[A case of brain tuberculoma resembling a malignant tumor]

A 35-year-old Sudanese man experienced bitter tastes on the right side of his tongue from January 2012. He was admitted to our hospital in March 2012 because of the appearance of distress, right facial palsy, nausea, and dizziness from late February 2012. A neurological examination revealed Bruns nystagmus, which increased on rightward gaze, as well as total hypoesthesia in the distribution of the maxillary branch of the right trigeminal nerve, moderate right peripheral type facial nerve palsy, and limb ataxia on the right side. Neither muscle weakness nor sensory disturbance was observed. Slight hyperreflexia was noted in the right extremities, and bilateral plantar responses were flexor. He showed wide-based ataxic gait and was unable to do tandem gait. Brain CT scans and magnetic resonance (MR) images revealed a mass lesion in the right pons to the right middle cerebellar peduncle with ring enhancement, suggestive of a "target" sign. Laboratory tests, including hematological and biochemical analyses, tumor markers, and antibodies, had normal values while the tuberculin reaction and QuantiFERON-TB Gold were strongly positive. Cerebrospinal fluid analysis revealed a slight increase in the protein level (76 mg/dl) with a normal cell count (2 per μl), and polymerase chain reaction-based tests and cultures were negative for Mycobacterium tuberculosis three times. Right subclavicular lymph node and right adrenal gland showed accumulation of fluorodeoxyglucose on positron emission tomography-CT, as did the mass lesion in the brainstem. These findings suggested a possibility of a metastatic malignant tumor or extrapleural tuberculoma. Because of the patient's religious belief, we were unable to perform a biopsy of the lymph node, and thus administered anti-tuberculous drugs. With treatment, his neurological symptoms such as facial palsy and ataxia improved steadily except for paradoxical worsening for the initial five days, and the gadolinium-enhanced lesion shrunk markedly. Follow-up MR images demonstrated that the lesions did not expand further for 9 months. From this course of treatment, we diagnosed the patient's tumor as brainstem tuberculoma. Brain tuberculoma sometimes resembles a malignant tumor, and it is therefore challenging to diagnose brainstem tuberculosis in cases without lung lesions. It is important to make a comprehensive diagnosis based on the patient's background, imaging, and course of treatment, and to treat brainstem tuberculoma promptly.