This article includes discussion of choroid plexus tumors of childhood, choroid plexus carcinomas, choroid plexus papillomas, and atypical choroid plexus papilloma. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.
Choroid plexus tumors of childhood are a relatively rare form of childhood brain cancer, comprising only 1% to 2% of all types of tumors that occur in patients younger than 18 years of age. Both choroid plexus papillomas and carcinomas can occur. Treatment of choice for both lesions is gross total resection. Patients with choroid plexus papillomas who have undergone complete resection rarely need alternative forms of adjuvant treatment. For patients with choroid plexus carcinomas, the need for adjuvant therapy following a gross total resection is unclear. Both radiotherapy and chemotherapy have shown questionable benefits for patients with subtotally resected choroid carcinomas. In this article, the author discusses some of the controversies in management and the genetic implications of a diagnosis of choroid plexus tumors.
• Choroid plexus tumors, although relatively rare, do make up a significant component of central nervous system tumors occurring in the first year of life.
• Separation of choroid plexus papillomas from atypical choroid plexus papillomas and atypical lesions from carcinomas is subjective, and the clinical course of atypical choroid plexus papillomas is less well characterized compared to other choroid tumor types.
• Degree of surgical resection is likely the single most important factor in determining outcome for all types of choroid plexus tumors.
Historical note and terminology
Choroid plexus tumors of childhood are a rare form of childhood neoplasm, constituting no more than 2% of all childhood primary central nervous system tumors (45). Although other types of central nervous system tumors may arise in the choroid plexus, the vast majority of childhood choroid plexus tumors are either papillomas or carcinomas (25). In Kernohan and Fletcher-Kernohan's 1937 study of 109 cases of ependymoma, choroid plexus papillomas were classified as a subvariety of ependymoma (30). This type of classification was widely used as late as the 1970s. In the most recent World Health Organization classification of tumors of the central nervous system, choroid plexus tumors are considered a distinct variety of neuroepithelial tumor and are subclassified as choroid plexus papillomas (Gr I), atypical choroid plexus papillomas (Gr II), or choroid plexus carcinomas (Gr III). Papillomas that are well-differentiated are relatively easy to categorize; however, some papillomas have increased cellularity, nuclear pleomorphism, and increased mitotic activity and may be classified as atypical choroid plexus papillomas (40). The updated WHO classification of tumors of the central nervous system continues the same classification (41).