Adolescent massive delayed intratumoral hemorrhage in a long-standing pilocytic astrocytoma: A case report

Background: Pilocytic astrocytoma (PA) is a World Health Organization (WHO) Grade I glioma with generally indolent behavior. Spontaneous intratumoral hemorrhage is uncommon, and massive bleeding years after initial diagnosis is exceedingly rare. Case Description: A 16-year-old male with right thalamic PA underwent subtotal resection and ventriculoperitoneal shunt placement in 2018. Surveillance magnetic resonance imaging through May 2025 showed a stable residual tumor (~7 × 4 × 5 cm). In July 2025, he presented with an acute headache, vomiting, altered consciousness Glasgow coma scale 7 (GCS 7), and left hemiplegia. Computed tomography revealed a ~4.5 × 5 × 4.5 cm intratumoral hemorrhage with intraventricular extension and obstructive hydrocephalus. Emergent external ventricular drain placement, right frontal craniotomy, hematoma evacuation, and biopsy were performed. Histopathology confirmed WHO Grade I PA (Ki-67 <4%, p53 wild-type, isocitrate dehydrogenase 1 (IDH 1)-negative) with no evidence of malignant transformation. No systemic coagulopathy or trauma was identified. The patient improved neurologically and was discharged in stable condition. Conclusion: This case represents a rare delayed hemorrhage in a long-standing PA without malignant transformation. It highlights that even radiologically stable low-grade gliomas may carry a small risk of catastrophic bleeding and shows the importance of long-term follow-up and awareness of this potential complication.