A 45-year-old man presents with progressive headaches and seizures. MRI shows a 3 cm ring-enhancing lesion in the left temporal lobe with surrounding edema and mass effect. The radiological finding that most strongly suggests glioblastoma multiforme (GBM) rather than a brain metastasis is:

• A Location at the grey-white matter junction
• B Presence of edema around the lesion
• C Irregular thick ring enhancement with central necrosis and 'butterfly' extension across the corpus callosum ✓
• D Single lesion on MRI

Explanation

GBM (WHO Grade IV astrocytoma) characteristically shows irregular, thick ring enhancement with central necrosis (reflecting tumor heterogeneity), surrounding vasogenic edema, and may extend across the corpus callosum producing a 'butterfly glioma' pattern — virtually pathognomonic for GBM. Metastases typically appear at the grey-white matter junction (high blood-flow interface), are often multiple, and have thin regular ring enhancement with a clear margin. A single lesion can be either; bilateral corpus callosum involvement strongly favors GBM.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.