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An area of signal change on the flair and T2 with slight positive mass effect is identified in the medial and anterior aspect of the superior right frontal gyrus. The signal change extends into the cortex which is also is thickened.
A leading-edge of signal abnormality extending down to the ventricle is not clearly identified but would necessitate high-resolution 3-D Flair imaging
No contrast-enhancement is associated with the lesion. No raised cerebral blood volume (CBV).
MR spectroscopy shows a decrease of metabolites without increased choline and without increased myoinositol peak.
No other lesions are identified
Conclusion: An area of signal abnormality with mass effect is present within the superior frontal gyrus on the right. Differential diagnosis lies between cortical dysplasia and low-grade glioma. Spectroscopic findings would favor cortical dysplasia.
The patient underwent resection of the right frontal lesion.
Microscopy: The sections show cerebral cortex and white matter. Cortical laminar architecture is preserved with no features of cortical dysplasia seen. There is prominent perineuronal secondary structuring. White matter contains a population of atypical glial cells with oligodendroglial morphological features - enlarged round and oval hyperchromatic nuclei, some with perinuclear clearing and a paucity of processes. Several groups of overlapping nuclei are noted. No mitotic figures are identified. There is no microvascular proliferation and no necrosis is seen. A population of reactive astrocytes is also present.
- GFAP negative in atypical oligodendroglial cells
- positive in reactive astrocytes
- NogoA positive in atypical oligodendroglial cells
- IDH-1 R132H positive (mutated)
- ATRX positive (not mutated)
- p53 negative
- MGMT positive (likely unmethylated)
- p16 CDKN2A positive
Topoisomerase labeling index: Approximately 1%.
The features are of IDH-1 mutated diffuse glioma (WHO II) strongly favoring oligodendroglioma.
Diagnosis: Right frontal tumor: IDH-1 mutated diffuse glioma (WHO II) with features strongly favoring oligodendroglioma. FISH for chromosome 1p/19q deletion is recommended.
Supplementary report: FISH for chromosome 1p/19q deletion. 1p36 NO DELETION DETECTED 19q13.3 NO DELETION DETECTED Number of cells scores 200 Number of sites scored 10 1p36/1q25 ratio 1.00 19q13.3/19p13 ratio 1.00
REFERENCE CRITERIA: 1p36/1q25 ratio <0.8 Deletion detected 19q13.3/19p13 ratio <0.8 Deletion detected
Therefore, the right frontal lesion represents a diffuse astrocytoma.