids, strips, and depth electrodes. Broca's area could not be determined by direct electrical cortical stimulation, however, based on the result of invasive recording, a resection of the pars triangularis and pars opercularis frontalis was not necessary. Courtesy of P. Winkler, Olga Hospital Stuttgart & Neuropediatric Clinic and Clinic for Neurorehabilitation, Epilepsy Center for Children and Adolescence, Schoen-Kliniken Vogtareuth, Germany.

Figure 3

Variable microscopic appearance at the first and second operation. (A-C) Surgical specimen from first operation (diagnosis: anaplastic astrocytroma). (A) Diffusely infiltrating tumour of moderate cellularity in a glial matrix and with few large neurons (arrow). (B) Neocortical infiltration of tumour cells; arrow points to a small amount of calcification. (C) Area of tumour with maximum proliferation (approx. 5%). No further staining for CD34, MAP2, or IDH1 were available at the local hospital. (D-I) Surgical specimen from the second operation (histopathological diagnosis: composite glio-neuronal tumour with atypical features (analogue WHO grade II). (D) Nodular tumour growth (arrow) with characteristic features of a DNT. (E) Astroglial tumour component with moderate cellularity and increased proliferation activity (I). (F) Glio-neuronal component with clusters of dysplastic neurons (arrow), not otherwise explicable by anatomical features. MAP2 staining pattern was also variable in this tumour with densely immunoreactive tumour cells (G), compared to areas in which MAP2 was restricted to dysplastic neurons (arrow in [H]). H&E staining (A-B, D-F); proliferation marker Ki67 (C, I); MAP2 immunohistochemistry (G-H). Scale bar in (A)=50 μm, applies also to (B, E-I); scale bar in (C)=100 μm; scale bar in (D)=250 μm.