Johannes Nowak MD, Presenter: Nothing to Disclose

Carolin Seidel, Abstract Co-Author: Nothing to Disclose

Frank Berg, Abstract Co-Author: Nothing to Disclose

Torsten Pietsch, Abstract Co-Author: Nothing to Disclose

Carsten Friedrich, Abstract Co-Author: Nothing to Disclose

Katja von Hoff, Abstract Co-Author: Nothing to Disclose

Stefan Rutkowski, Abstract Co-Author: Nothing to Disclose

Monika Warmuth-Metz, Abstract Co-Author: Nothing to Disclose

Ependymoblastoma (EBL) is a malignant, embryonal central nervous system (CNS) tumor of early childhood with a dismal prognosis. Categorized by the WHO as a subgroup of CNS-PNET (primitive neuroectodermal tumor), EBL is histologically defined by “ependymoblastic rosettes“. Due to its rarity, little is known about specific MRI characteristics of EBL. We first systematically analyze and discuss MRI features of EBL in a series of 22 consecutive patients.

All 22 EBL cases within this study were centrally reviewed for histopathology, MRI findings, and multimodal therapy. Patients were diagnosed between 2002 and 2013. For systematic analysis of initial MRI scans at diagnosis, we evaluated 25 standardized criteria for reference image evaluation of pediatric brain tumors. Image reading was performed by two neuroradiologists in consensus.

EBL are large tumors with well-defined tumor margins and iso- to hyperintense signal on T2WI. The majority of EBL were located supratentorially (16/22 patients), whereas 4 tumors were found infratentorially and 2 tumors occurred in the brainstem. Tumors showed diffusion restriction in all cases where DWI was provided. Surrounding edema was present in 9%, and cysts could be found in 50% of the EBL cases. Contrast enhancement was variable, with a tendency to mild or moderate enhancement. Subarachnoid spread is common in EBL, but can be absent initially. There was a male preponderance (1.75:1 ratio) for EBL in our cohort. Mean age at diagnosis was 2.1 years.

Imaging appearance of EBL seems to share features with other pediatric embryonal CNS tumors. However, future studies are needed to systematically compare MRI findings of EBL with other CNS-PNET and ependymoma, in order to delineate imaging criteria that might help distinguish these pediatric brain tumor entities. Since there is still an ongoing debate about the exact histopathological definition of EBL among neuropathologists, we contribute to this discussion with the first systematic analysis of imaging characteristics of EBL.

With this study, we add the largest case collection to the very limited published database of MRI findings in EBL, together with epidemiological data.

Nowak, J, Seidel, C, Berg, F, Pietsch, T, Friedrich, C, von Hoff, K, Rutkowski, S, Warmuth-Metz, M, MRI Characteristics of Ependymoblastoma: Results from 22 Centrally Reviewed Cases.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14004878.html