Congenital ependymoblastoma arising in the sacrococcygeal soft tissue: a case study.

Ependymoblastomas are distinct embryonal tumors of the central nervous system reported only rarely in the literature. Most examples arise in young children under the age of 2 years, in the supratentorial compartment, and may or may not be related to the ventricular system. We report the case of a one-day-old infant who presented with a 6.4 x 5.6 x 3.5 cm ruptured buttock mass. Ultrasound demonstrated a solid mass at the base of the spine that displaced the bladder anteriorly with resultant hydronephrosis. Magnetic resonance images confirmed the presence of a solid mass surrounding the lower sacrum with an internal component partially encircling and deviating the rectum. Histopathological evaluation confirmed the diagnosis of ependymoblastoma. Of note, immunohistochemical analysis revealed diffuse staining with vimentin and patchy expression of synaptophysin, glial fibrillary acidic protein, neurofilament proteins, neuron-specific enolase, CD99 and nestin. On the 42nd day of life, chemotherapy was initiated with a modified Children's Oncology Group (COG) AGCT-01P1 (cyclophosphamide, cisplatin, 70% etoposide, no bleomycin) regimen. The authors describe their experience and review the literature, emphasizing that ependymoblastomas should be considered in the differential diagnosis of sacral masses in the newborn.