A case of multiple intracranial tuberculoma diagnosed by open brain biopsy

To provide histological diagnoses of brain diseases, CT-guided stereotactic brain biopsy (CT-SBB) has been widely used because of its less invasive technique compared with open brain biopsy (OBB). However, CT-SBB is not always diagnostic. We report a case of multiple intracranial tuberculoma whose diagnosis was not made by CT-SBB but by OBB. The patient is a 46-year- old man with insulin-dependent diabetes mellitus who had been receiving immunosuppressive agents (azathioprine, ciclosporin, and prednisolone) after renal transplantation for diabetic renal failure for 9 years. He gradually developed febrile, headache and unsteady gait. Brain MRI demonstrated multiple intracranial lesions involving left fronto-temporal and right parietal lobes, left cerebellar hemisphere, and the fourth ventricle. Although the MRI findings were consistent with those of previously reported cases of intracranial tuberculoma, other conditions, such as malignant lymphoma and toxoplasmosis, were not ruled out. Therefore, CT-SBB targeting the left temporal lobe lesion was done for definitive diagnosis, but it revealed only mild perivascular infiltration of mononuclear cells and hemorrhage. He was transferred to our clinic for further evaluation. On examination, mild truncal and limb ataxia on the left were noted in addition to the neurological findings corresponding to diabetic retinopathy and neuropathy. Despite vigorous laboratory examinations, including repeated bacterial cultures and PCR of cerebrospinal fluid, no evidence of tuberculous infection was obtained. A tentative diagnosis of multiple intracranial tuberculoma was made, and anti-tuberculous drugs (isoniazid 400mg, ethambutol 750mg, and pyrazinamide 1.5g) were administered. Since his symptoms deteriorated because of ventricular dilatation resulting from the enlarged lesion in the fourth ventricle after a temporary clinical improvement, VP- shunting and OBB from the left temporal lobe lesion were done. The excised lesion was firmly encapsulated and the histological examination revealed typical pathology of tuberculoma. Ziehl-Neelsen staining and PCR for Mycobacterium tuberculosis of the biopsied specimen were also positive. Further administration of increased doses of anti-tuberculous drugs (isoniazid 600mg, ethambutol 500mg, pyrazinamide 2.0g and intramuscular injection of streptomycin 0.3g twice a week) eventually ameliorated the symptoms and shrank the lesions. In case of intracranial tuberculoma, the needle of CT-SBB may not penetrate the firm capsule of tuberculoma and only the surrounding brain tissue may be obtained as in the present case. Therefore, it is recommended to consider OBB from the beginning for definitive diagnosis of intracranial tuberculoma. Paradoxical worsening of the clinical and laboratory findings of tuberculosis in spite of appropriate antituberculous therapy as seen in the present case has been described in both pulmonary and extra-pulmonary tuberculosis. The phenomenon, called transient worsening, could happen and we have to keep it in mind during the treatment of intracerebral tuberculoma.