PNET/ESFT of the cranial vault: a case report.

A case of peripheral PNET (PNET/ESFT) of the cranial vault is described. A 56-year-old woman showed a mass with a large cyst in the right temporal region, adherent to the meninges, which caused a left hemiparesis with headache and confusion. The mass was totally removed. The histological examination showed a dense proliferation of small elements, organized in lobules separated by reticulin septa. Many circumscribed necroses, vessels with a thick handcuff of reticulin, a diffuse mucous degeneration and abundant mitoses were present. The cells were positive for Vimentin and CD99. RT-PCR revealed the EWS/FLI1 fusion transcript of the t(11,22) (q24;q12) translocation. The patient presented is the oldest one of the rare cases of dura-based meningioma-mimicking pPNETs till now described. In line with the possible origin from peripheral nerves or roots of cauda equina of non-intracranial tumors, those of the vault may derive from peripheral sensory nerves of the dura. The differential diagnosis must be made with cPNETs which show a worse prognosis and both can benefit from a different chemotherapy.