Clinicoradiological features of rosette-forming glioneuronal tumor (RGNT) of the fourth ventricle: report of four cases and literature review.

BACKGROUND: Rosette-forming glioneuronal tumor (RGNT) of the fourth ventricle is a recently characterized rare tumor entity. Despite benign histological features and a reported favorable postoperative course, there is still limited clinical experience with this tumor.
METHODS: Retrospective analysis of the clinical, radiological, and surgical data in four patients with RGNT was performed. Mean age at diagnosis was 35 years, and the median follow-up was 19 (range 2-30) months. The results were compared with the literature.
RESULTS: Patient 1 presented on an emergency basis due to intratumoral hemorrhage and tumor enlargement followed by life-threatening obstructive hydrocephalus. Patient 2 suffered from headaches and left-sided hemiparesthesia 6 months prior to surgery. Patient 3 developed headaches with nausea and vomiting, followed by left-sided tinnitus 1 year prior to surgery. In patient 4, RGNT was detected incidentally. No differentiating radiological characteristics were seen except for the presence of minute satellite lesions in two patients. Histopathological findings were distinct and showed their typical biphasic neurocytic and glial architecture. No progression/recurrence was seen in the postoperative course.
CONCLUSIONS: The spectrum of presenting symptoms of RGNT is wide, nonspecific, and typically depends on tumor size and extent. This tumor entity should be considered in the differential diagnosis of posterior fossa masses in order to avoid undue surgical aggressiveness.