A mixed choroid plexus papilloma and ependymoma

Area of Science:

• Neuro-oncology
• Pediatric Pathology
• Surgical Neurology

Background:

• Choroid plexus papillomas (CPPs) and ependymomas are distinct intraventricular tumors.
• Mixed tumors involving these lineages are exceedingly rare.
• Cartilaginous differentiation in such mixed tumors has not been previously documented.

Observation:

• A 5-year-old girl presented with fever and right lower limb numbness.
• MRI revealed a heterogeneously enhancing mass in the left lateral ventricle.
• Histopathology showed intermixed CPP and low-grade papillary ependymoma-like areas with cartilaginous islands and psammoma bodies.

Findings:

• A novel mixed choroid plexus papilloma and ependymoma with cartilaginous differentiation was identified.
• Direct transition between CPP and ependymoma components was observed.
• No high-grade features were present in the tumor.

Implications:

• This case expands the histopathological spectrum of intraventricular brain tumors.
• Understanding the pathogenesis of such mixed tumors may inform future classification and treatment.
• Highlights the importance of comprehensive histopathological and immunohistochemical analysis in rare neoplasms.