Choroid plexus tumors in children: Significance of stromal invasion

OBJECTIVE: A group of choroid plexus tumors fit the cellular criteria for c horoid plexus papilloma (CPP) except for invasion into the adjacent parench yma, with associated loss of the normal villus architecture at the site of invasion. These tumors retain a benign cellular appearance. In the existing literature, it is unclear whether these tumors are classified as choroid p lexus carcinomas or as CPPs. In our experience, although evidence of invasi on is present, these tumors tend to exhibit benign behavior. We suggest tha t stromal invasion of this type remains consistent with a benign clinical c ourse, although surgical results may demonstrate higher morbidity rates, gi ven the invasive nature of the tumors. The failure to classify these tumors as CPPs may explain some of the variability in outcomes reported for vario us studies. METHODS: To study this question, clinical and histological data for childre n diagnosed with CPPs (either with or without stromal invasion) between 198 5 and 1995 were examined. Only cases with pre- and postoperative magnetic r esonance imaging data were included in the series. RESULTS: A total of 12 patients with CPPs were identified, with 4 tumors be ing notable for stromal invasion. After gross total tumor removal, none of the eight children with CPPs received adjuvant therapy at our institution; all are alive without evidence of tumor recurrence after surgical excision (mean, 108 mo). Of the four patients with stromal invasion, three underwent gross total resection. The one patient who underwent subtotal resection re ceived chemotherapy at another facility. All four of these patients are ali ve, after a mean of 100 months of follow-up monitoring. CONCLUSION: It is recommended that CPPs with a benign cellular appearance b ut with evidence of local parenchymal invasion and loss of the normal villu s architecture at the site of invasion be classified as CPPs. Patients with these tumors respond to surgical therapy alone, without the need for adjuv ant treatment.