In consideration of the morphology and of the location of the enhancing lesion the diagnosis of the glioblastoma multiforme was placed. The patient was sent for a stereotactic needle biopsy of the frontal mass which conclude for astrocytoma grade IV (GBM). (Fig2)

The histology revealed a tumoral proliferation composed of gemistocytes and elongated cells with fibrillary process. Marked nuclear pleomorphism mitotic figures and numerous apoptotic cells were also seen as well with an area of necrosis and foci of endothelial proliferation.

The immunoistochemistry for GFAP was strongly positive and the proliferation index estimated by MIB-1 was high, reaching at 15% in a large part of the tumour. Immunoistochemistry for P53 was also positive. The patient was then referred for chemotherapy and radiotherapy.

DISCUSSION
Multiple cerebral lesions as the case the Authors described, could represent GBMs, metastases, even if the primary site of malignancy could not be identified; lymphoma because of multifocal pattern of lesion with spread along the corpus callosum, involvement of the infundibulum and the hypothalamus. However, multifocal GBM, even though the hypothalamus is a rare location, could result in this pattern and the cortical abnormality in the left parietal lobe could be compatible with a different stage of the same pathology and could be considered a low grade glioma.

Multiple high-grade gliomas (GBM) have been classified as: A) multicentric if they arise independently in more than one side of the cerebral hemisphere and B) multifocal if they spread from a primary focus to other areas of the brain. However this distinction does not have practical clinical value and gliomas have been categorized as early if they present at the initial diagnosis or late if they present during the treatment^2,3,5. Dissemination can occur intracranially or throughout the spinal axis and various patterns of spread have been described in the literature^3,4. In the most recent literature three subtypes of intracranial dissemination based on MRI characteristic have been described; Type I; a single location of GBM is present associated to subependymal or subarachnoid spread at sites distant from the primary tumour location; Type II; a multifocal GBM is present associated to subependymal or subarachnoid spread; Type III, multifocal GBM displays subependymal or subarachnoid spread at sites distant from the primary tumour location.¹ According to this classification the case we describe represents a Type III. To our knowledge no Type III has been yet described in the literature. In particular the characteristics of lesions in different degrees of malignancy as suspected on the MRI is an extremely rare event.

CONCLUSION

In conclusion, multifocal GBM can be diagnosed on the first MRI as we have illustrated in this case.
Because of the subependymal spread, we include this unique case as Type III according to the recent classification proposed by Parsa et al. A focus of lower grade was likely preexisting in this case, making it a different subtype.

REFERENCES

1. Parsa AT, Wachhorst S, Lamborn KR et al. Prognostic significance of intracranial dissemination of glioblastoma multiforme in adults. J Neurosurg 102: 622-628; 2005
2. Kyritsis AP, Levin VA, Yung WKA et al. Imaging pattern of multifocal gliomas. European Journal of Radiology 16:163-170; 1993