Clear cell ependymoma: a clinicopathologic and radiographic analysis of 10 patients.

BACKGROUND: Clear cell ependymoma (CCE) is an uncommon central nervous system tumor with a predilection for the supratentorial region in children. Histologically, it may mimic oligodendroglioma, central neurocytoma, hemangioblastoma, and renal cell carcinoma.

METHODS: The authors reviewed the clinical, radiographic, and pathologic features, therapy, and outcome in 10 children with CCE who were treated at St. Jude Children's Research Hospital (1984-2003). Fluorescence in situ hybridization (FISH) was performed using 1p/1q, 19p/19q, CEP18/DAL1, and bcr/NF2 probe pairs.

RESULTS: The median patient age at diagnosis was 7.5 years (range, 1-19 years). Tumors occurred supratentorially in 9 of 10 patients. All tumors had rounded nuclei with surrounding, clear halos and at least focal perivascular pseudorosettes. Seven tumors had anaplastic features. No deletions involving 1p, 19q, or NF2 were detected. The tumors from 5 of 7 patients, all with anaplasia, had losses of both CEP18 and DAL-1. Radiographically, all tumors were enhanced, and 9 tumors had associated cysts with enhancing walls. Seven patients underwent gross total resection, which was near total in one patient and subtotal in two patients. Five patients received immediate postoperative local radiotherapy. Three patients were diagnosed initially with pilocytic astrocytoma (one patient) and oligodendroglioma (two patients) and were observed. The progression-free survival and overall survival rates at 5 years were 34% +/- 20% and 75% +/- 19%, respectively. The median follow-up was 37 months (range, 5-239 months). Five patients developed local recurrence within a median of 9 months after diagnosis. Two patients developed extracranial soft tissue and lymph node metastases.

CONCLUSIONS: CCEs were found to have a predilection for extraneural metastases and early recurrence and demonstrate characteristic radiographic features, anaplastic histologic features, and chromosome 18 losses. The authors recommend resection followed by local radiotherapy as the treatment of choice in children.