Clear cells are associated with proliferative activity in ependymoma: a quantitative study

Area of Science:

• Neuro-oncology
• Tumor pathology
• Cancer biology

Background:

• Ependymomas are classified as WHO Grade II or III (anaplastic).
• Clear cell ependymoma (WHO Grade III) features clear cell proliferation, but clear cells also appear in conventional ependymomas.
• The prognostic significance of clear cells in ependymomas requires further elucidation.

Purpose of the Study:

• To investigate the direct relationship between the presence of clear cells and proliferative activity in ependymomas.
• To determine if clear cells are an independent prognostic factor in ependymoma diagnosis.

Main Methods:

• Studied 14 ependymomas (6 Grade II, 8 Grade III) containing clear cells.
• Utilized hematoxylin and eosin (H&E) staining, PHH3 (mitosis marker), and MIB-1 (Ki-67 antibody) immunostaining.
• Assessed necrosis, microvascular proliferation, clear cell grade (I-III), mitotic counts, and MIB-1 index.

Main Results:

• Necrosis and microvascular proliferation were observed regardless of clear cell grade.
• A higher abundance of clear cells was significantly associated with increased proliferative activity (mitotic count and MIB-1 index).

Conclusions:

• Clear cells in ependymomas are linked to higher proliferative activity.
• Clear cells may serve as an independent prognostic factor, distinct from WHO grade, necrosis, or microvascular proliferation.
• Evaluating clear cells is important for ependymoma diagnosis, irrespective of the 'clear cell ependymoma' subtype.