Myxoid Glioneuronal Tumours with PDGFRA p.K385 Mutations Causing Hydrocephalus and Successfully Treated with Neuroendoscopic Surgery: A Case Report and Literature Review.

Myxoid glioneuronal tumour (MGNT) is a new WHO classification of brain tumours and is defined as tumours with PDGFRA p.K385 mutations. MGNT has a predilection for the septum pellucidum, their clinical features have not yet been clarified because only a few reports exist. In this report, we present the case of a patient with an MGNT that was suitable for endoscopic resection. We discuss the clinical characteristics of MGNTs discovered during a literature review. A 19-year-old female presented with a worsening headache and a disturbance of consciousness. Head MRI revealed a mass lesion in the septum pellucidum and severe obstructive hydrocephalus. She underwent neuroendscopic surgery under general anaesthesia, and near total resection was achieved. Her symptoms improved immediately after surgery, and she was discharged without any morbidities. Pathological examination and genetic testing confirmed the diagnosis of an MGNT. A literature review revealed that 7 of 18 MGNTs developed in the septum pellucidum. Three patients had disseminated lesions at initial diagnosis, and one showed dissemination during the follow-up period. Among the 14 patients who underwent tumour resection surgery, 3 experienced recurrence or regrowth and required additional treatments. All 18 patients were alive at the last follow-up. An MGNT is a tumour that predominantly affects young people and is currently considered to have a good prognosis. However, close postoperative observation is needed because an MGNT often disseminates intracranially and/or into the spinal cord. In addition, we believe that MGNTs located in the septum pellucidum are good candidates for endoscopic resection.