Primary dura-based synovial sarcoma of the parafalcine region of brain.

Dura-based intracranial neoplasms include a wide range of primary and metastatic tumors, varying in their clinical, radiologic, morphologic, and immunophenotypic characteristics. At this anatomic location, sarcomas are rare, however, they exhibit close morphologic resemblances to meningioma. Herein we describe the third case of primary synovial sarcoma of the parafalcine region in a50-years-old female, who presented with left-sided hemiplegia. The radiologic survey revealed a 5.5cm×5.8cm contrast enhancing dura-based mass at the right parafalcine region with meningeal enhancement and edema in the surrounding areas. Morphologic evaluation exhibited a high-grade spindle cell neoplasm, with focal hemangiopericytomatous pattern. The tumor cells were diffusely immunoreactive for CD99, Bcl2, TLE-1, and vimentin. The Ki-67 proliferation index was 40%. Pancytokeratin was focally positive. Epithelial membrane antigen, progesterone receptor, CD34, S-100, and glial fibrillary acidic protein were negative. Fluorescence in situ hybridization confirmed tumor specific translocation t(X;18)(p11.2;q11.2). Hence, final diagnosis of synovial sarcoma was rendered. Primary meningeal synovial sarcoma should be considered in the differential of aggressive and high-grade dura-based tumors in view of their relative chemosensitivity and future prospect of a molecular target-based therapy. The index case highlights the importance of an extensive pathologic analysis of high-grade mesenchymal lesions of the meninges to arrive at a definitive diagnosis and differentiate such tumors from other usual dura-based tumors, which has important therapeutic and prognostic implications.