22 CASE REPORT: GLIOBLASTOMA OCCURRING 40 YEARS AFTER TREATMENT FOR MEDULLOBLASTOMA IN THE POSTERIOR FOSSA

Abstract

We present the case of a 44-year-old male who developed a radiation-induced glioblastoma (RIG) at the same site as a medulloblastoma treated in early childhood. The patient initially underwent suboccipital craniotomy and craniospinal radiotherapy at age four. Four decades later, he presented with new-onset ataxia, concentration difficulties, and occipital headache. MRI revealed a 3.8 cm enhancing lesion in the right cerebellar hemisphere. Surgical debulking was performed, and histology confirmed a paediatric-type high-grade glioma, RTK1 subtype, MGMT-unmethylated. This case meets all modified Cahan’s criteria for a radiation-induced malignancy, representing the longest reported latency period (40 years) between medulloblastoma treatment and RIG onset. Radiation-induced gliomas are rare but recognised complications of therapeutic cranial irradiation, with high-dose exposure in early childhood conferring significant long-term risk. While spontaneous glioblastomas in the cerebellum are uncommon in adults, RIGs more frequently occur in atypical locations such as the posterior fossa. This case underscores the necessity of long-term vigilance in survivors of paediatric brain tumours and contributes to the limited literature on very-late-onset RIGs.