[A new entity in WHO classification of tumors of the central nervous system--embryonic tumor with abundant neuropil and true rosettes: case report and review of literature].

Embryonic tumor with abundant neuropil and true rosettes (ETANTR) is a very aggressive rare tumor with unique histologic and molecular features occurring in very young children. At present approximately 80 cases of ETANTR have been documented in the literature since first description in 2000. We report seven patients with ETANTR below 4 years of age who underwent surgical resection in the Burdenko Neurosurgery Institute between 2005 and 2010. Four children have received different modality chemotherapy and radiotherapy and two patients were treated by chemotherapy alone. One child did not receive any adjuvant treatment. All children had local relapses, two of them were operated twice. A 2 year old girl underwent subtotal resection thrice. Histological examination showed that all tumors were composed of true multilayered rosettes admixed with large areas of paucicellular neuropil. By analysis of recurrences we have found that large areas of neuropil and number of true rosettes were lost and tumors acquired a resemblance to central nervous system primitive neuroectodermal tumors. In four cases frozen tumor material was available for array-based comparative genomic hybridization, which discovered trisomy of chromosome 2 and amplification at the 19q13.42 chromosome locus. Fluorescence in situ hybridization revealed amplification at the 19q13.42 chromosome locus in all cases.