Choroid Plexus Tumors

2023-04-03 Scott Ryall, PhD Affiliation

1.Brigham and Women's Hospital, Harvard Medical School, Boston , MA (USA)

Classification

Definition

Choroid plexus tumors (CPT) are rare tumors of the central nervous system (CNS) that originate from the choroid plexus epithelium. They are most common in the pediatric population, accounting for up to 20% of brain tumors diagnosed in children < 2 years old. ^1,2 Rare cases in adults have also been reported.^3,4 CPT typically arise in the ventricles and their primary site of occurrence varies with age; lateral ventricles (most often in the atrium) in children and the fourth ventricle or (rarely) the cerebellopontine angle in adults. ³
The World Health Organization (WHO) 2021 classification of CPT has remained largely unchanged from the 2016 version, although an emphasis on separating them from primary neuroepithelial tumors has been established. ^5,6 The WHO 2021 classifies CPT as choroid plexus papilloma (CPP; WHO Grade 1), atypical choroid plexus papilloma (aCPP; WHO Grade 2), and choroid plexus carcinoma (CPC; WHO Grade 3). This classification is based on histopathologic features, namely the number of mitotic figures within the specimen.

Choroid Plexus Tumors	Genetic Event(s)
Choroid Plexus Papilloma (CPP)	Cytogenetic technologies have identified hyperdiploidy in Choroid Plexus Papilloma (CPP) with frequent chromosomal gains including, but not limited to chromosomes 7, 8, 9, 11, 12, 18, and 20. ^7-10 Infrequent losses are most commonly observed in chromosomes 10 and 21. ^7-10 The pathogenic impact of these chromosomal alterations are, as of yet, not fully understood. TP53 mutations, including those qualifying as Li-Fraumeni syndrome OMIM:151623, are rare in CPP at approximately 10%. ^10,11 Other syndromic associations with CPP include Aicardi Syndrome OMIM:304050,¹² hypomelanosis of Ito OMIM:300337, ^13,14 and constitutional 9p duplication. ^15,16 DNA methylation analysis segregates Choroid Plexus Tumors into 3 distinct clusters of which CPP and Choroid Plexus Carcinoma CPC remain separate despite some overlap between CPP and atypical CPP ^17-19
Atypical Choroid Plexus Papilloma (aCPP)	The genetic features of atypical Choroid Plexus Papilloma (aCPP) mimic those seen in CPP and include hyperdiploidy with frequent chromosomal gains including, but not limited to chromosomes 7, 8, 9, 11, 12, 18, and 20 and losses in chromosomes 10 and 21. ^7-10 Likewise, rare TP53 mutations, some in the context of Li-Fraumeni syndrome, have been reported. ^10,11 DNA methylation analysis segregates Choroid Plexus Tumors into 3 distinct clusters of which aCPP and CPP display some overlap given their diagnostic similarities. ^17-19
Choroid Plexus Carcinoma (CPC)	Germline mutations in TP53 have been reported in up to 50% of Choroid Plexus Carcinoma (CPC). ^10,11 Further, the combination of the TP53 p.R72 variant and the MDM2 SNP309 polymorphism, two sequence variants known to confer TP53 dysfunction, have been shown in >90% of TP53 wildtype CPC implicating universal TP53 dysfunction. ¹¹ Elevated genomic instability in CPC has been detected using classic cytogenetic and array-based approaches ^8-10,20,21 and are related to the patient's age with, for example, pediatric CPC often showing hypodiploidy . ²¹ DNA methylation analysis classifies CPC as a distinct molecular classification unique to both CPP and aCPP. ^17-19

Article Bibliography

Reference Number	Pubmed ID	Last Year	Title	Authors
1	21970783	2012	Choroid plexus tumors in pediatric patients.	Ogiwara H et al
2	20809071	2011	Choroid plexus tumors in children less than 36 months: the Canadian Pediatric Brain Tumor Consortium (CPBTC) experience.	Lafay-Cousin L et al
3	26500797	2015	Case series of choroid plexus papilloma in children at uncommon locations and review of the literature.	Prasad GL et al
4	26161225	2015	Choroid plexus carcinoma in adults: an extremely rare case.	Ozdogan S et al
5	27157931	2016	The 2016 World Health Organization Classification of Tumors of the Central Nervous System: a summary.	Louis DN et al
6	34185076	2021	The 2021 WHO Classification of Tumors of the Central Nervous System: a summary.	Louis DN et al
7	7533531	1994	Chromosome aberrations in choroid plexus papillomas.	Donovan MJ et al
8	11891207	2002	Chromosomal imbalances in choroid plexus tumors.	Rickert CH et al
9	25336695	2015	Molecular characterization of choroid plexus tumors reveals novel clinically relevant subgroups.	Merino DM et al
10	25575132	2015	High-resolution genomic analysis does not qualify atypical plexus papilloma as a separate entity among choroid plexus tumors.	Japp AS et al

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External Links

Citation

Scott Ryall

Choroid Plexus Tumors

Atlas Genet Cytogenet Oncol Haematol. 2023-04-03

Online version: http://atlasgeneticsoncology.org/solid-tumor/209104