Presentation
Patient presented with a few months of absence seizures. Otherwise well.
Patient Data
This scan was obtained by the patient's primary physician/general practictioner and scanned from printed film; thus the suboptimal image quality.
A right temporal mass, somewhat hyperdense pre-contrast demonstrates contrast enhancement and is surrounded by edema with resultant mass effect.
Centered within the lateral aspect of the right temporal lobe (middle temporal gyrus) with a cortical/subcortical origin is an intra-axial multilobulated predominantly solid mass with cystic components. The solid mass is hypo to isointense on T1 and slightly hyperintense on T2 imaging. The cystic component is hypointense on T1 and hyperintense on T2.
Mild diffusion restriction with relatively low ADC values (only slightly higher than normal brain) suggests increased cellularity of the solid component. There is T2/FLAIR signal abnormality in keeping with vasogenic edema extending from the right temporal lobe into the anterior parietal lobe, into the posterior aspect of the sub-insular region and the lateral aspect of the posterior limb of the internal capsule. On post-contrast imaging, the solid component of the lesion enhances vividly with non-enhancement of the cystic component. No evidence of blood products within the lesion.
The mass causes expansion of the lateral aspect of the temporal lobe, with effacement of sulci and enlargement of gyral folds. There is a local mass effect but no midline shift or uncal herniation. No hydrocephalus. There is the suggestion of subtle bony remodeling and thinning of the adjacent skull.
MRS with the voxel placed over the solid enhancing component of the lesion demonstrates an increase in Choline and mildly reduced NAA (not shown). There is increased CBV within the solid enhancing component.
The patient went on to have a craniotomy and resection of the lesion.
The sections show a densely cellular glial tumor. It is relatively well-demarcated from the surrounding cerebral cortex, though the occasional single tumor cells are present in the cortex. Some of the tumor cells are markedly pleomorphic. They have enlarged hyperchromatic nuclei with frequent intranuclear pseudoinclusions, multinucleation and inconspicuous nucleoli. The cytoplasm is focally foamy and "xanthomatous". Other tumor cells are more spindled with elongated nuclei and cytoplasm. Small numbers of tumor cells are seen at the grey-white matter junction. Many eosinophilic granular bodies are seen. There is perivascular cuffing of lymphocytes. Very sparse mitoses are identified (0-1 mitosis per 10 high-power fields). There is no evidence of endothelial cell hyperplasia or necrosis.
The tumor cells are GFAP positive, and focally synaptophysin and NeuN positive (not shown).
The Ki-67 index is about 1-2%. The features are those of pleomorphic xanthoastrocytoma.
Final diagnosis
Pleomorphic xanthoastrocytoma (WHO grade II).
Case Discussion
This case which highlights the differential of a temporal lobe mass in a young patient. The differential on imaging is largely between a pleomorphic xanthoastrocytoma (although degree of edema is unusual), a ganglioneuroma and a pilocytic astrocytoma (position is atypical)
DNETs usually do not enhance so vividly. Other more aggressive gliomas (e.g. GBM) tend not to have such a homogeneously enhancing nodule and do not have evidence of bony re-modelling.
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