Stereotactic biopsy done for clarifiying a diagnostic imaging in brainstem tumors is important in obtaining a definitive diagnosis with a low rate of complications.

A case of a cerebral malignant triton tumor in a 3-year-old boy with a 2-month history of frontal headache and no clinical evidence of neurofibromatosis is reported. The computed tomography (CT) scan showed a large, irregular tumor in the right parietooccipital lobe. A partial surgical resection was performed. Histologically, the tumor was highly cellular and consisted of spindle cells with hyperchromatic and pleomorphic nuclei. Focally, neoplastic cells with rhabdomyoblastic features were found. The immunohistochemical study showed that tumor cells were positive for S-100 protein and CD57, and the rhabdomyoblasts expressed desmin, Myo-D1, and myoglobin. During the postoperative period, a massive intraparenchymal hemorrhage was identified and surgical drainage was performed. The patient worsened and died 10 days after the first surgery. Postmortem study was not authorized. Six cases of cerebral malignant nerve sheath tumor have been described; however, primary intraparenchymal malignant triton tumor has not been previously described.

We report a 3-year-6-month-old boy with chordoid meningioma in the foramen magnum. Chordoid meningioma represents between 0.5 and 1.0% of all meningiomas, and it is frequently located in the supratentorial region. The patient started with an episode of instability, falls, and headache; after which, he developed cuadriparesis, cervical pain, and neck stiffness, which slightly improved after medical treatment, so he was referred to our hospital. Physical examination revealed left hemiparesis and cervical muscle spasm with left torticollis. Magnetic resonance imaging (MRI) demonstrated an intradural-extramedullary well-circumscribed, homogeneous enhancing mass, in the anterior part of the foramen magnum with cervical extension. The operative technique was the extreme-lateral craniocervical retrocondylar approach with total removal and dural coagulation. Histopathological examination demonstrated a chordoid meningioma, with meningotelial basophilic mucoid chordoma-like component in 80% of the tissue. The immunohistochemical stains were positive to epithelial membrane antigen, vimentin, and S-100 protein. At 10 months follow-up, the patient showed improvement in his neurological deficit with physical rehabilitation, and motor response in his extremities are now normal; neck stiffness with cervical spasm disappeared postoperatively. MRI showed no residual tumor. To our knowledge, this is the first report of a chordoid meningioma on the foramen magnum in a child.

The only favorable prognostic pattern was the supratentorial presentation. Radiotherapy and chemotherapy did not alter the outcome.