Presentation
Worsening memory and confusion. Incontinence.
Patient Data
There is a lobulated, vividly enhancing mass within the right temporal lobe. The mass demonstrates heterogeneous T1 and T2 signal and multiple round/ovoid foci of internal non-enhancement, these foci demonstrating central elevated signal on diffusion-weighted imaging with ADC depression. More superiorly, an ovoid low T1, high T2 focus measuring 32 x 18 mm demonstrates no DWI signal elevation.
There is very extensive right frontotemporoparietal T2/FLAIR hyperintensity in keeping with surrounding vasogenic edema, infiltrating the basal ganglia, effacing right cerebral sulci, narrowing the right lateral ventricle and resulting in marked contralateral (left) lateral ventricular distension (trapped ventricle). There is uncal herniation on the right, moderate leftward subfalcine herniation and leftward midline shift. Some periventricular T2/FLAIR hyperintensity likely reflects some transependymal edema.
The inferior aspect of the mass abuts the right Sylvian fissure, abutting and narrowing the right middle cerebral artery as well as displacing it anteriorly with probable encasement of several branches. The dura adjacent to the mass at the temporal pole appears thickened and enhances. No extra-axial collection is seen.
There is elevated CBV in the enhancing portion of the mass. MRS is non-contributory (not shown). Gradient sequences demonstrate no focal intracerebral hemorrhage.
No other abnormal focus of contrast enhancement is identified.
Conclusion:
Large right temporal lobe mass with vivid enhancement. Internal foci of non-enhancement with central DWI signal elevation/ADC depression in a component raises the possibility for a multiloculated cerebral abscess (especially from an atypical organism, e.g. TB) although the restricting component could represent protein-rich necrotic fluid in a high-grade glioma.
Case Discussion
The patient went on to have a resection confirming suggesting that this represents a tuberculoma.
Histology
Sections of the brain parenchyma show necrotizing granulomatous inflammation. There are nodular aggregates of epithelioid histiocytes with multinucleated giant cells, forming granulomas with central areas of necrosis. There are abundant surrounding lymphocytes and plasma cells, some neutrophils and fibrosis. No evidence of malignancy is identified. The Grocott stain shows no fungi. The Ziehl-Neelsen stain shows no acid-fast bacilli.
Serology
- Strongyloides IgG by EIA: 0.01 Negative
- Cysticercosis IgG Antibody by EIA: 0.04 Not detected
- HIV Negative
Microbiology
- GRAM STAIN
- Leukocytes not detected
- No organisms seen
- CULTURE: No Growth
- ACTINOMYCES CULTURE: No growth after 14 days.
- MYCOBACTERIUM CULTURE SCREEN MGIT bottle 56 days: Negative
- NUCLEIC ACID TESTING (ON SPECIMEN)
- DNA amplification assay for M.tuberculosis: NOT Detected
- COMMENT: A negative result may not exclude the presence of M.tuberculosis
Discussion
Although TB PCR was negative, as were the cultures, the overall favored diagnosis based on histology is of a tuberculoma, as isolating TB is notoriously difficult. The patient was commenced on anti-mycobacterial medication and has gradually improved.
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