Embryonal tumor with abundant neuropil and true rosettes (ETANTR): a new distinctive variety of pediatric PNET: a case-based update

Embryonal central nervous system (CNS) tumors are currently classified into three types: medulloblastoma, atypical rhabdoid/teratoid tumors, and primitive neuroectodermal tumor (PNET). A distinctive subtype of PNET called "embryonal tumor with abundant neuropil and true rosettes" (ETANTR) was reported in 2000. ETANTR is a recently described variety of PNET that combines microscopic features of neuroblastoma and ependymoblastoma, demonstrating areas of fine fibrillary neuropil intermingled with cellular zones and ependymoblastic rosettes. It has been suggested that this neoplasm should be considered as a separate entity. ETANTR is an eminently pediatric tumor that has been reported exclusively in children younger than 4 years. A 9-month-old girl underwent subtotal resection of a brainstem neoplasm. A 23-month-old girl was submitted to surgery for a frontoparietal tumor. In both instances, the histopathological diagnosis confirmed ETANTR. Both children were treated with chemotherapy and one with radiotherapy. Death in both patients occurred after a mean period of 10 months. By reporting these two new instances of ETANTR, we want to contribute to the knowledge of this highly malignant CNS embryonal neoplasm that occurs only in young children, given its present lethal prognosis, the scarcity of reported cases, and the lack of treatment guidelines.