Malignant acoustic schwannoma

Area of Science:

• Neurosurgery
• Oncology
• Pathology

Background:

• Schwann cell tumors typically arise in the peripheral nervous system.
• Pleomorphic variants are rare and can exhibit aggressive behavior.

Observation:

• A 40-year-old man presented with a cerebellopontine angle tumor without neurofibromatosis stigmata.
• Histopathology revealed multinucleated giant cells, pleomorphism, and S100 protein immunoreactivity.
• Tumor recurred rapidly after initial resection, showing similar histology but altered flow cytometry findings.

Findings:

• The tumor exhibited extreme pleomorphism, tripolar mitoses, and aneuploidy, suggesting malignancy.
• Post-resection, flow cytometry revealed a double aneuploid population with increased tetraploid S-phase nuclei.
• Radiotherapy halted initial regrowth but did not prevent subsequent metastatic spread.

Implications:

• This case underscores the potential for aggressive behavior and metastasis in pleomorphic Schwann cell tumors.
• Advanced flow cytometry aids in assessing tumor ploidy and malignancy.
• Multimodal treatment strategies may be necessary for managing such rare, aggressive neoplasms.