[A case of metastatic choroid plexus tumor from cholangiocellular carcinoma].

Metastatic intraventricular tumor located in the choroid plexus is very rare. Only a few cases have been reported in the past. According to past reports, these tumors originated from lung, colon, and so on, but not from the bile duct. This is the first case report of choroid plexus metastasis from cholangiocellular carcinoma. A 57-year-old woman who had a history of cholagiocellular carcinoma, demonstrated intraventricular tumor. Although sufficient examination was performed, the tumor was difficult to diagnose as being a metastatic tumor or a choroid plexus carcinoma. Because of this, we performed endoscopic biopsy of the intraventricular tumor. However intraoperative findings were not helpful in distinguishing metastatic tumor and choroid plexus carcinoma. Postoperatively, histological examination was performed. However it was still difficult to differentiate this rare tumor from choroid plexus carcinoma by only hematoxylin and eosin stain. For further examination, Ber EP-4 stain was performed. Ber EP-4 showed strongly positive which indicates metastatic tumor. This method led us to make an appropriate diagnosis of this extremely rare tumor. We considered that in order to diagnose this rare tumor, appropriate histopathological examination, including immunohistopathological examination should be performed.