Choroid plexus tumors (CPT) are rare tumors that begin in the ventricles of brain. Often, CPTs can block the flow of cerebrospinal fluid within the ventricles. Choroid plexus tumors can be benign or malignant. Subtypes of CPTs include: choroid plexus papilloma (CPP), atypical choroid plexus papilloma and choroid plexus carcinoma.