Choroid plexus tumors are rare intraventricular papillary
neoplasms derived from choroid plexus epithelium, which account for only between 0.4-0.6% of all intracranial and 2-3% of pediatric
neoplasms. Plexus
papillomas outnumber choroid plexus
carcinomas by a ratio of 5:1 and around 80% of choroid plexus
carcinomas arise in children. Plexus
tumors are most common in the lateral and fourth ventricles; while 80% of lateral ventricle
tumors present in children, fourth ventricle
tumors are evenly distributed in all age groups. Clinically,
choroid plexus tumors tend to cause
hydrocephalus and increased intracranial pressure. Histologically,
choroid plexus papillomas correspond to WHO grade I, choroid plexus
carcinomas to WHO grade III. Immunohistochemically, cytokeratins and
vimentin are expressed by virtually all
choroid plexus papillomas and most choroid plexus
carcinomas while
transthyretin and
S-100 protein are present in 80-90% of cases, less frequently, though, in choroid plexus
carcinomas.
Glial fibrillary acidic protein can be found focally in about 25-55% of
choroid plexus papillomas and 20% of choroid plexus
carcinomas. The mean Ki67/MIB1 labeling index for
choroid plexus papillomas is 1.9%, for choroid plexus
carcinomas 13. 8%.
Choroid plexus papillomas typically show hyperdiploidy with gains particularly on chromosomes 7, 9, 12, 15, 17, and 18 while one
choroid plexus carcinoma showed rearrangements of chromosomes 7p11-12, 9q11-12, 15q22, and 19q13.4.
Choroid plexus papillomas can usually be cured by surgery alone with a 5-year survival rate of up to 100% with occasional recurrences while choroid plexus
carcinomas grow more rapidly and have a less favorable outcome with a 5-year survival rate of 26-40%.