Gliosarcoma arising from a fibrillary astrocytoma

Area of Science:

• Neuro-oncology
• Cancer genetics
• Brain tumor pathology

Background:

• Fibrillary astrocytoma (World Health Organization [WHO] grade II) is a primary brain tumor.
• Gliosarcoma (WHO grade IV) is a rare and aggressive glioblastoma variant.
• Tumor progression can involve changes in histology and genetic alterations.

Observation:

• A 67-year-old woman initially diagnosed with fibrillary astrocytoma (WHO grade II) via stereotactic biopsy.
• Initial biopsy showed no loss of heterozygosity (LOH) on chromosomes 1p, 10q, and 19q.
• After chemotherapy but no radiotherapy, MRI revealed rapid tumor growth.
• A subsequent partial tumor removal revealed gliosarcoma (WHO grade IV).
• The gliosarcoma showed LOH on chromosomes 10q and 19q.

Findings:

• The patient experienced a rapid malignant transformation from WHO grade II astrocytoma to WHO grade IV gliosarcoma over five months.
• Genetic analysis revealed a shift in loss of heterozygosity patterns, with acquired LOH on 10q and 19q in the higher-grade tumor.
• Chemotherapy alone did not prevent tumor progression to a higher grade.

Implications:

• This case underscores the potential for rapid dedifferentiation in brain tumors.
• Acquisition of specific genetic alterations (LOH 10q, 19q) may correlate with malignant progression.
• Understanding these dynamic changes is crucial for refining treatment strategies in neuro-oncology.