Distal noncontiguous recurrence and sarcomatous transformation of glioblastoma with stable molecular profile: illustrative case

This case illustrates a rare pattern of GB progression, characterized by distal extra-axial recurrence with sarcomatoid transformation. The shared driver TERT, PIK3CA, and PTEN mutations in the original right temporal and subsequent left extra-axial lesion support clonal evolution, while the newly acquired TP53 alteration may underlie histological shift. Clinicians should consider histological transformation when evaluating atypical or extracranial recurrences, as molecular continuity with the primary tumor can guide interpretation of tumor biology and recurrence patterns. https://thejns.org/doi/10.3171/CASE25714.