Radiology

Abstract

INTRODUCTION: Pediatric CNS embryonal neoplasms represent a unique group of poorly differentiated malignant tumors with propensity to disseminate throughout the neuraxis and exhibit aggressive clinical behavior. They are typically classified as medulloblastoma, other CNS site PNET (e.g., pineoblastoma) and AT/RT. A novel PNET variant, ETANTR, has been reported in approximately 30 children worldwide. ETANTR appears to afflict young children, have a female predominance and occurs primarily in the cerebrum. The prognosis is dismal. We report atypical neuroimaging characteristics of two young children with ETANTR. REPORTS: A 5-year-old girl presented with headaches, ataxia and photophobia. MRI revealed a 5.1 x 7.4 x 6 cm mass seeming to arise from the right lateral ventricle. The mass showed T1 hypointensity, T2 hyperintensity and was isointense to gray matter on FLAIR sequences. DWI and ADC images showed patchy reduced diffusion. T1 post-contrast images showed enhancement of large vessels, but little parenchymal tumor enhancement. Gross total resection (GTR) was achieved, ETANTR was diagnosed and there was no evidence of neuraxis metastases. A 2-year-old boy presented with seizures. MRI revealed a 2.2 x 2.9 x 2.2 cm mass in the right frontal lobe parenchyma, showing the same characteristics as the first case, except for a thin, partial FLAIR-hyperintense rim, partial reduced diffusion, and post-contrast enhancement only of a few small vessels. GTR was achieved, ETANTR was diagnosed and there was no evidence of neuraxis metastases. CONCLUSIONS: ETANTR is now recognized as a distinct type of CNS embryonal tumor/PNET. It occurs in young children and carries a poor prognosis. The neuroimaging characteristics in the two reported cases here, namely FLAIR isointensity to gray matter and paucity of parenchymal tumor enhancement, are atypical of malignant embryonal tumors and should be considered as a factor in the neurodiagnostic differential diagnosis of children with newly discovered CNS tumors.