Embryonal tumor with abundant neuropil and true rosettes (ETANTR): report of a case with prominent neurocytic differentiation.

We report a case of a 2 year-old boy who initially presented with macrocephaly and severe global developmental delay. Imaging revealed a large left temporo-parietal mass that was lobulated, calcified, focally enhancing and partially cystic. A second surgery was required for tumor recurrence approximately one year later, and tissue from that resection proved to be diagnostic for an embryonal tumor with abundant neuropil and true rosettes (ETANTR). Only 12 cases of this rare pediatric embryonal tumor have been previously documented, and as of 2000, the WHO has not recognized ETANTR as a distinct entity (Kleihues P, Cavenee WK (2000) International agency for research on cancer: pathology and genetics of tumors of the nervous system. IARC Press, Lyon). As opposed to prior cases, our patient's tumor exhibited extensive neurocytic elements. Two recently described cases were examined via fluorescence in situ hybridization (FISH), with one demonstrating isochromosome 17q (i17q) and the second exhibiting polysomies of chromosomes 2, 8, 17 and 22 (Fuller C, Fouladi M, Gajjar A, Dalton J, Sanford RA, Helton KJ (2000) Am J Clin Pathol 126: 277-283). Via FISH analysis, we found normal dosages of chromosomes 2, 8 and 17. Our case expands the histopathologic spectrum of ETANTR, illustrating marked neuronal differentiation towards neurocytes. The lack of common PNET-associated FISH abnormalities in this case adds to the limited cytogenetic genetic data on this rare pediatric embryonal neoplasm.