Symptomatic subependymomas of the ventricles. Review of twenty consecutive cases.

BACKGROUND AND
PURPOSE: Intraventricular subependymomas are rare benign tumors, which are often misdiagnosed as ependymomas. To review the clinicopathological features of subependymomas. PATIENT SELECTION AND METHODS: Retrospective clinical analysis of intraventricular subependymomas and systematic review of histological slides operated on at our center between 1985 and 2005.
RESULTS: Twenty subependymomas presented at the median age of 50 years (range 19-77). Two (10%) were found in the third, three (15%) in the forth, and 15 in the lateral ventricles. There was male preponderance (12 vs. 8). Ataxia (n=13) and papilledema (n=7) were the most common clinical presentations. Fifteen patients underwent gross total resection, and five had subtotal resection. None of the cases showed mitotic figures, vascular endothelial proliferation or necrosis. Cell proliferation marker MIB-1 activity (percentage of positive staining tumor cells) ranged from 0 to 1.4% (mean 0.3). Two cases were treated with preoperative radiation therapy (50 Gy) before the CT era, three other patients received postoperative radiation therapy for tumors originally diagnosed histologically as low grade ependymomas. Three patients (15%) died of surgical complication between one and three months postoperatively, and three patients died of unrelated causes in eight, 26 and 110 months. Fifteen patients were alive without evidence of tumor recurrence at a median follow-up time of 10 years.
CONCLUSION: Subependymomas are low-grade lesions and patients do well without adjuvant radiotherapy. Small samples from more cellular areas may be confused with low grade ependymomas, and unnecessary radiotherapy may follow. Recurrences, rapid growth rates should warrant histological review, as hypocellular areas of ependymomas may also be a source of confusion.