Diffuse astrocytoma NOS (thalamic)
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There is a large lesion arise from both left & right side of thalamus (bigger on left side) protruding up & compressing the lateral ventricles with a degree of hydrocephalus. The lesion shows heterogeneous signals best seen on T2 image. The lesion shows no enhancement after admission of contrast, but does restrict on DWI.
MRS demonstrates a perfect tumor trace, with elevation of choline and reduction of NAA.
This patient went on to have a stereotactic biopsy which confirmed the diagnosis of a thalamic diffuse astrocytoma, of which low-grade has a much poorer prognosis than similar tumors in other locations.
Today, it would be important to test this tumor for H3 K27M mutation as there is a reasonable chance that it represents a diffuse midline glioma H3 K27M–mutant
Note: IDH mutation and H3 K27M mutation status is not provided in this case and according to the current (2016) WHO classification of CNS tumors, this tumor would, therefore, be designated as a diffuse astrocytoma NOS.