Gliosarcoma arising in oligodendroglial tumors ("oligosarcoma"): a clinicopathologic study

Area of Science:

• Neuro-oncology
• Surgical pathology
• Molecular pathology

Background:

• Gliosarcomas are rare biphasic tumors with glial and sarcomatous elements.
• Examples of gliosarcoma incorporating oligodendroglial components are exceptionally infrequent in medical literature.

Observation:

• This study identified seven patients diagnosed with oligodendroglial tumors exhibiting a sarcomatous component.
• The patients' mean age at diagnosis was 48 years, with tumor grades ranging from II to III.
• The sarcomatous component, comprising fibrosarcoma, leiomyosarcoma, or myogenic sarcoma, typically emerged during tumor recurrence or progression.

Findings:

• Immunohistochemistry confirmed glial markers (GFAP, S-100) in the glial component and sarcomatous markers (SMA, CD34, S-100, EMA) in the sarcomatous component.
• Fluorescence in situ hybridization (FISH) for 1p/19q codeletion was performed on both tumor regions.
• Five cases showed 1p/19q codeletion, with three cases exhibiting codeletion in both glial and sarcomatous elements.

Implications:

• The frequent 1p/19q codeletion in both components supports the hypothesis of metaplasia, where the sarcomatous element arises from the glial component.
• This finding contributes to understanding the pathogenesis of gliosarcomas, particularly those with oligodendroglial features.
• Further research into the molecular mechanisms underlying metaplasia in gliosarcomas is warranted.