Abstract
RATIONALE: Glioblastoma (GBM) is the most common primary malignant intracranial tumor in adults. GBMs with primitive neuronal components (GBM-PNC) represent a rare subtype of GBM, accounting for 0.5% of cases, often characterized by cerebrospinal fluid (CSF) dissemination and extracranial metastasis (ECM). Among the primitive neuronal components (PNC), MYC gene amplification is found in 43% of cases. Once diagnosed, treatment becomes extremely challenging; therefore, early identification and timely intervention are crucial. PATIENT CONCERNS: A 60-year-old male presented with a 5-day history of headache and limb weakness. He had no prior neurological disorders and no family history of brain tumors. DIAGNOSES: Magnetic resonance imaging of the head revealed a heterogeneously enhancing mass adjacent to the right lateral ventricle. Although postoperative immunohistochemistry, MYC gene amplification on molecular testing, and disease progression were consistent with the characteristics of GBM-PNC, the absence of corresponding morphological evidence led to a diagnosis of GBM NOS, World Health Organization grade IV. Postoperative examination demonstrated tumor metastases in the head, thoracic, and lumbosacral regions, suggesting ECM spread via CSF dissemination. In combination with the pathological findings, the case was ultimately considered a transitional or atypical GBM-PNC. INTERVENTIONS: After evaluating the patient's condition, the tumor was completely resected surgically. Postoperatively, the patient underwent radiotherapy, chemotherapy, and regular follow-up. Two months later, tumor metastases were detected. In addition to the original treatment regimen, intrathecal methotrexate injections were administered. OUTCOMES: Two months after surgery, tumor metastasis was detected. Treatment with radiotherapy, chemotherapy, and intrathecal drug injections effectively controlled disease progression. However, the patient's condition deteriorated 10 months postoperatively, and he ultimately passed away 14 months after the initial surgery. LESSONS: Based on this case and a review of relevant literature, it can be inferred that MYC amplification may serve as an early predictive biomarker for ECM via CSF dissemination in GBM. Furthermore, MYC gene overexpression may promote the transformation of primitive cells, and this case may represent a transitional or atypical GBM-PNC. This case suggests that clinicians should remain vigilant for the potential of CSF dissemination and ECM in GBM patients, particularly when MYC amplification is present, which could serve as an early warning of distant metastasis.