Presentation
Treatment resistant seizures.
Patient Data
The right mesial temporal lobe (involving the hippocampal body and parahippocampal gyrus, but sparing the amygdala) is expanded by a high T2 signal fairly rounded region with high signal extending up the hippocampal tail. There is no convincing abnormal contrast enhancement. ADC values are facilitated (1600 x 10^-6 mm^2/s) and other than one questionable focus, there is no convincing elevation of cerebral blood volume. MR spectroscopy demonstrates elevation of choline and myo-inositol (not shown).
The remainder of the brain is unremarkable in appearance.
Conclusion:
The right mesial temporal lobe lesion, unchanged when compared to prior MRI studies (not shown) is consistent with a low-grade diffuse glioma.
Case Discussion
The patient went on to have a resection.
Histology
There are fragments of brain parenchyma infiltrated by a cellular tumor composed of cells with large, irregular, hyperchromatic nuclei arranged haphazardly within a fibrillary background. There are scattered cells with marked nuclear pleomorphism. Mitoses are readily identified, with up to five identified per 10 high-power fields. There is no necrosis or microvascular proliferation.
Immunohistochemistry
GFAP: Positive
Olig2: Positive
IDH-1 R132H: Negative (non-mutated)
ATRX: Retained (non-mutated)
D34: Diffuse pericellular staining and scattered cells with ramified processes in lesional tissue
EMA: Negative
Synaptophysin: Negative
Chromogranin: Negative
NeuN: Negative
CD68: Negative
H3-K27M: Negative
BRAF V600E: Negative in tumor cells
p53: Patchy weak positivity (wild-type staining)
p16: Occasional positivity in some cells
ki-67: 1-2%
Next generation sequencing glioma panel
1p/19q codeletion: Not detected
EGFR amplification: Not detected
IDH1 codon 132: No pathogenic variant detected
IDH2 codon 172: No pathogenic variant detected
BRAF codon 600: No pathogenic variant detected
H3F3A codons 27 and 34: No pathogenic variant detected
TERT promoter Chr5:1295228 (C228T) and chr5:1295250 (C250T): No pathogenic variant detected
Final diagnosis
Polymorphous low-grade neuroepithelial tumor of the young, WHO Grade I.
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