Posterior fossa ependymoblastoma diagnosed in the second month of life: uneventful 12 years survival after gross total resection followed by chemotherapy

This 2-month-old boy presented with a tense fontanelle, abnormal head growth, episodes
of vomiting, and “sunset” gaze.

Radiographic findings An MRI revealed pronounced supratentorial hydrocephalus and a partially contrast
enhancing right-sided posterior fossa tumor with downward herniation through the foramen
magnum and lateral displacement of the brain stem (Fig. 1).

Fig. 1. MRI scans disclose a partially contrast enhancing tumor to the right in the posterior
fossa with marked displacement of the brain stem to the left. a sagittal, b axial and c coronal scans.

Operation Intraoperative external drainage of the cerebrospinal fluid (CSF) was established
to control the intracranial pressure (ICP). A suboccipital craniotomy was performed
in the mid-line. The tumor was microsurgically excised via the fourth ventricle to
gross-total resection (GTR) of the tumor. The external drainage was terminated as
CSF flow through the Sylvian aqueduct had been observed. Postoperative MRI scans performed
in the same anesthetical procedure as the surgery confirmed the GTR (Fig. 2).

Fig. 2. Immediate postoperative MRI scans; a sagittal, b axial, white line demonstrating gross total resection.

The histological examination revealed a malignant small cell tumor with several true multilayered rosettes (Fig. 3a). The rosettes were postitive for vimentin (Fig. 3b), but negative for GFAP (Fig. 3c) and synaptophysin. The tumor was also focally positive for cytokeratin. The Ki-67
labelling index was about 90% in the most cellular areas (Fig. 3d). The tumor was diagnosed as an ependymoblastoma.

Fig. 3. A PNET-like tumor with true rosettes is seen in the HE-stained section (a). The true rosettes are positive for vimentin (b) and negative for GFAP (c). The Ki-67 labelling index is about 90% (d).

The biopsy has been re-examined by an experienced neuropathologist with the same conclusion.

Postoperative course and further treatment

Signs of persistent hydrocephalus reappeared after 3 days, and the patient underwent
an endoscopic 3rd ventriculocisternostomy. This procedure did not suffice and a ventriculoperitoneal
CSF-shunt had to be inserted after 2 weeks. After careful consideration the boy was
given chemotherapy according to the MET-HIT 2000-BIS4 protocol during the following
40 weeks. He had several episodes with serious infections, including shunt infection.
Following completion of the chemotherapy and infection controls, a new CSF shunt,
now ventriculoatrial, was implanted, 14 months after the tumor resection.

Serial follow-up MRI scans have demonstrated relative normalization in the posterior
fossa (Fig. 4), without any signs of recurrent neoplastic disease, as well as stable ventriculoatrial
shunt function.

Fig. 4. Late follow-up scans after 11 years. Normalisation in the posterior fossa, without
signs of residual or recurrent disease.

Today, this boy is 12 years and he follows a normal school program with some assistance
(5 h special teaching a week).

He has minor balance problems, but is playing soccer and he is also doing cross-country
skiing.