On MRI, a brain tumor shows restricted diffusion on DWI (bright DWI, dark ADC), suggesting high cellularity. Ring enhancement with a central necrotic core, mass effect, and surrounding FLAIR hyperintensity are noted. Spectroscopy shows elevated choline, decreased NAA, and a lipid-lactate peak. Which diagnosis is MOST consistent?
- A Primary CNS lymphoma
- B Cerebral abscess
- C Tumefactive MS
- D Glioblastoma multiforme (GBM) ✓
Explanation
Glioblastoma multiforme classically shows thick irregular ring enhancement, central necrosis, surrounding FLAIR edema, and restricted diffusion in the cellular rim. MR spectroscopy demonstrates markedly elevated choline (membrane turnover), decreased NAA (neuronal loss), and lipid-lactate peaks (necrosis/anaerobic metabolism). This pattern distinguishes GBM from cerebral abscess, which shows restricted diffusion in the pus-filled center (not the rim), with amino-acid and acetate/succinate peaks on spectroscopy. CNS lymphoma shows solid homogeneous enhancement with restricted diffusion throughout the lesion. Tumefactive MS shows incomplete ring enhancement opening toward cortex.
Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.