A very rare primary choroid plexus carcinoma occurred in a 44-year-old male presenting with occipitalgia, nausea, and blurred vision. The tumor had progressed from a choroid plexus papilloma in the fourth ventricle which was totally removed 6 years previously. Lectin histochemistry might be useful for the differential diagnosis of primary choroid plexus neoplasms and other brain tumors such as secondary carcinoma.