Rosette-forming glioneuronal tumour of the fourth ventricle: report of a case with clinical and surgical implications.

A 32-year-old woman presented with a 2-month history of episodic headache, cervical pain and neck rigidity. Neurological examination showed a moderate dysmetria. Magnetic resonance imaging (MRI) revealed a mass occupying the fourth ventricle. The patient underwent median sub-occipital craniotomy with total excision of the lesion well demarcated except for a portion infiltrating the right side of the IV ventricle wall. In the post-operative course the patient developed VI and VII right cranial nerves palsy and worsening of dysmetria. MRI confirmed the complete removal of the tumour without signs of recurrence. The pathological diagnosis was rosette forming glio-neuronal tumour (RGNT). At present this is the 13th RGNT reported in literature. These lesions are considered low-grade tumours (WHO I). Nevertheless, the case here reported, like in 6 of the 12 cases in literature, developed disabling post-operative deficits. To establish the therapeutic choice long-term follow-up studies are needed.