Gliosarcoma with osteosarcomatous component: A case report and short review illustration.

Gliosarcoma (GS) represents a rare variant of glioblastoma in the central nervous system, characterized by biphasic histopathological features of gliomatous and sarcomatous components. Here, we present an unusual case of GS, which also demonstrated osteosarcomatous differentiation. A 65-year-old female patient underwent gross total resection (GTR) of the right temporal lobe lesion. Subsequently received 60 Gy external beam radiation therapy and chemotherapy. Postoperative histopathological analysis indicated that the sarcomatous portion of the typical fibrosarcoma pattern mingled with areas of osteoid structure. The molecular pathological analysis demonstrated IDH1/2 wild-type and MGMT promoter island methylated phenotype. Target Enrichment Sequencing (TES) was performed on the gliomatous and sarcomatous components of the tumor tissues. TERT promoter, RB1, NF1, TP53 mutations and copy number variations (CNVs) on chromosome 7, 10q, 11q, 12, 13, 17 and 22 were observed in gliomatous and fibro-sarcomatous mixed tumor tissue; While we found TERT promoter, RB1, TP53 mutations and CNVs on chromosome 2q, 3q, 7, 8, 9, 10, 11, 12, 13, 15, 16, 17, 18, 19 and 22 in osteosarcomatous component. Noteworthy, EGFR amplification was not observed in both gliomatous/fibro-sarcomatous and osteosarcomatous components. Integrated with histopathology, molecular pathology, and genomic alteration analysis, we report a case of GS with an extremely rare histopathologic phenotype of osteosarcomatous differentiation, who also suffered lung multi-metastases. Additionally, synthesizing the literature review, our study of this unusual differentiation of GS into osteosarcoma may provide novel insight into the natural history of GS.