[Recurrent petrosal tumor: meningioma or solitary fibrous tumor?]

Intracranial meningeal solitary fibrous tumors (SFT) originating from mesenchymal tissue are much less common than those with lesions of the visceral pleura or liver and were isolated as a nosological form only in 1996. These tumors are identical in clinical manifestations, MRI and light microscopy data to meningiomas. The pathognomonic difference of SFT, according to the 5th edition of the WHO classification, is the detection of overexpression of the protein encoded by the STAT6 gene. Estimation of other immunohistochemical markers is variable. At the same time, SFT has a tendency to more frequent recurrence and delayed malignancy. Transitional forms are possible. To form a clearer nosological outline of the SFT, it is necessary to accumulate clinical observations. A case of a giant meningioma of the posterior cranial fossa, which recurred 18 years after total removal at a 5-year annual control, is presented. Light microscopy of both primary and recurrent tumors revealed fibrous meningioma (WHO GI). Immunohistochemically revealed diffuse overexpression of CD34 and CD99. Determining the expression of the STAT6 protein was not technically possible. This case is regarded as a meningioma of the posterior surface of the pyramid of the temporal bone, growing into the cavity of the IV ventricle, with late recurrence without malignancy, with specific immunohistochemical profile.