Long-term survival in a case of ETANTR with histological features of neuronal maturation after therapy.

Embryonal tumor with abundant neuropil and true rosettes (ETANTR) is a rare subtype of primitive neuroectodermal tumors and one of the most aggressive brain tumors in children. The neoplasm harbors a specific genetic alteration, amplification of the miRNA cluster C19MC at 19q13.42. We report a case of a 21-month-old boy with a mass in the left fronto-opercular region. The lesion was partially resected and pathology examination revealed an ETANTR with immunoreativity for LIN28A protein and amplification of the C19MC locus. The child received the PNET infant indications followed by high-dose thiotepa which resulted in a significant reduction of the mass. Subsequently, a second operation was carried out and the residual mass removed. Histology at this time showed a low-grade lesion composed of neuronal cells ranging from neurocytes to ganglion cells embedded in abundant neuropil with no immature embryonal component and multilayered rosettes. In addition to these features, a decrease in the number of nuclei with amplification of the C19MC locus was also observed. Thirty-one months after the second operation, the patient is alive and well. Such long-term survival could be explained by neuronal maturation induced by therapy associated with reduction of neoplastic cells with amplification of C19MC locus. This case suggests that the induction of differentiation may represent an optimal treatment strategy for very aggressive malignancies as ETANTR.