Tuberculous brain abscess
A 65-year-old lady presented with headach for more than 3 months. Her symptoms began with projectile bouts of vomiting initially. An MRI scan was performed for further evaluation.
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The MRI shows a well defined thick walled cystic lesion in the left basal ganglia which has mild peripheral edema and associated with considerable mass effect, especially on the foramen of monro, which causes obliteration of the left frontal horn of the lateral ventricle. After the administration of contrast medium, the mass shows thick ring-like enhancement. You can see a small projection of the mass in the medial side of it, which seems to be trying to cross the midline and creates the butterfly fashion.
The presence of irregular wall thickening favors a malignant process, and lack of marked peripheral edema, also indicates a benign lesion. On the other hand, the location of this lesion, in the deep white matter, suggests the diagnosis of lymphoma. However, the patient underwent a craniotomy and the mass was resected. Histopathology revealed that no malignant cell was observed, and the diagnosis of malignancy was excluded, so the presence of brain abscess has been implicated and microbiology evaluation was performed. Although the abscess has generally a thin wall, in this case we can see the opposite. Unfortunately, the microbiological test performing a few hours prior to the patint's death reveled that the causative organism was Mycobacterium tuberculosis. Because extensive peripheral edema is a hallmark finding of metastasis, GBM or abscess differential diagnosis of intracerebral space occupying lesions with ring enhancement includes them.
Regarding this same patient, due to the partial treatment and use of corticosteroid, a thicker capsule and less amounts of edema were found, whilst the Granulomatous abscesses tend to make a thicker ring by its own.