頭蓋内結核腫が疑われた症例のMRI経過

Serial MRI Findings of Intracranial Tuberculomas : A Case Report and Review of the Literature

頭蓋内結核腫は先進国において比較的まれな疾患であり，臨床の場で遭遇する頻度は必ずしも高くはない。症例は74歳女性。類天疱瘡に対しするステロイド療法中，進行性の歩行障害を主訴に当科に入院した。脳脊髄液検査で好中球優位の細胞数増多と糖の軽度低下を認め，頭部造影MRI所見で，リング状に造影される多発性の病巣がみられた。脳膿瘍が疑われたが，抗生剤治療に反応なく，さらに意識障害，右片麻痺などの神経症状の出現を認め，MRI所見も増悪した。一方，胸部CTで左肺に空洞性陰影を認め，頭蓋内多発病巣が拡散強調画像で均一な高信号を呈していたことから，頭蓋内結核腫の可能性を考えた。抗結核剤の投与を開始し，治療開始1カ月後から徐々に神経症状は改善し，頭部MRIで認めた多発性病巣は縮小した。本例は他の検査で診断し得なかった頭蓋内結核腫の診断を行う上で拡散強調画像が有用であったと考えられる。

Intracranial tuberculoma is an infectious disorder, occurring with or without tuberculous meningitis. Although intracranial tuberculoma is rare in developed countries, its frequency has increased in recent years in association with aging and immunocompromised hosts. Because of the low sensitivity of Mycobacterium tuberculosis cultures or of DNA detection from cerebrospinal fluid, diagnosis of intracranial tuberculoma is often difficult. Conventional magnetic resonance （MR） imaging of the tuberculoma yields variable results and is indistinct from other inflammatory lesions or brain tumors. We report the case of a 74-year-old woman with progressive neurologic deterioration. MR imaging of the brain showed multiple ring-like enhancing lesions in the supra- and infra-tentorial regions, mimicking multiple metastatic brain tumors. Diffusion-weighted imaging （DWI） of the brain showed homogeneous high signals in each lesion. A cavity in the lung suggested systemic involvement of tuberculosis. Despite extensive examination, tuberculosis could not be detected. Nevertheless, anti-tuberculosis treatment was administered. The patient's neurologic condition initially deteriorated for 4 weeks, then gradually improved. MRI showed marked improvement of the lesions after anti-tuberculosis treatment. Whereas conventional MRI is not specific in such cases, DWI might be useful for early assessment of intracranial tuberculosis.