Please give your comments on these MRI images. Please submit your answers in the comments section only for consideration, give the findings and possible diagnosis or D/D. List of people who give correct answers within 3days will be featured in this blog along with the correct answer which will be posted on 17th January.
Answer: Tumefactive demyelination with open rim enhancement.
Explanation: The open-ring or white-matter-crescent sign. This sign may help distinguish ring enhancing lesions caused by demyelination from more frequent causes, like neoplasms or abscesses. Note that the ring enhancement in the demyelinating lesion is open in areas abuting the cortex or other gray matter areas, such as the amigdala. The enhancement corresponds to the areas of most active demyelinating activity, with marked breakdown of the blood brain barrier. Once demyelination is complete, in the center of the lesion, enhancement abates. The cortex does not enhance.
The open ring sign is a relatively specific sign for demyelination, helpful in distinguishing between ring enhancing lesions. The enhancing component is thought to represent advancing front of demyelination and thus favours the white matter side of the lesion. The open part of the ring will therefore usually point towards the grey matter
Often patients with such lesions undergo biopsy, where the histology can be difficult to interpret. Abundant bizarre astrocytes with frequent mitoses can suggest the diagnosis of GBM. Toxoplasmosis may also be suggested by the presence of giant cells (Creutzfeldt cells). As such, careful assessment of imaging is essential to avoid unnecessary and misleading intervention.
Further reading: Open-ring imaging sign: highly specific for atypical brain demyelination.
Masdeu JC, Quinto C, Olivera C, Tenner M, Leslie D, Visintainer P. Source. Departments of Neurology, New York Medical College (St. Vincent's Hospital and Westchester Medical Center), Valhalla, NY , USA. firstname.lastname@example.org
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