Angiocentric gliomas are WHO grade I tumors, classified within a subgroup of gliomas that includes astroblastomas and chordoid gliomas of the third ventricle (2). They are rare tumors with few reported cases or case series. Interestingly, almost all such tumors present with simple partial or complex partial seizures, or in some cases with status epilepticus. Furthermore, they are also characterized by drug-resistant seizure (3).
Microscopy reveals infiltrative characteristics in angiocentric gliomas. Bipolar cells are arranged in an elongated, monomorphous, and angiocentric pattern along cortical blood vessels. There are also pseudorosettes of ependymoma-like, subpial aggregates and miniature schwannoma-like nodules. There is usually no mitosis and limited vascular proliferation. Immunohistochemistry shows positive results for epithelial membrane antigen (EMA) and variable results for glial fibrillary acidic protein (GFAP), S-100 protein, and vimentin (VIM)(2, 3).
The main differential diagnosis to be considered alongside angiocentric glioma is ependymoma. Given that the microscopic appearances of both possess similar features, such as perivascular rosettes, histopathological differentiation between these two tumors can be a challenge. However, determining the diagnosis is of considerable practical importance due to differences in respective prognosis. Supratentorial ependymoma is considered a WHO grade II tumor. However, while characterized as a low-grade tumor, supratentorial ependymoma can relapse and disseminate, frequently requiring adjuvant therapy and surgical reinterventions. In contrast, angiocentric glioma, a WHO grade I tumor, is rarely associated with relapse or malignant transformation following complete surgical resection. Other differential diagnoses include astroblastoma and astrocytoma (2, 3).
Recently, Zhang, J.(4) found MYB rearrangements in groups of patients with angiocentric gliomas. Genomic analysis of angiocentric gliomas revealed a tripartite mechanism involving MYB-QKI rearrangements, which suggests a different tumor profile that separates angiocentric gliomas from others gliomas (1).
This case endorses that angiocentric glioma may be present, albeit more rarely, in brain regions such as the thalamus and not necessarily be associated with seizures. Additionally, the MYB rearrangement should be seen as a potential genetic alteration to characterize the angiocentric gliomas in the new area of pathologic definitions aided by genetic profiles.
Acknowledgments: The authors would like to thank Dr. Brent Alan Orr, MD, PhD. and Dr. David Ellison, MD, PhD. for performing the pathology review at St. Jude Children's Research Hospital.
Contributed by Sergio Cavalheiro, MD, PhD, Marcos Devanir Silva da Costa, MD, MSc, Cristina Góes Schaurich, MD, Andrea Maria Cappellano, MD, Nasjla Saba-Silva, MD, Maria Teresa de Seixas Alves, MD, PhD, João Norberto Stavale, MD, PhD