Pathological spectrum of neuronal/glioneuronal tumors from a tertiary referral neurological Institute.

Neuronal/glioneuronal tumors are uncommon neoplasms of the CNS with frequent association with refractory epilepsy. Reports documenting the entire spectrum of neuronal/glioneuronal tumors are scarce in the literature. Zulch et al. from Germany in a large series reported that neuronal/glioneuronal tumors accounted for 0.4% (38/9000 cases) of all brain tumors, with similar incidence reported from Japan (0.4%), with higher incidence from Korea (2.1%). However, data from the Indian subcontinent are lacking. We reviewed 244 cases of neuronal/glioneuronal tumors of the CNS diagnosed over the last decade at our Institute and they constituted 0.86% of all CNS tumors (244/28061) received in that period. Mean age at presentation was 25.06 years (range: 1-75 years) with male preponderance (M:F = 1.54 : 1). The majority occurred in third decade (76 cases, 31.4%), with only few cases occurring beyond fifth decade (13 cases, 5.3%). Ganglioglioma/gangliocytoma (94 cases, 38.52%) was the most frequent followed by central neurocytoma (86 cases, 35.24%), paraganglioma (32 cases, 13.52%), dysembryoplastic neuroepithelial tumors (DNET) (21 cases, 8.6%), desmoplastic infantile astrocytoma/desmoplastic infantile ganglioglioma (DIA/DIG) (6 cases, 2.45%), papillary glioneuronal tumor (PGNT) (3 cases, 1.22%) and rosette-forming glioneuronal tumor (RGNT) (1 case, 0.4%). Association with seizures was noted in 40.95% of cases. Glioneuronal tumors are an expanding group of tumors with varying spectra of morphologic patterns and biological behavior. An improved understanding has direct clinical implications for optimizing current treatments and developing novel therapeutic approaches. Although most glioneuronal tumors carry a favorable prognosis, other factors such as inaccessibility to surgical resection and rarely, malignant transformation, make it difficult to accurately predict the biological behavior based on histopathology alone. Reliable prognostic markers remain to be defined.