A 45-year-old woman presents with progressive headache. MRI shows a T1 hypointense, T2 hyperintense ring-enhancing lesion in the white matter with surrounding oedema and an inner hypointense rim on T2* (susceptibility-weighted imaging). Spectroscopy shows elevated choline, decreased NAA, and a lipid/lactate peak. What is the most likely diagnosis?
- A Brain abscess
- B Tumefactive multiple sclerosis
- C High-grade glioma (GBM) ✓
- D Metastatic carcinoma
Explanation
Glioblastoma (WHO grade 4 glioma) classically presents as a ring-enhancing mass in the white matter with irregular thick enhancement, surrounding vasogenic oedema, and areas of necrosis. The T2* hypointense rim reflects haemosiderin from prior microhaemorrhages, a feature of GBM's neovascularization. MR spectroscopy shows elevated choline (cell membrane turnover), reduced NAA (neuronal loss), and a lipid/lactate peak (necrosis/anaerobic metabolism). Brain abscess shows restricted diffusion on DWI within the ring (pus) with smooth thin-walled enhancement. Metastases are often multifocal at grey-white junction. Tumefactive MS has an open ring enhancement pattern.
Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.
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Written and medically reviewed by the StethoPrep medical team.