Infratentorial Glioblastoma Metastasis to Bone.

Background: Glioblastoma multiforme (GBM) is a rapid-growing central nervous system neoplasm. We report a case of GBM with extensive intramedullary lumbar drop metastasis and highly unusual osseous spine metastasis from a primary infratentorial GBM occurring 10 years after the initial diagnosis, which to our knowledge has not been described previously.
Case Description: This 37-year-old man presented with new-onset headaches of increasing severity. Brain magnetic resonance imaging (MRI) demonstrated a heterogeneously enhancing mass in the left superior temporal lobe with adjacent edema. The lesion was initially biopsied in December 2006 and diagnosed as GBM (World Health Organization grade IV) with characteristic features of a highly cellular infiltrating glial neoplasm with nuclear pleomorphism, abundant microvascular proliferation, and abundant necrosis with pseudopalisading nuclei. Ki-67 immunostaining revealed that 15%-20% tumor cell nuclei were positive, indicating a high proliferative index. Histologically, this neoplasm demonstrated characteristic "cell wrapping." Immunoreactivity was variably but strongly positive for glial fibrillary acidic protein in neoplastic cells. In 2018, additional MRI revealed disease throughout the spine and bone biopsy of the thoracic spine showed the same glial neoplasm with primitive neuroectodermal tumor-like components (GBM-PNET).
Conclusions: This case is meant to highlight that, although rare, infratentorial GBM-PNET has a higher frequency of isocitrate dehydrogenase 1 (IDH1) mutation and may metastasize to the spine years after the initial diagnosis despite the likely better prognosis.
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