Gliosarcomas arising from the pineal gland region: uncommon localization and rare tumors.

Gliosarcomas are a variant of glioblastomas and present a biphasic pattern, with coexisting glial and mesenchymal components. In this study, two unusual cases are presented. Case 1 is a 52-year-old woman with a headache and memory disturbance for a month. Case 2 is an 18-year-old man with a headache lasting two weeks. In both cases, an MRI revealed enhancing T1-low to iso, T2-iso to high intensity lesions in the pineal gland region. Histologically, in case 1, the tumor showed spindle cell proliferation with disorganized fascicles and cellular pleomorphism. Tumor cells variously exhibited oncocytic transformation. Immunohistochemically, most of the spindle tumor cells were positive for myoglobin and desmin. Some of the tumor cells were positive for GFAP and S-100 protein. On the other hand, all tumor cells were positive for CD133, Musashi1, and SOX-2 which are the markers of neural stem cells. In case 2, the tumor showed monotonous proliferation of short spindle cells with disorganized fascicles and cellular atypism. The morphological distinction between glial and mesenchymal components was not apparent. Immunohistochemically, most of the spindle tumor cells were positive for desmin. Glial tumor cells that were dispersed within the sarcoma as single cells were positive for GFAP. In addition, all tumor cells were positive for CD133, Musashi1 and SOX-2. Based on these microscopic appearances, and immunohistochemical findings, these cases were diagnosed as gliosarcomas arising from the pineal gland region. These results also indicated that pluripotential cancer stem cells differentiated into glial and muscle cell lines at the time of tumor growth. In a survey of previous publications on gliosarcoma arising from the pineal gland, these cases are the second and third reports found in English scientific writings.