Characterization of morphologically benign biologically aggressive meningiomas.

Area of Science:

• Neuro-oncology
• Tumor biology
• Pathology

Background:

• Meningiomas are classified into three World Health Organization (WHO) grades.
• While Grade I meningiomas are typically benign, some exhibit aggressive behavior.
• Identifying aggressive subtypes is crucial for patient management.

Purpose of the Study:

• To assess proliferation index (Ki-67) and p53 expression in meningiomas.
• To correlate these markers with histological grade and clinical outcomes.
• To identify aggressive meningiomas that may not be apparent from histology alone.

Main Methods:

• Retrospective analysis of 123 meningioma cases diagnosed between 2000 and 2007.
• Regrading of tumors based on WHO 2000 criteria.
• Immunohistochemical staining for Ki-67 antigen and p53 protein in 68 selected cases.

Main Results:

• Mean Ki-67 labeling index (LI) increased with tumor grade (3.8% for Grade I, 13.7% for Grade II, 19.4% for Grade III).
• Mean p53 expression also increased with grade (15.5% for Grade I, 57% for Grade II, 60.8% for Grade III).
• Recurrent meningiomas (all WHO Grade I) showed high Ki-67 LI (8.6%) and p53 expression (62.5%).

Conclusions:

• Ki-67 and p53 expression are valuable markers for identifying biologically aggressive meningiomas.
• These markers, combined with histopathology, can detect aggressive tumors that appear benign.
• This approach aids in predicting meningioma behavior and guiding treatment decisions.