The efficacy of a biopsy of intrinsic brainstem lesions for decision making of the treatments

The diagnosis of diffuse intrinsic pontine gliomas (DIPGs) has been generally made mainly by magnetic resonance imaging (MRI) and clinical course. However, the accuracy of MRI-based diagnosis has not been fully confirmed yet. Our aim was to review efficacy of biopsy for decision making of the treatments.

We retrospectively analyzed pediatric patients undergoing biopsy for intrinsic brainstem lesions which were considered atypical for DIPGs by MRI findings. The lesion was evaluated atypical when it extended beyond the pons or it had a well-margined localized enhancing portion.

Seven patients underwent biopsy. Preoperative MRI revealed a lesion extending beyond the pons in five patients and a focal enhancing lesion in four. Two patients had both of these. Open biopsy was performed via midline suboccipital approach in six patients and retrosigmoid approach in one. No intraoperative complications were observed. Histopathological examination revealed diffuse brainstem glioma in five patients, primitive neuroectodermal tumor (PNET) in one, and pilocytic astrocytoma in one. In the case with PNET, chemotherapy and radiotherapy were effective and the patient had been stable for 12 months without recurrence. The patient with pilocytic astrocytoma did not undergo radiotherapy and has been stable without regrowth of the tumor for 9 months.

Open biopsy of intrinsic brainstem lesions is considered to be safe and effective for selecting an appropriate course of therapy. Patients with intrinsic pontine lesions which extend beyond the pons or with localized enhancing portion seem to be benefited from the biopsy.