Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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November 18, 2021
Giant Intracerebral Mature Tuberculoma
- Background:
- The most common parenchymal lesion in CNS tuberculosis is tuberculoma.
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Tuberculoma is a focal parenchymal infection with central caseating necrosis. Most tuberculomas are mature, solid, and caseating.
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Most are small (less than 2 cm). Giant tuberculomas can reach 6 cm.
- Clinical Presentation:
- Tuberculomas are more common in developing countries, particularly in children.
- Presentation varies from fever and headache to confusion, lethargy, seizures, and coma.
- Symptoms of increased intracranial pressure are common.
- Key Diagnostic Features:
- CNS tuberculosis has several distinct pathologic manifestations, including acute/subacute meningitis, tuberculomas, tuberculous abscess, and miliary brain tuberculosis.
- The imaging appearance is variable. Most tuberculomas occur in the cerebral hemispheres, especially the frontal and parietal lobes; isolated localized involvement along with the basal cisterns or in the Sylvian fissure unilaterally can also occur.
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MRI demonstrates lesions that appear hypo- or isointense on T1WI and hypointense on T2WI with occasional peripheral hypointensity on SWI (capsule rich in paramagnetic ions). A disproportionately large amount of vasogenic edema can point toward an infective process.
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Solid caseating tuberculomas do not restrict on DWI, although liquefied foci may restrict.
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Enhancement is variable, with lobulated ring enhancement around a nonenhancing center being the most typical. Tuberculomas may be associated with tuberculosis meningitis that appears like marked linear or nodular meningeal enhancement on T1 C+ with fat saturation.
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Magnetic resonance spectroscopy showing a decrease in NAA/Cr with a modest decrease in NAA/Cho and a large lipid peak with an absence of the other metabolites is typical.
- Differential Diagnoses:
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Pyogenic abscesses: Round or ovoid; T2 hyperintense with a peripheral hypointense ring on SWI; restrict on DWI; T1 C+ shows a ringlike enhancement; spectroscopy shows cytosolic amino acids, lactate, and acetate in the necrotic core.
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Primary or metastatic neoplasm: Especially a multifocal glioblastoma, which tends to be infiltrating, whereas metastases are almost always round and well demarcated; the presence of a peripheral hypointense ring on SWI favors the diagnosis of tuberculomas; the Cho/Cr ratio of tuberculomas is lower than that of malignant brain lesions.
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Giant colloidal vesicular neurocysticercosis: T2-hyperintense cyst with mild hyperintense signal on T1WI; scolex appears hyperintense on FLAIR; restricted diffusion can be seen in the scolex and viscous degenerating cyst; T1 C+ shows a ringlike enhancement.
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Tumefactive demyelination: Often has a restricted demyelinating front with an open ring pattern of enhancement on T1 C+ (horseshoe)
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Lymphoma: Solid lesions demonstrate ring enhancement and may be associated with leptomeningeal involvement; often restrict on DWI, with no peripheral hypointense ring on SWI; MR spectroscopy shows elevated choline and high lipid.
- Neurosarcoidosis: Enhancing mass lesions are usually associated with leptomeningeal disease spread along the perivascular spaces. Other sites of involvement are the hypothalamus and infundibulum.
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Treatment:
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Antitubercular therapy
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Surgery is considered on an emergent basis in the event of failure of medical therapy or progressively increasing size of tuberculoma.
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