Atypical teratoid/rhabdoid tumors and choroid plexus tumors: when genetics "surprise" pathology.

Atypical teratoid/rhabdoid tumor (ATRT) and choroid plexus tumors (CPT) represent, so far, 2 well defined types of CNS neoplasm on the basis of their histological features and clinical presentation (10). While CPTs are intraventricular epithelial tumors arising from choroid plexus epithelium, the cellular origin of ATRTs is still unknown. Inactivating mutations of the hSNF5/INI-1 gene located in the chromosomal region 22q11.2 are regarded as a crucial step in the molecular pathogenesis of ATRTs; the genetic changes associated with CPTs are largely unknown. However, the recent finding of inactivation of hSNF5/INI-1 in choroid plexus carcinomas and papillomas (9, 18) points to a closer relationship between these 2 entities. This is supported by the occurence of choroid plexus carcinomas (CPC) in the setting of families with rhabdoid predisposition syndrome (RPS), (19) caused by germ line inactivation of the INI1 gene.