Extracranial extra-CNS spread of embryonal tumor with multilayered rosettes (ETMR): case series and systematic review

Embryonal tumors with multilayered rosettes (ETMR) is a rare variant of embryonal tumor of infancy with nearly 200 cases reported in the literature. Leptomeningeal spread of this tumor is well known; however, extracranial metastasis has been sparsely reported in the literature.

Our study was divided into two sections: (1) We conducted a retrospective review of our patient series of ETMR and screened for patients with evidence of ETMR over the last 10 years 2007-2017 at a single tertiary referral pediatric hospital, and (2) we conducted a systematic review according to PRISMA guidelines of all reported cases of ETMR to determine the incidence of extracranial metastasis and treatment paradigms.

Here we report three cases of extracranial non-CNS spread of ETMR and conduct a systematic review of ETMR to improve our understanding of ETMR metastases and treatment paradigms. In our systematic review (n = 204), median overall survival was less than 1 year with 44.1% children surviving over 1 year. Previously, only five cases of extracranial metastasis of ETMR have been reported.

Our case series (n = 3) and review demonstrate that these tumors may behave like soft tissue sarcomas and may be susceptible to tumor seeding through surgical manipulation or by CSF (ventriculoperitoneal shunt). Surgery for tumor recurrence may offer an improved local disease control, but preventative measures such as meticulous surgical resection may be necessary to reduce intraoperative contamination.