LAUSR

BACKGROUND Intracranial Ewing sarcoma (ES) and peripheral primitive neuroectodermal tumors (pPNETs) are extremely rare and poorly differentiated neoplasms. Immunohistochemical and cytogenetic findings support the possibility of a unique nosologic entity. Primary intracranial localization of this tumor is extremely rare; a few cases are reported in the literature, with only some confirmed by genetic studies. CASE DESCRIPTION We report a 12-year-old patient with a sellar/suprasellar mass with intraventricular extension that in all its features mimicked a transinfundibular craniopharyngioma. The patient underwent complete resection of the lesion via an endoscopic endonasal transtuberculum approach 6 days after ventriculoperitoneal shunt for acute obstructive hydrocephalus. Histopathologic and genetic examination demonstrated ES/pPNET. The diagnosis was confirmed by detection of a rearrangement of the EWSR1 gene by fluorescent in situ hybridization and identification of the diagnostic t(11;22) translocation by reverse transcriptase polymerase chain reaction. The patient remained in complete clinical remission 12 months after tumor resection followed by adjuvant chemotherapy with no radiologic evidence of tumor recurrence. CONCLUSIONS To our knowledge, this is the first case of primary intrasellar/suprasellar-intraventricular ES/pPNET confirmed by molecular genetic analysis. Extensive investigations, including pathologic, immunohistochemical, and genetic studies, are needed for differentiation of these tumors from other, more common sellar/suprasellar tumors. Our case highlights that an interdisciplinary therapeutic approach is mandatory to guarantee a favorable outcome.