胃切除後の低ガンマグロブリン血症に生じた黒色真菌Cladophialophora bantianaによる脳膿瘍の1例

Brain Abscess due to Infection with Dematiaceous Fungi Cladophialophora bantiana Associated with Hypogammaglobulinemia Following Gastrectomy:A Case Report

Ⅰ．はじめに

　黒色真菌は細胞壁内にメラニン様色素を有するために黒色調を呈する真菌の総称で，これまでに，Fonsecaea pedrosoi，Exophiala jeanselmei，E. dermatitidis，Phialophora verrucosa，Cladophialophora bantianaなどの24種が報告されている^7-9,11)．さまざまな部位に感染して黒色真菌症（phaeohyphomycosis）を引き起こすが，そのほとんどは皮膚への感染である⁵⁾．本邦における報告でも，土壌，木，腐食食物に生息する黒色真菌が，外表皮膚に受けた軽微な外傷から進入することで，皮膚感染症を引き起こすことがほとんどである^5,7-9)．稀に中枢神経系への感染を起こすこと（cerebral phaeohyphomycosis）があるが，その多くは重篤な免疫不全状態に生じており，予後は極めて不良であるとされている^4,7-9)．われわれは20年前に受けた胃亜全摘出術で生じたと考えられる低ガンマグロブリン血症に関連して，黒色真菌による脳膿瘍を生じた稀な1例を経験したので，報告する．

　Dematiaceous fungi have melanin-like pigment in the cell wall and usually cause a variety of dermal infections in humans. Infections of the central nervous system（cerebral phaeohyphomycosis）are rare but serious, since they commonly occur in immunocompromized patients. A 76-year-old man was admitted with mild motor aphasia and underwent total excision of a mass in the left frontal lobe. With the postoperative diagnosis of brain abscess due to infection with dematiaceous fungi（C. bantiana）associated with hypogammaglobulinemia following gastrectomy, intravenous antifungal drugs including amphotericin B and fluconazole were administered. Regrowth of the abscess with intraventricular rupture was noted at about the 88th day after the initial surgery, and the patient underwent neuroendoscopic aspiration of the pus and placement of a ventricular drain. Following intraventricular administration of miconazole through ventricular drainage or an Ommaya reservoir, neuroradiological findings improved, but general and neurological conditions worsened. Further treatment was discontinued and the patient died 9 months after onset. The poor outcome in this patient is attributed to 1）intractability of dematiaceous fungi, 2）development of ventriculitis and the need for intraventricular administration of antifungal drugs, and 3）untreatable hypogammaglobulinemia following gastrectomy.