Presentation
Patient referred due investigation for multiple sclerosis.
Patient Data
A hyperintense T2/FLAIR lesion occupies the immediately subcortical white matter of the anterior portion of the left inferior frontal gyrus. It measures approximately 11 mm in greatest diameter. It shows no restricted diffusion nor pathological contrast enhancement (not shown).
This patient did not fulfill radiologic criteria for MS. It was opted for keeping a follow-up.
Comparison is made to the previous MR scans. The previously noted mass lesion lying in the left pars triangularis has increased in size progressively along the time. The appearances do not suggest an area of demyelination. The lesion is well demarcated and measures approximately 15 x 10 x 14 millimeters. No surrounding vasogenic edema. MR perfusion, spectroscopy show normal appearance. No contrast enhancement is identified. Appearances suggest either a low-grade glioma or an area of cortical dysplasia. The relative homogeneous appearance of the lesion is against a diagnosis of ganglioglioma or DNET.
Biopsy was performed:
MICROSCOPIC DESCRIPTION: 1-3. The sections show features of a moderately cellular astrocytic tumor. The tumor cells have mildly enlarged round and hyperchromatic nuclei with short cytoplasmic processes in a fibrillary and focally microcystic background (most likely protoplasmic astrocytes). Occasional tumor cells extend into the cerebral cortex. Mitoses are inconspicuous. No endothelial cell hyperplasia or necrosis is present. There is no oligodendroglial component. The features are those of diffuse astrocytoma. The tumor cells are IDH-1, p53 and p16 positive. The topoisomerase index is 1-2%. MGMT immunostain is negative.
DIAGNOSIS: 1-3. Brain tissue: Diffuse astrocytoma (WHO Grade II).
Evidence of previous craniotomy. The left frontal lobe lesion shows a gradual increase in size, the lesion is now measuring approximately 18 x 21 mm in axial dimension. A subtle area of enhancement is now evident within the anteromedial aspect of the lesion which has gradually become more apparent over this time and corresponds to an area of marginal increase in CBV. In all other respects the scan is unchanged throughout the remainder of the brain.
Conclusion: Increase in size with evidence of enhancement suggests an area of possible deterioration in grade within the lesion.
The patient underwent to a surgical resection of the lesion.
MICROSCOPIC DESCRIPTION: The sections show features of a moderately cellular astrocytic tumor. The tumor cells are of mixed fibrillary and protoplasmic types. The former cells have elongated, angulated and hyperchromatic nuclei, the latter with rounder nuclei. 1 mitosis is noted. No microvascular proliferation or necrosis is present. There is no oligodendroglial component. The features are those of diffuse astrocytoma. The tumor cells are p53 and IDH-1 positive (good prognosis). The topoisomerase index is about 2%. There is loss of ATRX staining (mutated). MGMT immunostain is negative.
DIAGNOSIS: Frontal lobe lesion: Recurrent diffuse astrocytoma (WHO Grade II).
Case Discussion
This case demonstrated the indolent progression of a left lobe low-grade tumor that was histologically proven to be a diffuse astrocytoma (WHO grade II). It is important to emphasize that no enhancement is often the rule for these tumors, but small ill-defined areas of enhancement are not rare; however, when enhancement is seen it should be considered as a warning sign for progression to a higher grade.
This tumor expressed: IDH1 positive = mutation present = better prognosis
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