Glioneuronal tumor with neuropil-like islands: a new entity.

Glioneuronal tumor with neuropil-like islands (GTNI) is a distinctive and rare tumor characterized by both glial and neuronal differentiation. However, unlike other mixed glioneuronal tumors, which are characterized by a favorable prognosis, this neoplasm has been found to be potentially aggressive. We report here a case arising in a 60-year old male patient who presented with seizures, forgetfulness and right-sided hemiparesis, due to a left frontal lobe tumor. Unlike most cases described in the literature, the present tumor was unique in its radiological appearance, which was cystic. On microscopic evaluation, the glial component was chiefly gemistocytic punctuated by neuropil-like islands. Strong nuclear immunolabeling of p53 and absence of 1p/19q deletion by fluorescence in situ hybridization assay were consistent with those in previous reports.