LAUSR

BACKGROUND rosette forming glioneuronal tumors (RGNTs) with multifocal growth throughout the ventricular system are extremely rare, and only one case of RGNT with dissemination limited to supratentorial ventricles has previously been reported. Recent evidence based on molecular data suggest that low grade glioneuronal tumors (GNTs) involving the septum pellucidum and the lateral ventricles, with either DNET-like or RGNT-like features, may belong to a neuropathological entity distinct from cortical DNET and "typical" fourth ventricle RGNT respectively. Given their rarity, the classification of these neoplasms is still uncertain and their clinico-pathological and radiological aspects are only partially known. CASE DESCRIPTION A 24-year-old male presented a GNT with RGNT-like morphological features centered in the septum pellucidum with multifocal masses occupying the lateral ventricles and the third ventricle with extra-ventricular infiltration of the frontal lobe. The patient underwent STR and 4 years follow-up. The clinico-pathological and radiological features of the neoplasm are discussed. CONCLUSION multiparametric MR imaging (including MRS and PWI) may provide valuable information in the differential diagnosis between rare GNTs and other more frequent intra-ventricular neoplasms. In the present case, the enhancing remnant portion of the tumor showed remarkable CE variability during the follow-up with slow in situ progression. However, available data suggest that spontaneous CE "fluctuations" over time in RGNT may not represent a reliable indicator of tumor behavior.