Ependymoma: ultrastructural studies of two cases

Area of Science:

• Neuro-oncology
• Cellular Ultrastructure
• Neoplastic Pathology

Background:

• Ependymomas are tumors arising from ependymal cells, the cells lining the ventricles of the brain and the central canal of the spinal cord.
• Understanding ependymoma ultrastructure is crucial for accurate diagnosis and classification, particularly for differentiating subtypes and grades.
• Previous studies have characterized typical ependymoma ultrastructural features, but unusual findings can offer insights into cell differentiation and tumor biology.

Observation:

• Case 1 (Grade I, fourth ventricle ependymoma) exhibited intracytoplasmic vacuoles containing microrosettes with abnormal zonulae adherentiae.
• Case 2 (recurrent Grade III, third ventricle ependymoma) showed dense-core vesicles and parallel microtubule arrays in tumor cell processes within perivascular pseudorosettes.
• These observed ultrastructural features were not present in normal mammalian ependymal cells.

Findings:

• The unusual vacuoles in Case 1 suggest potential complex intracellular structures or degenerative processes.
• The dense-core vesicles and microtubule arrays in Case 2 are characteristic of ependymal tanycytes, a specialized ependymal cell type.
• These findings indicate potential tanycytic differentiation in the third ventricle ependymoma.

Implications:

• The presence of tanycyte-like structures in a third ventricle ependymoma suggests a possible link between tumor cell differentiation and the specific microenvironment of the third ventricle.
• Unusual ultrastructural findings can serve as diagnostic markers and may influence prognostic assessment of ependymomas.
• Further research into ependymoma heterogeneity and cell differentiation pathways could lead to novel therapeutic strategies.