Pediatric extra-axial glioblastoma with bone invasion leading to a subcutaneous mass: A case report

Pediatric glioblastoma multiforme (p-GBM) is an exceptionally rare and aggressive brain tumor, with even fewer reported cases with radiographic and intraoperative characteristics that mimic those of extra-axial lesions, often posing a diagnostic challenge. Despite advancements in imaging technologies, the diagnosis of GBM can still be intricate, relying primarily on histopathological confirmation.

We present a unique case of a 15-year-old female who presented to our hospital with a new-onset focal-to-bilateral tonic-clonic seizure described as clonic movements of her left hemicorps; on clinical examination, a subcutaneous mass was evident in the right parietal region. Magnetic resonance imaging of the brain revealed a sizable extra-axial enhancing mass measuring 9 cm, located in the right parieto-occipital region with notable bone invasion. Moreover, the intraoperative findings revealed an extra-axial mass attached to the dura. Total en bloc resection was achieved. The histopathological analysis confirmed the diagnosis of glioblastoma multiforme. Subsequently, the patient underwent adjuvant radiotherapy in conjunction with temozolomide chemotherapy. Postoperatively, she exhibited clinical improvement and remained stable throughout the 6-month follow-up period.

We present the first case of extra-axial p-GBM in a young patient, which remarkably led to the destruction of the bone and finally resulted in a sizable parietal subcutaneous lesion in the absence of prior surgery or radiation.