Brain abscess with dual rim sign

Case contributed by Dr Luu Hanh

Presentation

Sudden weakness on the right side of the body, fever.

Patient Data

Age: 85 years
Gender: Male

The lesions demonstrate central restricted diffusion on DWI, ring enhancement on T1 C+, dual rim sign on Flair/T2 involving left parietal-occipital lobe and left temporal lobe in keeping with brain abscess

There are peritumoral vasogenic edema and mass effect to compress adjacent brain parenchyma and left lateral ventricle.

Annotated image

Dual rim sign: the green arrow indicates the hyperintense inner rim, the red arrow indicates the hypointense outer rim overlapping the contrast-enhancing rim.

Case Discussion

Dual rim sign is seen on T2/Flair/SWI, including two concentric rims surrounding the abscess cavity, the outer one is hypointense, and the inner one is hyperintense. 

Dual rim sign helps distinguish an abscess from a glioblastoma. The hypointense rim typically demonstrates a thin, complete, regular overlapping the contrast-enhancing rim in cerebral abscesses. In glioblastoma, the T2 hypointense line is inner to the contrast-enhancing rim and is irregular, incomplete. 

On histopathology, the outer rim corresponds to the capsule abscess in which the production of paramagnetic free radicals by macrophages resulting in magnetic susceptibility 1. The granulation tissues between the necrotic center and capsule are responsible for the hyperintense inner rim 1,2.
In contrast, the random deposition of hemorrhagic products at the edge of the necrotic cavity glioblastoma causes the irregular, incomplete, hypointense margin on SWI 1,2.

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Case information

rID: 87566
Published: 10th Mar 2021
Last edited: 12th Mar 2021
Inclusion in quiz mode: Included
Institution: Ninh Binh general hospital

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