[A case of isolated mycobacterial focal meningitis diagnosed on brain and meningeal biopsy].

A 76-year-old woman was admitted to our hospital because of convulsions that developed after a 1-month history of progressive right-leg palsy. MRI showed thickening of the meninges with gadolinium enhancement in the left parietal lobe and it revealed pia-subarachnoid space pattern. A lumbar puncture was performed, and cerebrospinal fluid analysis revealed no abnormality. Her serum adenosine deaminase level was elevated (28.7 IU/l). The results of serum cultures were normal. To differentially diagnose collagen disease, infection, malignancy, and inflammation of uncommon causes, we conducted brain and meningeal biopsies on the 15th hospital day. Histopathological examination of the brain tissue showed mainly necrosis and inflammation. There was severe pachymeningeal thickening without necrosis. Although it was difficult to reach a definitive diagnosis, a tissue sample taken from under the leptomeninges tested positive for mycobacterium on Ziehl-Neelsen staining. The results of polymerase chain reaction for mycobacterium were negative in the meningeal tissue. The patient received anti-tuberculous drugs, anti-nontuberculous mycobacteriosis drugs, and corticosteroids to treat Mycobacterium tuberculosis and nontuberculous mycobacterium. After starting treatment, the findings on magnetic resonance imaging improved dramatically, and no convulsions occurred during hospitalization. She was discharged on the 153rd hospital day without any neurological deficit. Because previous studies have reported that isolated mycobacterium meningitis is a diagnostically challenging condition, brain and meningeal biopsies should be considered in patients with gadolinium enhancement in the meninges.