MRI brain of a 28-year-old woman shows multiple periventricular white matter T2/FLAIR hyperintensities perpendicular to the corpus callosum (Dawson fingers), with one open-ring enhancing lesion. CSF shows oligoclonal bands. The diagnosis and prognostically relevant lesion feature are:
- A ADEM — open-ring enhancement indicates perivenular inflammation
- B CNS lymphoma — ring enhancement with central necrosis
- C Multiple sclerosis — open-ring enhancement (incomplete ring facing white matter) is characteristic of demyelinating lesion ✓
- D Neuromyelitis optica — lesions extend into corpus callosum
Correct answer: C. Multiple sclerosis — open-ring enhancement (incomplete ring facing white matter) is characteristic of demyelinating lesion
Explanation
Multiple sclerosis (MS) classically shows ovoid periventricular lesions oriented perpendicular to the corpus callosum (Dawson fingers on sagittal FLAIR), and enhancing active lesions. The open-ring enhancement pattern (incomplete ring with the open side facing the grey matter/cortex) is highly specific for demyelinating lesions and helps distinguish MS from abscess or metastasis (which show complete ring). CSF oligoclonal bands confirm intrathecal inflammation.
Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.