Novel Perspectives Regarding CD34 Immunoexpression Patterns in Gangliogliomas

Gangliogliomas are extremely rare central nervous tumors composed of an admixture of glial and neuroepithelial elements. Gangliogliomas mainly affect the temporal lobe and occur in the pediatric population. There are several controversies in the scientific literature regarding these tumors, which debuted with the exclusion of grade II gangliogliomas in the 2006 edition of the current World Health Organization (WHO) classification. The upcoming edition due in the last months of 2021 is not expected to include changes regarding the current classification of glio-neuronal tumors. This vision has led to a number of articles that have pushed for the reintroduction of this category. However, these articles support the reintroduction of this degree in terms of prognosis and evolution, without providing clear criteria for the inclusion of certain gangliogliomas in this category. On the other hand, there are uncertainties about the relationship of gangliogliomas with focal cortical dysplasia. The coexistence of the two entities, as well as their succession are occasionally encountered in practice and have led to numerous studies that have tried to clarify the relationship between them. The most common and most accessible element in routine practice is the immunoreactivity for CD34. Both entities express this marker, and dual lesions express the highest percentage of immunoreactivity for CD34. In this article, we study the expression of CD34 on a series of cases including both grade I gangliogliomas and anaplastic gangliogliomas diagnosed between 2011 and 2020 in a Neuropathology Unit in Bucharest Romania.