Case report: Primary intracranial EWs/PNET in adults: Clinical experience and literature review.

Introduction: Adult primary intracranial Ewing sarcomas (EWs)/primitive neuroectodermal tumors (PNETs) are extremely rare, with only 30 patients published before us. The imaging features and treatment strategies of primary intracranial EWs/PNETs are unclear due to its rarity. The aim of this study was to investigate the clinical features, imaging findings, treatment, survival analysis, and prognosis of adult EWs/PNETs, and a systematic review was conducted based on the patient we treated and published literature. Case description: A 19-year-old male patient suffered from head pain due to an accidental fall on a motorcycle that occurred more than 10 days before going to the hospital, and underwent computed tomography (CT) examination; it was found that the left temporo-occipital fossa was occupied. Magnetic resonance imaging (MRI) was recommended to understand the nature of the lesion, and the result showed that it has a high probability of being a meningioma. He underwent surgical removal of the mass under general anesthesia, and surprisingly, postoperative pathology revealed EWs/PNET. The disease has a high degree of malignancy, and the patient developed multiple metastases throughout the body 5 years after surgery. Conclusion: Primary intracranial EWs/PNETs in adult patients are rare, of which imaging findings should be considered as one of the differential diagnoses of meningioma, hemangiopericytoma, and malignant triton tumor. Larger solid-cystic masses with septum-like enhancement may be relatively specific imaging findings of intracranial EWs/PNETs. The prognosis of primary adult intracranial EWs/PNETs is poor. Radical tumor resection combined with radiotherapy and chemotherapy is currently the main and possibly the most effective treatment method.