Pediatric rosette-forming glioneuronal tumor of the septum pellucidum.

Rosette-forming glioneuronal tumor (RGNT) is a rare tumor entity which has been reported mainly occurring in the fourth ventricle. It has been described as a benign lesion with limited extension into surrounding structures, including the cerebellar vermis, midbrain, and cerebral aqueduct. More recently, few cases involving also other midline structures have been documented as well. Here, we report about diagnosis and treatment of RGNT in the septum pellucidum in a pediatric patient which has not been described previously. A 7-year-old boy had a 3-week history of headache. Magnetic resonance imaging showed a solid mass in the septum pellucidum accompanied by hydrocephalus. The tumor was resected via a transcortical approach. Histological examination revealed the typical findings of a RGNT. At 2-year follow-up, there was no tumor recurrence, and clinical outcome was unremarkable. RGNT has to be considered in the differential diagnosis of pediatric midline tumors also outside of the fourth ventricle. Surgical resection is the first-line therapy which may result in beneficial outcome in the long term. The role of adjuvant therapy needs further definition since due to the rarity of this tumor entity, available data is very limited.