Intracranial tuberculous granuloma

Clinical History

A 19-year-old female patient presented with headache, vomiting and low-grade fever for 1 month. She had a past history of pulmonary tuberculosis 2 years ago and was a treatment defaulter.

Imaging Findings

There are multiple discrete altered signal intensity lesions involving bilateral cerebral and cerebellar hemispheres. On T1W images, the lesions appear hypo-isointense (Fig. 1). On T2W images, these lesions appear hypointense with peripheral hyperintense rim (Fig. 2). There is mild to moderate perilesional oedema. The lesions do not show diffusion restriction (Fig. 4). The post-contrast study shows peripheral ring-like enhancement of the lesions (Fig. 5). Based on the above imaging findings and in view of the clinical profile and past history, the lesions are suggestive of intracranial tuberculomas.

Discussion

Intracranial tuberculomas are space-occupying masses of granulomatous tissue that result from haematogenous spread from a distant focus of tuberculous infection. Histologically, the mature tuberculomas are composed of a necrotic caseous centre surrounded by a capsule that contains fibroblasts, epithelioid cells, Langhans giant cells, and lymphocytes [1].

Intracranial tuberculomas can occur at any age. In developing countries young adults and children are predominantly affected while in developed countries they are more common in older patients. The symptoms produced by tuberculoma are related to their location. Low-grade fever, headache, vomiting, seizures, focal neurological deficit, and papilloedema are characteristic clinical features of supratentorial tuberculomas. Intratentorial tuberculomas are more common in children and may present with brainstem syndromes, cerebellar manifestations, and multiple cranial nerve palsies [2].

On CT, tuberculomas are characterised as low- or high-density and rounded or lobulated masses and show intense homogenous or ring enhancement after contrast administration. They have an irregular wall of varying thickness. Moderate to marked perilesional oedema is frequently present. On CT, the ‘target sign’, a central calcification or nidus surrounded by a ring that enhances after contrast administration, is considered pathognomonic of tuberculoma. The MRI features of tuberculoma depend on whether the lesion is non-caseating, caseating with a solid centre, or caseating with a liquid centre. The non-caseating granulomas are hypointense on T1-weighted images and hyperintense on T2-weighted images; after contrast administration the lesion usually shows homogenous enhancement. The second type of tuberculoma are hypointense or isointense on T1-weighted images and also on T2-weighted image. After contrast administration there is ring enhancement. These types of granuloma have a variable degree of perilesional oedema. The tuberculoma with central liquefaction of the caseous material appears centrally hypointense on T1- and hyperintense on T2-weighted images with a peripheral hypointense ring which represents the capsule of tuberculoma. Images after contrast administration show ring enhancement [2].

The WHO put CNS tuberculosis under TB treatment Category 1, and recommends initial phase therapy (for 2 months) with streptomycin, isoniazid, rifamipicin and pyrazinamide, followed by a 7-month continuation phase with isoniazid and rifampicin. However, a number of other studies report varying experiences with short-course (6 months) treatment. Intracranial tuberculomas that act as single space-occupying lesions with midline shifts and increased intracranial pressure, and that fail to respond to chemotherapy should be surgically removed. If the tuberculoma is totally removed, about 80% of patients will enjoy long-term recovery, particularly if they were treated in the early stage of the disease [2].

Differential Diagnosis List

Final Diagnosis

Intracranial tuberculous granuloma (Tuberculoma)

URL:	https://www.eurorad.org/case/13344
DOI:	10.1594/EURORAD/CASE.13344
ISSN:	1563-4086