Diagnostic Challenges in Choroid Plexus Tumours

Area of Science:

• Neuro-oncology
• Pediatric oncology
• Pathology

Background:

• Choroid plexus tumours (CPTs) are rare neoplasms originating from the choroid plexus.
• They represent a small fraction of central nervous system tumours but are significant in infants.
• CPTs display heterogeneity and are classified into three WHO grades: papilloma (WHO grade 1), atypical papilloma (WHO grade 2), and carcinoma (WHO grade 3).

Purpose of the Study:

• To review the histological and molecular characteristics of choroid plexus tumours.
• To highlight diagnostic challenges, including histological mimics and grading difficulties.
• To emphasize the role of molecular findings in improving diagnostic accuracy and prognosis.

Main Methods:

• Review of existing literature on choroid plexus tumours.
• Analysis of histological features and WHO classification criteria.
• Integration of molecular data, including TERT promoter mutations, TP53 mutations, DNA methylation, and copy-number assessment.

Main Results:

• Choroid plexus papilloma (CPP) is benign with good prognosis post-resection.
• Atypical CPTs (aCPPs) have increased mitotic activity and recurrence risk, particularly with TERT promoter mutations in adults.
• Choroid plexus carcinoma (CPC) is highly malignant, with poor outcomes in TP53-mutant cases, often linked to Li-Fraumeni syndrome.
• Accurate grading can be challenging, especially in small biopsies or atypical cases.
• Molecular analyses aid in diagnostic accuracy and prognostication.

Conclusions:

• Accurate histological grading and molecular profiling are essential for diagnosing and managing choroid plexus tumours.
• Understanding diagnostic pitfalls and differential diagnoses is critical across all age groups.
• Integration of molecular data improves diagnostic precision and prognostic assessment for CPTs.