Objective: Malignant glioneuronal tumors show considerable morphological diversity. Their biological behavior and clinicopathological characteristics are incompletely understood. With the exception of anaplastic ganglioglioma, they are not assigned to a specific entity in the current WHO classification. It is also not clear whether histological features of these neoplasms influence prognosis.
Material and Method: We identified 36 glioneuronal tumors with malignant histological features among the departmental archives and neuropathology consultation files of the authors. We reviewed the pathological and radiological features of these tumors to construct a preliminary histological categorization.
Results: Based on their pathological features, we divided the study group into three histologically distinct categories: 1) glioneuronal tumors with a malignant glial component (anaplastic gangliogliomas); 2) glioneuronal tumors with a malignant neuronal/neuroblastic component; 3) glioneuronal tumors with both malignant neuronal and glial components. All tumors occurred in a younger age group compared to glioblastomas and appeared radiologically well-defined, cystic and solid with variable contrast enhancement. There was a high rate of local recurrence (29 of 36 patients) and 12 patients died during follow-up period. Median progression-free survival was less than 12 months, and did not differ among categories. Cerebrospinal tumor spread was seen in only one patient. Concurrent WHO grade I ganglioglioma and the presence of a malignant neuronal component did not appear to influence prognosis
Conclusion: MGNTs were considered in three simple categories based on their malignant component(s). Tumors in all categories exhibited a high rate of local recurrence and aggressive behavior akin to malignant gliomas as opposed to classical PNET. Nevertheless, MGNT demonstrated clinicopathological features that distinguish them from typical glioblastoma. The exact nosology of MGNTs is unresolved and our study underscores the need for a more comprehensive classification of these neoplasms within the WHO scheme.
