Synchronous multicentric glioblastoma with PNET and O subtypes: Possible pathogenesis

Background: Glioblastomas (GBM) are highly infiltrative, cellular and mitotically active tumors with large histologic variations within and between tumours. Several subtypes have been described including the GBM with oligodendroglial differentiation (GBM-O) and primitive neuroectodermal tumour components (GBM-PNET). We report the first described case of a patient with synchronous multi-centric GBM-O and GBM-PNET components. Case Description: A patient, who presented with a short history of progressive headache and difficulty with memory recall, was found on MRI imaging to have two intracranial lesions. These showed heterogeneous enhancement and were found in the left frontal and left temporal regions. The patient underwent gross total resection of these two lesions which were found to show GBM-O and GBM-PNET differentiations. Conclusion: Although tumour cell migration in the context of GBM is a well-recognized phenomenon, the traditional hypothesis is not able to satisfactorily explain this case of multicentric GBM whereby the two lesions demonstrate different cell origins. More current understanding of the migratory pathways from the subventricular zone provide an alternate and plausible pathway that fits our patient's unusual diagnosis.