Spinal cord gliosarcoma with rhabdomyoblastic differentiation: a case report.

: Very few cases of gliosarcoma (GS) in the spinal cord with or without rhabdomyoblastic differentiation have been reported at young ages, leading to limited information on the clinical, pathological and prognosis of this type of tumors. We report a case of GS with rhabdomyoblastic differentiation in a 6-year-old girl in C1-C6 level spinal cord. This is, to the best of our knowledge, the first report of GS with rhabdomyoblastic differentiation primarily developed in spinal cord at such a young age. Histologically, GS is composed of both glioblastoma components and malignant mesenchymal components. In the present case, the mesenchymal portion displayed a typical pattern of rhabdoid morphology. The rhabdomyoblastic-differentiated cells were confirmed by desmin, MyoD1, myogenin and Vimentin immunopositivity. Loss of PTEN (phosphatase and tensin homolog) and amplification of EGFR (epidermal growth factor receptor) were not detected in both parts of GS (glioblastoma component and rhabdomyosarcoma component). Interestingly, in this case rhabdomyoblastic-differentiated cells (rhabdomyosarcoma component) were focally negative for integrase interaction 1 (INI-1) protein and glial cells (glioblastoma component) were positive, and monosomy 22 in the former and absence in the latter. The patient only received low-dose radiotherapy and survived only 6 months after diagnosis. GSs with rhabdomyoblastic differentiation have a worse prognosis than common GSs and high-dose radiotherapy is suggested to considerer.