Atypical cell clusters expressing both neuronal and oligodendrocytic markers: Novel histological pattern of glioneuronal tumors?

Abstract

Glioneuronal tumors are a group of brain tumors that consist of both neuronal and glial cells. The spectrum of glioneuronal tumors is currently expanding, and many atypical glioneuronal tumors require further characterization. Two patients are described who had an atypical glioneuronal tumor with peculiar pathological features. One patient was a 7-year-old girl with a tumor in the right cerebellar hemisphere. This patient had no recurrence after total resection. The other was a 37-year-old man with a tumor in the spinal cord. He suffered incessant recurrence and received operative treatment four times. Although the clinical features (age at diagnosis, tumor location, and recurrence) were very different in these patients, the tumors had a characteristic common feature of atypical cell clusters. Intriguingly, the tumor cells in the clusters expressed both neuronal and oligodendroglial markers, indicating aberrant differentiation. Furthermore, the cluster-forming cells had modest proliferative indices and CD133 expression, indicating their role in the growth of the tumor. It is believed that these atypical cell clusters are a novel pattern of differentiation of glioneuronal tumors and that they need further investigation.